research article an efficient full-wave...

Research ArticleAn Efficient Full-Wave Electromagnetic Analysis forCapacitive Body-Coupled Communication

Muhammad Irfan Kazim1 Muhammad Imran Kazim2 and J Jacob Wikner1

1Department of Electrical Engineering Linkoping University 581 83 Linkoping Sweden2Department of Electrical Engineering Eindhoven University of Technology (TUe) PO Box 513 5600 MB Eindhoven Netherlands

Correspondence should be addressed to Muhammad Irfan Kazim irfankazimisyliuse

Received 16 February 2015 Revised 28 April 2015 Accepted 4 May 2015

Academic Editor Lorenzo Crocco

Copyright copy 2015 Muhammad Irfan Kazim et al This is an open access article distributed under the Creative CommonsAttribution License which permits unrestricted use distribution and reproduction in any medium provided the original work isproperly cited

Measured propagation loss for capacitive body-coupled communication (BCC) channel (1MHz to 60MHz) is limitedly availablein the literature for distances longer than 50 cm This is either because of experimental complexity to isolate the earth-ground ordesign complexity in realizing a reliable communication link to assess the performance limitations of capacitive BCC channelTherefore an alternate efficient full-wave electromagnetic (EM) simulation approach is presented to realistically analyze capacitiveBCC that is the interaction of capacitive coupler the human body and the environment all together The presented simulationapproach is first evaluated for numericalhuman body variation uncertainties and then validated with measurement results fromliterature followed by the analysis of capacitive BCC channel for twenty different scenarios The simulation results show thatthe vertical coupler configuration is less susceptible to physiological variations of underlying tissues compared to the horizontalcoupler configurationThe propagation loss is less for arm positions when they are not touching the torso region irrespective of thecommunication distanceThe propagation loss has also been explained for complex scenarios formed by the ground-plane and thematerial structures (metals or dielectrics) with the human body The estimated propagation loss has been used to investigate thelink-budget requirement for designing capacitive BCC system in CMOS sub-micron technologies

1 Introduction

Capacitive body-coupled communication (BCC) is consid-ered an enabling short-range wireless technology for theinteraction between humans and the smarter ambiance Theuseful frequency range falls between hundreds of kHz to tensof MHz [1] The capacitive BCC has an advantage over otherwireless technologies like Bluetooth and Zig-bee in the con-text of personal area network (PAN) and internet-of-things(IOT) due to lower power consumption and confinementof radiated energy thus requiring less allocation of specialfrequency bands for communication However the potentialof capacitive BCC for the aforesaid applications could befully utilized by understanding the realistic interaction ofthe capacitive coupler the human body (electrophysiologicalproperties of tissues) and the environment for differentscenarios and communication distances Although differentchip solutions have been presented for capacitive BCC [2

3] it is not clearly known for how many body positionsand for which coupler configurationsizes communicationdistances environment and so forth the results have beenreported A limited literature about experimental measure-ments for the propagation characteristics of capacitive BCCchannel is available the limitation being the experimentalsetup especially for distances longer than 50 cm A numberof factors which influence BCC include large variations inthe propagation characteristics with different body positionscoupler types and sizes types of indoor flooring furnitureand electronic equipment around us The other factorsencompass the difficulties in isolating the earth-groundedinstruments during body measurements and design com-plexity involved in implementing reliable battery-operatedhigh data-rate transceivers in the mid-frequency range of1MHz to 60MHz for bit-error-rate (BER) measurements

An alternate approach is to rely on circuit based models[4 5] or analytical [6] or numerical methods [7ndash11] to model

Hindawi Publishing CorporationInternational Journal of Antennas and PropagationVolume 2015 Article ID 245621 15 pageshttpdxdoiorg1011552015245621

2 International Journal of Antennas and Propagation

and analyze the capacitive BCC channel This paper pro-poses a systematic efficient full-wave electromagnetic (EM)approach to analyze capacitive BCC channel propagationloss characteristics and the influence of the aforesaid factorsThe analysis after validation with the measurement resultsconsiders the combined interaction of the capacitive couplerof different types and sizes the human body (electrophysio-logical properties of tissues) and the environment to explainpropagation loss for complex scenarios Moreover differentbody positions have also been analyzed over the usefulfrequency range of 1MHz to 60MHz for communicationdistances longer than 50 cm

This paper is divided into five sections Section 2 presentsan overview and comparison of the literature about themodeling of capacitive BCC channel Section 3 describesthe proposed efficient full-wave EM approach for analyzingcapacitive BCC The evaluation for numericalhuman bodyvariation uncertainties and validation with the measurementresults from the literature of the proposed approach is alsopresented in this section The effects of coupler configura-tions human body and the environment are estimated fromthe propagation loss curves and the electric field intensityplots which defines the scope of Section 4 The investigationof link-budget requirement based on the estimated propaga-tion loss is also carried out in this section followed by theconcluding remarks in Section 5

2 Literature Review Modeling of CapacitiveBCC Channel

Different propagation models for capacitive BCC channelhave been proposed in the literature with confined applicablescope Zimmerman [4] who pioneered this field presentedan electrical model which is based on electrostatic cou-pling between transmitter (Tx) and receiver (Rx) capac-itive electrodes and their capacitive return path throughexternal ground considering the human body as a perfectelectric conductor (PEC) with zero impedance This lumpedcapacitive model has been extended to a distributed parallelRC equivalent circuit model [5] The values of resistance(119877) and capacitance (119862) in this model have been derivedfrom the equivalent homogeneous human phantom modelof muscle for arm-torso-arm region considering conductioncurrent and voltage drop inside human body The limitationwith Zimmerman model [4] is that it perhaps takes intoaccount one particular scenario for empirically calculatingthe body and electrode capacitance from measured pathimpedance (possibly some typical values were also usedin the model whose adapted strategy for estimation is notclearly known) Similarly distributed RC parallel circuitvalues in [5] have been empirically calculated from theconsidered homogeneous phantom model (120590 = 02 Sm amp120598119903= 70) for one particular scenario Moreover the earth-

grounded instruments used in [5] also raises questions on theapplicability of these derived circuit parameters for practicalscenariosThe lumped coupling capacitance values suggestedin the Zimmerman model were estimated numerically in[7ndash9] Reference [7] proposed a four-terminal equivalent

circuit model with six impedances for two- and four-electrode arrangements The capacitance was determinednumerically under the electrostatic assumption using finiteelement method (FEM) The transmission gain calculatedby this circuit model was compared with the measuredresults at 1 kHz 10 kHz 100 kHz and 1000 kHz but theinstruments used in the measurement were not battery-operated but rather earth-grounded thereby indirectly shar-ing the common ground Another equivalent circuit modelpresented in [8] numerically calculated the mutual capac-itance for different scenarios by the method-of-moments(MoM) which were also verified by finite-difference time-domain (FDTD) method The different scenarios includeno-conductor grounded body grounded and transmitteror receiver grounded under quasi-electrostatic assumptionconsidering human body as a perfect electrically conductingsphere with negligible induced currents This model wasrefined in [9] by proposing an equivalent circuit model basedon lossy conductors inducing conduction currents inside thehuman arm phantomThe capacitance values were estimatedby the numerical analysis technique of MoM and verifiedby FDTD The relative permittivity and conductivity of thehuman armphantomused in [9] correspond to that of humanmuscle tissue onlyThe capacitance due to the outermost skinand fat dielectric layers have not been taken into consider-ation (while evaluating the equivalent lumped capacitance)The conductivity of muscle tissue is higher than outermostskin and fat tissues which undermines the proposed modelReference [6] has considered the surface of human body as aninfinite half-planewith skin-only tissue properties for verticalelectric-dipole type coupler The analytical model [6] usesthe derivation in [12 13] for defining the vertical componentof the electric field intensity due to the vertical dipole Theelectric field intensity expression after simplification includesthe surfacewave far-field propagationwith attenuation factorreactive inductive field radiation and quasi-static near-fieldtermsThis model takes into account the electrophysiologicalproperties in terms of relative permittivity and conductiv-ity of the human skin which is explicitly included in theexpression of surface wave attenuation factor But on theother hand this model generalizes the finite-sized verticalcoupler configuration with a theoretical infinitesimal dipolewhich results in deviation between theoretical and measuredresults and ismore pronouncedwhen the coupler dimensionsand communication distances are comparable Reference[10] considered the electrophysiological properties of skinand underneath living tissues in 3D finite element modelof human upper arm under quasi-electrostatic conditionsto study the attenuation characteristics but their study waslimited to 1MHzThe dielectric values used in this simulationmodel from [14] have larger uncertainties than average forfrequencies below 1MHz Moreover the effects of externalenvironment and earth-ground on the signal or propagationloss have also not been presented Reference [11] consideredthe combined effect of coupler muscle equivalent humanbody model and environment (earth-ground and materialstructures) at 10MHz but the simulation results are limitedto fixed size coupler fixed distance (19 cm) between couplersand same body position

International Journal of Antennas and Propagation 3

Metal

Metal

Airdielectric

1 cm

4 cm

4 cm

(a) Vertical coupler [4 times 4 times 1] with airdielectric

85 cm

55 cm

15 cm

25 cm

(b) Coplanar horizontal coupler [85 times 55 times1525]

Tx coupler Rx coupler

(c) Coplanar horizontal coupler (Longitudinal orientation)


(d) Coplanar horizontal coupler (Transversal orienta-tion)

Figure 1 Coupler configurations and their orientations

A summary of the reviewed literature concerning themodeling of capacitive BCC channel is summarized in Table 1with pros and cons The figures-of-merit for the comparisonare based on the realistic modeling of the interaction of thevariable coupler sizestypes the human tissues physiologicalproperties and the environment all together for differentbody positions over the useful frequency range of 1MHz to60MHz communication distances longer than 50 cm provi-sion of propagation model cosimulation in circuit simulatorand computational efficiency As can be seen from Table 1the approaches presented in the reviewed literature havelimitations in analyzing the interrelated effects of differentparameters The challenge is to model the problem as closeto the real setup as possible without making it computa-tively too intensive to handle The presented approach inthis paper is based on efficient full-wave EM solution torealistically model and understand the capacitive BCC withthe provision of creating different scenarios over the usefulfrequencycommunication distance range Although full-wave EM solution is computatively intensive in comparisonto the equivalent circuit model and analytical approaches thepresented approach reduces the complexity of the problemwith the simplified assumptions while quantifying the toler-ance bounds

3 Efficient Full-Wave EM Approach

An efficient full-wave EM approach for realistic modeling ofcapacitive BCC channel is presented in this section For thecapacitive BCC modeling the interaction of the coupler thewhole human body (considering electrophysiological proper-ties of tissues) and the environment all together is of impor-tance The modeling of the human body is very complex

and is the main contributing factor towards increasing thecomputational cost of any analysis The presented approachcarries out the modeling of human body by analyzing theeffects of stratification and curvature A single tissue layer ofthewhole humanmodelwith quantifiable tolerance bounds isconsidered afterwards for analysis tomake the approach com-putatively efficient The full-wave EM approach makes use ofthe 3D EM tool of Computer Simulation Technology (CST)Microwave Studio (MWS) for modeling of the capacitiveBCC channel CST is a 3D electromagnetic simulator basedon Finite Integration Technique (FIT) [18] which ldquoprovidesdiscrete reformulation of Maxwellrsquos equations in their integralformrdquo [19] The Maxwell equations are numerically solvedover the finite calculation domain enclosing the consideredproblem A suitable mesh splits this domain into many smallgrid cells for which the equations are solved separately

The following section first highlights the coupler configu-rations and the environment followed by the efficient humanbodymodeling by incorporating simplified assumptionsTheabove is discussed both in general and in context withCST MWS software The efficient full-wave EM approach isevaluated for numericalhuman body variation uncertaintiesand validated afterwards with the measurement results of theliterature

31 Coupler Configurations and Environment The front-end of the transmitter or receiver for capacitive BCCchannel consists of an electrode coupler structure whichis capacitive in nature The configurations of the coupler(verticalhorizontal) with different orientations (longitudi-naltransversal) are shown in Figure 1 The normally usedvertical couplers comprise two metal layers with air ordielectric material in between The two metal structures in


Table1Summaryandcomparis

onof

ther

eviewed

literaturec

oncerningthem

odelingof

capacitiv

eBCC

channel

Literature

review

[reference]

BCCprop

agation

mod

el

Coverageo

fmod

elingaspects

Mod

elcoverin

gdifferent

scenarios

Cosim

ulation

mod

elcirc

uit

provision

Com

putatio

nal

efficiency

Cou

pler

sizesty

pes

Body

tissues

physiology

Environm

ent

Body

positions

Frequency(1to

60MHz)

TxRxdistance

ge50

cm

[45]

Equivalent

circuit

Fixedsiz

e[4]

no[5]n

oNo[4]

phantom

[5]

No

No

No[4]10

to60

MHz[5]

No[4]yes[5]

Yes

Yes

[7ndash9

]RC

estim

ate

MOMFDTD

Noyes[7]no

Nomuscle

equivalent

[9]

No

No

No

No

Yes

Partial

[6]

Analytic

al(curve-fitting)

Infin

itesim

aldipo

leno

Skin-only

No

No

Yes

Yes

No

Yes

[10]

FEM

quasi-e

lectrosta

ticFixedsiz

eno

Skin-only

No

Yes

No

No

Not

mentio

ned

Partial

[11]

FDTD

Fixedsiz

eno

Muscle

equivalent

Yes

No

No

No

Not

mentio

ned

Partial

Thiswork

Efficientfull-w

ave

EMVa

riables

izeyes

Stratifi

edamp

skin-only

Yes

Yes

Yes

Yes

Yes(119878-m

atrix

)Partiallowast

lowast

Full-waveE

Misan

umericaltechniqu

ecompu

tativ

elyintensiveho

weveranapproach

ofmakingiteffi

cientyetaccurateispresented


horizontal configuration are separated by some distance onthe same side of the substrate The horizontal and verticalcoupler dimensions are expressed in this paper as [length timesbreadth times horizontalvertical spacing] described in Figure 1

External objects (aluminiumwood table steel cupboard)and different types of flooring (earth-ground) need to beconsidered for capacitive BCC channel modeling In CSTMWS the external objects can be modeled using differentconductive and dielectric materials whereas the electricboundary condition can be used to simulate the earth-groundflooring

32 Human Body Modeling The human body comprises anumber of layers each having its own dielectric propertieswhich are frequency dependentThe dispersion properties interms of complex permittivity (1205981015840 [real] and 12059810158401015840 [imaginary])for the four considered layers are determined from theeffective conductivity (120590

119890) and the relative permittivity (120598

119903)

values [15] and the use of the following relationships

1205981015840

= 1205980120598119903

12059810158401015840

= 1205981015840 tan 120575

tan 120575 =120590119890

21205871198911205981015840

(1)

where tan120575 is the loss-tangent of the dielectric and 119891 is thefrequency In CST MWS the dispersion properties of eachlayer can be specified by using the dispersion list in thematerial properties The dispersion list takes the normalizedvalues of 1205981015840 and 12059810158401015840 with respect to the free-space permittivity1205980 The normalized values of complex permittivity (1205981015840 [real]and 12059810158401015840 [imaginary]) of dry skin fat muscle and bonecortical from 1MHz to 60MHz which has been used infour-layer-stratified and skin-only models in CST MWShave been plotted in Figure 2 These values are based onthe parametric model of four Cole-Cole type dispersion andparameter values presented in [14 15] This model is reliablefor frequencies above 1MHz [14] which is also the reasonfor selecting 1MHz as the lower frequency for capacitiveBCC channel in this work The human arm models havebeen considered first to study the effect of stratificationand curvature Figure 3(a) represents the standard four-layer-stratified (Str4)model of a human arm [20] used in this workstarting from the outermost layer of skin to the innermostbone medium

33 Simulation Setup The transient solver of CST MWShas been used to study the effect of the stratification andcurvature of human model (Figures 3(a)ndash3(d)) on the BCCThe transient solver allows simulation of the model behaviorover a wide frequency range in a single computation runresulting in efficient computation for problems with openboundaries and large dimensions The accuracy of the fieldsolution increases with a finer mesh at the cost of increasedcomputation time Therefore both the global and local meshrefinement techniques have been used The open boundaryconditions have been defined to study the variation in

5 10 15 20 25 30 35 40 45 50 55

5 10 15 20 25 30 35 40 45 50 55Frequency (MHz)

104

103

102

101

104

103

102

101

Nor

mal

ized

(120598998400 )

Nor

mal

ized

(120598998400998400

)

120598998400 dry skin120598998400 wet skin120598998400 fat

120598998400 muscle120598998400 bone cortical120598998400 bone marrow



Figure 2 Normalized complex permittivity that is normalized 1205981015840(real) and normalized 12059810158401015840 (imaginary) values of dry skin fat muscleand bone cortical from 1MHz to 60MHz [15] used in four-layer-stratified model in CST MWS

propagation losses for the three cases (skin-only-cylinder(Sk-Cyl) skin-only-rectangle (Sk-Rec) and standard four-layer-stratified (Str4)) with variation of distance (119889) to 20 cm40 cm and 90 cm for a pair of two different coupler structures(vertical [6 times 6 times 3] and horizontal [5 times 2 times 1]) on transmitterand receiver sides For the excitation of the coupler CST hasthe provision of using either the wave guide or the discreteportThe selection of the specific port depends on the ease-of-use for problem under investigation For the inhomogeneousmodel like four-layer human arm model the discrete portis the preferred choice to avoid instability issues faced withwave guide portThediscrete ports of 50 ohmshave been usedto compare the arm models shown in Figures 3(b) 3(c) and3(d) to observe the relative variation of the propagation lossfor the three casesThe four-layer-stratifiedmodel is closer toreal human but it required around 1 million mesh cells whichwere reduced by almost 5 times for the skin-only-cylinderand rectangle models The simulation time was also reducedby a factor of 10 for the skin-only models The propagationloss (L) is determined from the scattering (119878) parameter 11987821as

119871 (dB) = 20log1011003816100381610038161003816119878211003816100381610038161003816

(2)

where port 1 and port 2 are signifying transmission andreception sides respectively For symmetrical capacitive BCCscenarios |11987812| = |11987821|


(d) Str4

(c) Sk-Rec

Verticalcoupler

(b) Sk-Cyl

(a)

A2

A3A4

(f) Body positions(e)

d

X

Y

Z

8 cm

8 cm

60cm

20cm

20cm

25 cm

25cm

50

cm90

cm

15 cm45 cm

Skin [17mm]Fat [12mm]

Muscle [23mm]

Bone [60mm]

Figure 3 Comparison of different models with couplers (shown for vertical electrodes only) (a) Cross-sectional view of the standard four-layer-stratified (Str4) human arm model (layer thickness is shown in square brackets) (b) skin-only-cylinder (Sk-Cyl) model (c) skin-only-rectangle (Sk-Rec) model (d) standard four-layer-stratified (Str4) model (e) the skin-only-rectangle human body model with all thedimensions and (f) body positions for validation with the measurements from literature

34 Evaluation for NumericalHuman Body Variation Uncer-tainties The proposed efficient full-wave EM simulationapproach has been evaluated by taking the effects of numericuncertainties (boundary conditions mesh cells) and humanbody variation uncertainties (dielectric properties dielectricthicknesses) independentlyThe systematic variations of sim-ulation parameters have been performed for Str4 human armmodel (shown in Figure 4) and skin-only-rectangle human

body model (shown in Figure 6) for both the vertical andhorizontal couplers

341 Numerical Uncertainties

Boundary ConditionsThe added spacing of open added space(OAS) boundary condition (BC) is varied between 18th and12nd of wavelength (at the center frequency of 30MHz) in


Frequency (MHz)

0

05

1

15

2

25

5 10 15 20 25 30 35 40 45 50 6055

Str4 and Sk-Cyl (40 cm)Str4 and Sk-Rec (40 cm)Str4 and Sk-Cyl (90 cm)

Str4 and Sk-Rec (90 cm)Str4 and Sk-Cyl (20 cm)Str4 and Sk-Rec (20 cm)

|Var

iatio

n in

pro

paga

tion

loss|(

dB)

(a)

0

2

4

6

8

10

12

14

16

18

20

Frequency (MHz)5 10 15 20 25 30 35 40 45 50 6055



|Var

iatio

n in

pro

paga

tion

loss|

(dB)

(b)

Figure 4 Variation in propagation loss among three human arm models skin-only-cylinder (Sk-Cyl) skin-only-rectangle (Sk-Rec) andstandard four-layer-stratified (Str4) for distances 20 cm 40 cm and 90 cm with (a) vertical couplers [6 times 6 times 3] (b) horizontal couplers [5 times2 times 1] all coloured symbols show variations with boundary conditions mesh sizes dielectric properties and dielectric layer thicknesses forStr4 human arm model with 40 cm distance

119883 119884 and 119885 directions for the human arm model For thehuman body model in addendum to the above open BC on119884-min (bottom) with OAS in all other directions have beenconsidered denoted as E-OAS

Mesh Cells The increase in mesh cells (3-4 times) from therecommended setting (at least 2-3 mesh lines for the smallestregion) has been considered

342 Human Body Variation Uncertainties

Dielectric Properties The variation of plusmn12 is taken for allthe layers of Str4 human armmodel and skin layer of humanbody model

Dielectric Thickness Almost plusmn17 variation is considered fordifferent combinations of skin fat muscle and bone of Str4human arm model with no thickness variation for humanbody model

Figures 4(a) and 4(b) show the relative difference inpropagation loss variations between Str4 and Sk-CylSk-Recfor vertical and horizontal coupler configurations respec-tively The effect of systematic variations (boundary condi-tions mesh cells dielectric properties and dielectric layerthicknesses) for Str4 human arm model with 40 cm distanceis also shown The dark orange triangle teal red andmagenta coloured symbols show the effect of the consideredvariation of dielectric properties dielectric thickness bound-ary conditions and mesh cells respectively It can also beobserved from the transient solver simulation results shownin Figure 4(a) that the relative difference in propagation

loss variations between standard four-layer-stratified (Str4)and skin-only-rectangle (Sk-Rec) and skin-only-cylinder(Sk-Cyl) is very small (within 25 dB) for vertical couplerconfiguration over 20 cm 40 cm and 90 cm distances from1MHz to 60MHz However for the horizontal coupler con-figuration the difference is comparatively larger (between10 dB to 20 dB) for frequencies between 1MHz and 15MHzbut reduces for frequencies higher than 15MHz as shownin Figure 4(b) This comparison reveals that the skin-only-rectangle arm model is sufficiently accurate for verticalcoupler configuration and can be used for simplificationpurposes However the propagation characteristics due tothe horizontal coplanar couplers are dependent to a largerextent on the dispersive properties of the underlying tissuelayers in the human body model It is worth mentioning herethat the valuable computation time is reduced due to thelesser number ofmesh cellsrsquo requirement inCSTMWS for theskin-only models in comparison with standard four-layer-stratifiedmodel asmentioned earlier Moreover it can also beseen that the effect of curvature for skin-only-cylinder modeldoes not result in significant variation of the propagationloss compared to skin-only-rectangle model for both vertical(2 dB) and horizontal (3 dB) coupler configurations Thesimulations have been performed for skin-only-rectanglehuman body model as well by varying number of mesh cellsboundary conditions and skin dielectric properties for armposition f (135 cm distance) of Figure 7(b) for both verticaland horizontal coupler configurationsThe simulation resultsin Figure 6 show that the error bounds are within theacceptable limits for skin-only-rectangle human bodymodel


Prop

agat

ion

loss

(dB)

40

45

50

55

60

65

70

Frequency (MHz)5 10 15 20 25 30 35 40 45 50 6055

A2A3 EM SIM [4 times 4 times 1]

A2A3 mean of 245 realizations (Philips) [4 times 4 times 1]


A2A4 (Philips) [4 times 4 times 1]

(a)

Prop

agat

ion

loss

(dB)

20

30

40

50

60

70

80

Longitudinal-longitudinal HE (A2A3-EM simulation)Longitudinal-longitudinal HE (A2A3-Philips)Transversal-longitudinal HE (A2A3-EM simulation)Transversal-longitudinal HE (A2A3-Philips)Longitudinal-transversal HE (A2A3-Philips)Transversal-transversal HE (A2A3-Philips)Transversal-transversal HE (A2A3-EM simulation)Longitudinal-transversal HE (A2A3-EM simulation)

Frequency (MHz)5 10 15 20 25 30 35 40 45 50 6055

(b)

Figure 5 3D full-wave EM simulation results compared with Philips measurement results [1 16 17] for the skin-only-rectangle (Sk-Rec)human body model with (a) vertical couplers [4 times 4 times 1] for A2A3 and A2A4 path lengths (the coloured symbols show variations in Philipsmeasurements with respect to coupler dimensions separation construction and body positionmovements) (b) horizontal couplers [5 times 2times 1] having different orientations for A2A3 path length

35 Validation with the Measurement Results It is importantto validate the proposed efficient EM approach based onthe skin-only-rectangle human body model with the mea-surement results on the actual human body The simulationresults of the last subsection also provide the bounds forthe simplified efficient approach for both the vertical andhorizontal couplers Most reported measurement results inthe literature do not represent the real propagation loss ofthe human body This is either due to the usage of earth-grounded lab instruments or the first-order RC pole likeresponse due to analog front-end limitation which masksthe actual human body propagation loss for example [5 721 22] The use of baluns also does not help in completelyisolating the earth grounds as the parasitic capacitancebetween primary and secondary windings causes the cou-pling of common-mode signal [23] It has been shown in[23] that the maximum difference in the transmission levelmagnitudemeasurements is as high as 40 dB for four differenttypes of baluns Some of the examples from the literaturewhich fall under this category of experimental measurementuncertainty are in [24 25] The measurements performedon simplified homogeneous biological human phantomsare not equivalent to real measurements on human bodyThe examples of experimental measurement uncertainty forhuman equivalent phantoms from literature are [26] (muscleequivalent phantom at 10MHz) and [27] (muscle simulating

liquid) However the measured results by Philips researchgrouppresented in [1 16 17] take care of the above-mentionedexperimental setup uncertainties That is why for validationpurposes the estimated propagation loss from the full-waveEM approach for skin-only-rectangle human body model iscompared with the measurement results of Philips researchgroup for both the horizontal and vertical coupling schemes

The geometrical dimensions of the skin-only-rectanglehuman body model are shown in Figure 3(e) and the dimen-sions for horizontal and vertical coupler schemes are takenas reported by Philips [1 16 17] The simulation setup forthe validation is the same as mentioned in Section 33 Forexcitation the wave guide ports have been used as the skin-only model is homogeneous Since the problem with theinclusion of the whole human body becomes computativelylarge local mesh refinements have also been used to reducethe mesh cell requirements The results are simulated forthe two vertical coupler structures on the arm of skin-only-rectangle human body model for different separationdistances of A2A3 and A2A4 The distances for A2A3 andA2A4 positions are taken as 16 cm and 26 cm respectivelyThe simulated A2A3 propagation loss is compared to themean of 245 realizations of Philips measurement results asshown in Figure 5(a) which gives confidence on the Philipsexperimental results and our validation process Althoughelbow joint has not been modeled in A2A4 but if the


additional loss of 4 dB is considered for the elbow joint [10](for larger joints loss is as large as 8 dB) then the deviationbetween the measured and simulated results is less than 3 dBfor A2A4 path length from 1MHz to 60MHz for verticalcoupler configuration The deviation in propagation lossbetween the measured and simulated results for A2A3 pathis less than 3 dB All coloured symbols other than trianglein Figure 5(a) show variations in measured propagation lossfor A2A3 path length for vertical coupler configuration asa function of coupler dimensionsseparation coupler con-struction arm orientations body postures and movementsAll coloured triangular symbols show measured propagationloss variations for A2A4 path length All these variable factorscan be incorporated in our proposed efficient full-wave EMmodel except for body movements

Similarly horizontal coupler structures with longitudinaland transverse orientations have been simulated on the skin-only-rectangle human body model for A2A3 path lengthand compared with Philips measurement results as shown inFigure 5(b) The metallized side of the substrate in the hori-zontal coupler structure touches the human body The max-imum difference between simulated and measured results isaround 15 dB to 18 dB for the horizontal coupler as shown inFigure 5(b) for A2A3 path length which is consistent withthe human arm model variations of Figure 4(b) Howeverthe similar trend is followed in terms of propagation lossfor different orientations for example the longitudinal-longitudinal one has the lowest propagation loss and thetransversal-transversal one has the highest above 20MHz inboth the simulations and measurements

4 Simulation Results for DifferentPositionsUser Scenarios

The validation in the last section for the proposed simplifiedand efficient full-wave EM approach provides the motivationfor further investigating the propagation loss as follows

(1) Effect of horizontal and vertical couplers(2) Effect of body positions coupler size and communi-

cation distance(3) Combined effect of external environment (earth-

grounding and material structures)(4) Effect of ground-plane on resultant electric field

The above-mentioned effects have been simulated for thepropagation loss as discussed below

41 Effect of Horizontal and Vertical Couplers A comparisonof the propagation loss for horizontal and vertical couplers isshown in Figure 6 for selected arm positions of Figure 7(b)The size of horizontal coupler is 55 cm times 85 cm with 15 cmand 25 cm horizontal spacing as shown in Figure 1(b) Thepropagation loss for the vertical coupler of size 4 cm times 4 cmwith vertical spacing of 1 cm is at least 10 dB less comparedto horizontal couplers for the arm position f in Figure 7(b)However the difference in propagation loss between horizon-tal and vertical couplers is less for the arm position c shown in

Prop

agat

ion

loss

(dB)

55

60

65

70

75

80

85

90

Frequency (MHz)5 10 15 20 25 30 35 40 45 50 6055

Arm position c (VE)Arm position f (VE)Arm position c (HE 25 cm)Arm position f (HE 15 cm)Arm position f (HE 25 cm)Fine mesh HE 135 cmOAS BC HE 135 cmminus12 skin HE 135 cm

+12 skin HE 135 cmE-OAS BC HE 135 cm+12 skin VE 135 cmFine mesh VE 135 cmminus12 skin VE 135 cmE-OAS BC VE 135 cmOAS BC VE 135 cm

Figure 6 Comparison between horizontal (HE) and vertical (VE)electrode couplers for selected arm positions of Figure 7(b) Theeffect on propagation loss due to variation of mesh cells boundaryconditions and skin dielectric properties is shown with colouredsymbols for arm position f (135 cm distance)

Figure 7(b) The difference in propagation loss for horizontalcouplers with the stratified model is even higher comparedto the skin-only-rectangle model shown in Figure 4(b)Therefore it could be concluded that the vertical couplershave lesser propagation loss than horizontal couplers for thesame communication distance and similar sizes of couplersAnother effect is of spacing between the horizontal couplersthe greater the horizontal spacing the lesser the propagationloss This can be seen in Figure 6 where the propagationloss due to 25 cm horizontal spacing is almost 2 dB lessthan 15 cm horizontal spacing for the arm position f thearms stretched outward as shown in Figure 7(b) The smallerhorizontal spacing permits higher localized current betweenthe transmitting couplers compared to the receiving couplers[28]

42 Effect of Body Position Coupler Size and CommunicationDistance The effect of different arm positions shown inFigure 7(b) on the propagation loss has been simulated inFigure 7(a) with the vertical coupler configuration Thesesimulation results are for communication distances longerthan 50 cm for which there is limited information availablein the literature The maximum propagation loss is for thearm position a shown in Figure 7(b) with diagonal distanceof 102 cm between transmitting and receiving couplers Thepropagation loss for arm position f due to 135 cm distance


Prop

agat

ion

loss

(dB)

30

40

50

60

70

80

90

100

110

120

Arm position aArm position bArm position c

Arm position dArm position eArm position f

Frequency (MHz)5 10 15 20 25 30 35 40 45 50 55

(a)

180∘ 102 cmArm position a

90∘ 116 cmArm position b

90∘ 116 cmArm position c

0∘ 53 cmArm position d

0∘ 53 cmArm position e

180∘ 135 cmArm position f

Vertical coupler dimensions [4 times 4 times 1]

(b)

Prop

agat

ion

loss

(dB)

30

40

50

60

70

80

90

100

110

120

Body position aBody position bBody position cBody position d

Frequency (MHz)5 10 15 20 25 30 35 40 45 50 55

Body position e [25 cm] [4 times 4 times 05]Body position e [25 cm] [1 times 1 times 05]Body position e [10 cm] [1 times 1 times 05]

(c)

Body position a[4 times 4 times 1] cm 83 cm

Body position eRing [1 times 1 times 05] cm 1025 cm

Body position b[4 times 4 times 1] cm 121 cm

Square pendant

Body position d[3 times 2 times 05] cm 83 cm

Rectangle pendant

Body position c[4 times 4 times 1] cm 155 cm

Wrist watch

TxRx

(d)

Figure 7 Continued


Prop

agat

ion

loss

(dB)

30

40

50

60

70

80

90

100

110

120

Scenario bScenario c

Scenario d [no GND]Scenario d [GND]Scenario eScenario f

Frequency (MHz)5 10 15 20 25 30 35 40 45 50 6055

Scenario a [PL2rarr1]Scenario a [PL1rarr2]

(e)

Vertical coupler dimensions-[4 times 4 times 1]

TxRx

TxRx

1

2Steelcabin

GroundGround-

Ground-plane

Ground- Ground-plane

Ground-plane

Scenario a Scenario b

Scenario c Scenario d

Scenario e Scenario f

Alumini

um ta

ble

Alumini

um to

p

Woo

den t

able

Woo

den to

p

Steel cabin 180∘ 102 cm Aluminium table 53 cm

Aluminium top 53 cm without GND 53 cm

Wooden table 53 cm Wooden top 53 cm

25 cm

Free space with and

plane

plane

(f)

Figure 7 Plots for propagation loss (a) (c) and (e) with vertical coupler configuration for (b) (d) and (f) scenarios respectively

is less compared to arm position a at lower frequenciesthe difference gradually becomes negligible for frequenciesmore than 40MHz Another comparison which emphasizesthe importance of body position is between arm positiond and arm position e (53 cm distance) where the differencein propagation loss is approximately 25 dB at 1MHz and13 dB to 14 dB over the rest of the frequency range Thebetter radiation efficiency for frequencies higher than 15MHzand direct line-of-sight communication together tends toimprove the capacitive return path for arm position d andarm position e The propagation loss is less up to 30MHzfor arm position c compared to arm position b for the samedistance of 116 cm The propagation loss for arm position cfor 116 cm distance is less than the propagation loss for armposition d for 53 cm distance All these simulation resultsindicate that the propagation loss cannot be just scaled upfor the longer communication distance based on the shorterdistance without taking into consideration the specific bodypositions It could also be easily deduced that the bestpositions are when arms are away from the torso region

Body wearables for example wrist watch pendant orring impose limitations on vertical coupler dimensionswhose effect on the propagation loss has been simulated

in Figure 7(c) for different body positions in Figure 7(d)The propagation loss due to body position c having 155 cmdistance is less for body position a with 83 cm distance Thepropagation loss due to body position c (155 cm distance) isalso less than body position b with 121 cm distance

Table 2 summarizes comparison of specific couplerbodypositions in Figures 7(b) and 7(d) for higher propagation lossThis comparison indicates that it is not only the distance butalso the specific body position which matters in determiningthe propagation loss characteristics and we cannot correctlypredict the propagation loss for longer distances based on themeasurements of smaller distances as mentioned earlier

There is a propagation loss of more than 90 dB forfrequencies below 10MHz for rectangle pendant with couplersize of [3 times 2 times 05] vertical spacing for body position dwhich makes the receiver design difficult The requirementof reduced dimensions [1 times 1 times 05] for ring configurationresults in the increased values of propagation loss comparedto [4 times 4 times 05] for same distance of 25 cm for body positione The additional propagation loss of approximately 20 dB atthe communication distance of 25 cm compared to 10 cm forbody position emakes it difficult to design receiver of enoughsensitivity at 10MHz for the coupler dimensions of [1 times 1 times


Table 2 Comparison of specific couplerbody positions in Figures7(b) and 7(d) for higher propagation loss

Couplerbodyposition 1


Comparisonbetween

positions 1 and 2for higher

propagation loss

Arm position a(102 cm) mdash

Maximumpropagation loss

for armpositions inFigure 7(b)

Arm position f(135 cm)

Arm position a(102 cm) Arm position a

Arm position d(53 cm)

Arm position e(53 cm) Arm position d

Arm position c(116 cm)

Arm position b(116 cm) Arm position b


Arm position d(53 cm) Arm position d

Body position c(155 cm)

Body position a(83 cm) Body position a


Body position b(121 cm) Body position b

05] Therefore it can be inferred that minimum dimensionsof the coupler are determined by different types of bodywear-ables The coupler dimensions dictate the receiver sensitivityand the communication distance

43 Combined Effect of External Environment (Earth-Ground-ing Material Structures) The effects on the propagation lossdue to external furniture like wood aluminium or steel havebeen simulated in Figure 7(e) for scenarios in Figure 7(f)Thehorizontal ground-plane does not have the same effect on thepropagation loss for different furniturematerials which couldbe either conductors or insulators The values of complexpermittivity for these materials have been used from thebuilt-in database provided by CST MWS for example thedispersive value of 12059810158401015840 for wood varies exponentially betweenmaximum 215 at 1MHz and minimum 05 at 60MHzwhile 1205981015840 has a constant value of approximately 25 over theentire frequency range Aluminium has superior conductiveproperties than both stainless steel and wood

The aluminium table top in Scenario c provides a directconductive path between transmitter and receiver couplersresulting in the lower propagation loss than arm position ein Figure 7(b) for the same distance of 53 cm The radiatedpower starts becoming dominant for frequencies greaterthan 15MHz which further lowers the propagation loss Thepropagation loss for grounded aluminium table in Scenariob increases for frequencies up to 30MHz compared toaluminium top in Scenario b This effect could probably beexplained by the additional signal loss due to the forma-tion of closed loop through conductive aluminium table to

ground-plane But the radiated power which starts becomingdominant at higher frequencies compensates the effect ofsignal loss beyond 30MHz for both Scenario b and Scenarioc The higher propagation loss could be observed in case ofwooden tabletop in Scenario e and Scenario f compared toaluminium tabletop due to poor conductive properties ofwood The ground-plane has negligible effect on the propa-gation loss in case of closed loop formed by wooden table inScenario e compared to wooden table top in Scenario f Theeffect of greater radiated power in lowering propagation losscan be observed for higher frequenciesThe external furniturecould also result in asymmetrical propagation loss as shownfor the grounded steel cupboard in Scenario a when thetransmitter and receiver couplers change their positions from1 to 2 The horizontal ground-plane and vertical groundedsteel cupboard have lowering effect on the propagation losswhen compared with Arm Position a in Figure 7(b) Airwhich is a poor conductor has maximum propagation lossfor Scenario d shown in Figure 7(f) for the same distanceof 53 cm The simulated results in Figure 7(e) infer thatthe ground-plane has negligible effect on the propagationloss for insulators with dielectric properties like wood evenwhen they make a closed loop between transmitting andreceiving couplers with ground-plane However for metallicconductors for example aluminium the direct path betweentransmitting and receiving couplers compensate additionalsignal loss due to closed loop formed with the ground-planeThis signal loss is compensated by increased radiated powerat higher frequencies

44 Effect of Ground-Plane on the Resultant Electric FieldThe electric field intensity plots are shown for a single cutalong 119911-axis at 10MHz frequency in Figure 8 so that thedistribution of electric field in 2D along 119909119910 plane (area 305times 261 cm2) can be observed There is a direct correlationbetween the propagation loss at 10MHz in Figure 7(e) andthe corresponding color mapping of E-field intensity plots inFigure 8 The electric field at the transmitter coupler is zerodB in these E-field plots

The asymmetrical electric field distribution for Scenario adue to change in transmitting and receiving coupler positionsis evident in electric field distribution plots The conduc-tive nature of aluminium provides a direct coupling pathbetween transmitting and receiving couplers for Scenario b(aluminium table) compared to Scenario e (wooden table)The grounded aluminium table disturbs the electric fielddistribution below the table top more than the wooden tableThe ground-plane under human model has almost no effecton the electric field distribution in Scenario e with woodentable compared to Scenario e without wooden table Thisalso shows that the ground-plane has negligible effect onthe human body in terms of electric field distribution orpropagation loss The normalized electric field intensity forair medium at the receiver coupler is approximately minus100 dBwhereas it is minus70 dB for Scenario e with human model in theabsence of wooden table This shows that human body is anenergy efficient channel for signal transmission as comparedto wireless transmission through air


x

y

z

minus203

minus328

minus453

minus578

minus703

minus828

minus100

0

(dB)

[Scenario b] with aluminium table [Scenario d] air with no ground-plane

[Scenario e] with wooden table [Scenario e] without wooden table

261

cm261

cm

261

cm261

cm

261

cm261

cm305 cm 305 cm 305 cm

305 cm 305 cm 305 cm

[Scenario a] [PL2rarr1]


Figure 8 Electric field intensity plots showing distribution in 119909119910 plane (a single cut along 119911-axis) for selected scenarios in Figure 7(f)

45 Link-Budget Requirement for BCC The motivationbehind this close to real environment modeling and simu-lation is to find the link-budget requirement for designingcapacitive BCC system in CMOS technologies The designconsiderations include all possible scenarios especially forthe body wearable devices and estimated propagation losseswhich differ for a wide range of body positions communi-cation distances coupler configuration and sizes The maxi-mum available transmitted power 119875Tx could be determinedfrom foundry IO pads which include features like elec-trostatic discharge (ESD) protection essential for capacitiveBCC scenarios when we are deliberately touching As anexample the maximum current for analog IO pads withESD protection is 8mA for 25 V supply for 65 nm CMOStechnology which gives 119875Tx of 13 dBm The propagation lossof human body 119871HB for arm positions b to f in Figure 7(b)is almost 80 dB at 10MHz (Figure 7(a)) for the verticalcoupler configuration with [4 times 4 times 1] dimensions Thiscoupler dimension is suitable for wrist watch as a bodywearable device So under perfectmatching conditions on thetransmitter (Tx) and receiver (Rx) side the received power119875Rx at the reception coupler can be estimated as follows

119875Rx (dBm) = 119875Tx (dBm) minus 119871HB (dB)

119875Rx (dBm) = 13 (dBm) minus 80 (dB) = minus 67 (dBm) (3)

This means that the receiver should be sensitive enoughto detect a minimum signal level of minus67 dBm to cover thepropagation loss due to arm positions b to f in Figure 7(b) at10MHz frequency

5 Conclusion

A systematic efficient approach based on simplified humanmodeling and full-wave EM simulation has been proposedto realistically analyze the interaction of coupler the humanbody (considering electrophysiological properties of tissues)and the environment all together for investigating the link-budget requirement for designing capacitive body-coupledcommunication system The full-wave EM simulation strat-egy has been evaluated for numeric uncertainties (boundaryconditions mesh cells) and human body variation uncer-tainties (dielectric properties dielectric thicknesses) inde-pendently for both vertical and horizontal couplers Aftervalidating with themeasurement results the propagation lossfor twenty different body positions in the mid-frequencyrange of 1MHz to 60MHz with communication distancesup to 155 cm has been simulated It is shown that the skin-only-rectangle human body model is accurate enough topredict the propagation loss for vertical couplers within 2 dBwhile the horizontal couplers have precision within 10 dBto 15 dB Table 2 compares specific couplerbody positionswhich shows that the propagation loss characteristics areaffected not only by the distance but also by the specific bodypositions and the propagation loss cannot be just scaled upfor the longer communication distances based on the shorterdistances The comparison shows that the propagation lossin the arm-torso-arm region is the lowest when arms are nottouching the torso region irrespective of the distance Theground-plane has limited lowering effect on the propagationloss except when it has direct coupling with either transmitteror receiver coupler in the presence of metallic structuresThe


coupler dimensions are determined by the requirement ofbody wearable device which dictates the propagation lossThe link-budget has been investigated more realistically as aresult of presented modeling and simulation approach

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

References

[1] H Baldus S Corroy A Fazzi K Klabunde and T SchenkldquoHuman-centric connectivity enabled by body-coupled com-municationsrdquo IEEE Communications Magazine vol 47 no 6pp 172ndash178 2009

[2] S-J Song N Cho S Kim J Yoo and H-J Yoo ldquoA 2Mbswideband pulse transceiver with direct-coupled interface forhuman body communicationsrdquo in Proceedings of the IEEEInternational Solid-State Circuits Conference (ISSCC rsquo06) pp2278ndash2287 IEEE San Francisco Calif USA February 2006

[3] A Fazzi S Ouzounov and J van den Homberg ldquoA 275mWwideband correlation-based transceiver for body-coupled com-municationrdquo in Proceedings of the IEEE International Solid-StateCircuits ConferencemdashDigest of Technical Papers (ISSCC rsquo09) pp204ndash205 San Francisco Calif USA February 2009

[4] T G Zimmerman ldquoPersonal area networks Near-field intra-body communicationrdquo IBM Systems Journal vol 35 no 3-4 pp609ndash617 1996

[5] N Cho J Yoo S-J Song J Lee S Jeon and H-J YooldquoThe human body characteristics as a signal transmissionmedium for intrabody communicationrdquo IEEE Transactions onMicrowaveTheory and Techniques vol 55 no 5 pp 1080ndash10852007

[6] J Bae H Cho K Song H Lee andH-J Yoo ldquoThe signal trans-mission mechanism on the surface of human body for bodychannel communicationrdquo IEEE Transactions on MicrowaveTheory and Techniques vol 60 no 3 pp 582ndash593 2012

[7] K Hachisuka Y Terauchi Y Kishi et al ldquoSimplified cir-cuit modeling and fabrication of intrabody communicationdevicesrdquo Sensors and Actuators A Physical vol 130-131 pp322ndash330 2006

[8] N Haga K Saito M Takahashi and K Ito ldquoProper derivationof equivalent-circuit expressions of intra-body communicationchannels using quasi-static fieldrdquo IEICE Transactions on Com-munications vol E-95-B no 1 pp 51ndash59 2012

[9] N Haga K Saito M Takahashi and K Ito ldquoEquivalent circuitof intrabody communication channels inducing conductioncurrents inside the human bodyrdquo IEEE Transactions on Anten-nas and Propagation vol 61 no 5 pp 2807ndash2816 2013

[10] M S Wegmueller A Kuhn J Froehlich et al ldquoAn attempt tomodel the human body as a communication channelrdquo IEEETransactions on Biomedical Engineering vol 54 no 10 pp 1851ndash1857 2007

[11] K Fujii and Y Okumura ldquoEffect of earth ground and envi-ronment on body-centric communications in the MHz bandrdquoInternational Journal of Antennas and Propagation vol 2012Article ID 243191 10 pages 2012

[12] K Norton ldquoThe propagation of radio waves over the surface ofthe earth and in the upper atmosphererdquo Proceedings of the IREvol 24 no 10 pp 1367ndash1387 1936

[13] K Norton ldquoThe propagation of radio waves over the surfaceof the earth and in the upper atmosphererdquo Proceedings of theInstitute of Radio Engineers vol 25 no 9 pp 1203ndash1236 1937

[14] S Gabriel R W Lau and C Gabriel ldquoThe dielectric propertiesof biological tissues III Parametric models for the dielectricspectrum of tissuesrdquo Physics in Medicine and Biology vol 41no 11 pp 2271ndash2293 1996

[15] IFAC-CNR An Internet Resource for the Calculation ofthe Dielectric Properties of Body Tissues in the FrequencyRange 10Hzndash100GHz IFAC-CNR Florence Italy 1997httpniremfifaccnrittissprop

[16] T C W Schenk N S Mazloum L Tan and P Rutten ldquoExper-imental characterization of the body-coupled communicationschannelrdquo in Proceedings of the IEEE International Symposiumon Wireless Communication Systems (ISWCS rsquo08) pp 234ndash239October 2008

[17] N S Mazloum Body-coupled communications experimentalcharacterization channel modeling and physical layer design[MS thesis] Department of Signals and Systems DistributedSensor Systems Chalmers University of Technology PhilipsResearch Gothenburg Sweden 2008

[18] Computer Simulation Technology (CST) 2015 httpwwwcstcom

[19] M Clemens and T Weiland ldquoDiscrete electromagnetism withthe finite integration techniquerdquo Progress in ElectromagneticsResearch vol 32 pp 65ndash87 2001

[20] Y Song K Zhang Q Hao L Hu J Wang and F ShangldquoA finite-element simulation of galvanic coupling intra-bodycommunication based on the whole human bodyrdquo Sensors vol12 no 10 pp 13567ndash13582 2012

[21] J A Ruiz and S Shimamoto ldquoExperimental evaluation of bodychannel response and digital modulation schemes for intra-body communicationsrdquo in Proceedings of the IEEE InternationalConference on Communications (ICC rsquo06) vol 1 pp 349ndash354IEEE Istanbul Turkey June 2006

[22] R Xu H Zhu and J Yuan ldquoElectric-field intrabody commu-nication channel modeling with finite-element methodrdquo IEEETransactions on Biomedical Engineering vol 58 no 3 pp 705ndash712 2011

[23] J Sakai L-S Wu H-C Sun and Y-X Guo ldquoBalunrsquos effect onthe measurement of transmission characteristics for intrabodycommunication channelrdquo in Proceedings of the IEEE MTT-S International Microwave Workshop Series on RF and Wire-less Technologies for Biomedical and Healthcare Applications(IMWS-BIO rsquo13) pp 1ndash3 December 2013

[24] R Xu H Zhu and J Yuan ldquoCircuit-coupled FEM analysisof the electric-field type intra-body communication channelrdquoin Proceedings of the IEEE Biomedical Circuits and SystemsConference (BioCAS rsquo09) pp 221ndash224 November 2009

[25] H Zhu R Xu and J Yuan ldquoHigh speed intra-body com-munication for personal health carerdquo in Proceedings of theAnnual International Conference of the IEEE Engineering inMedicine and Biology Society (EMBC rsquo09) pp 709ndash712 IEEEMinneapolis Minn USA September 2009

[26] K Fujii M Takahashi and K Ito ldquoElectric field distributionsof wearable devices using the human body as a transmissionchannelrdquo IEEE Transactions on Antennas and Propagation vol55 no 7 pp 2080ndash2087 2007

[27] M S Wegmueller S Huclova J Froehlich et al ldquoGalvaniccoupling enabling wireless implant communicationsrdquo IEEE


Transactions on Instrumentation and Measurement vol 58 no8 pp 2618ndash2625 2009

[28] M S Wegmuller Intra-body communication for biomedi-cal sensor networks [PhD thesis] Eidgenossische TechnischeHochschule ETH Zurich Switzerland 2007

International Journal of

AerospaceEngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

RoboticsJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014


Active and Passive Electronic Components

Control Scienceand Engineering

Journal of



RotatingMachinery


Hindawi Publishing Corporation httpwwwhindawicom

Journal ofEngineeringVolume 2014

Submit your manuscripts athttpwwwhindawicom

VLSI Design



Shock and Vibration


Civil EngineeringAdvances in

Acoustics and VibrationAdvances in



Electrical and Computer Engineering

Journal of

Advances inOptoElectronics


Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

SensorsJournal of


Modelling amp Simulation in EngineeringHindawi Publishing Corporation httpwwwhindawicom Volume 2014


Chemical EngineeringInternational Journal of Antennas and

Propagation




Navigation and Observation



DistributedSensor Networks



and analyze the capacitive BCC channel This paper pro-poses a systematic efficient full-wave electromagnetic (EM)approach to analyze capacitive BCC channel propagationloss characteristics and the influence of the aforesaid factorsThe analysis after validation with the measurement resultsconsiders the combined interaction of the capacitive couplerof different types and sizes the human body (electrophysio-logical properties of tissues) and the environment to explainpropagation loss for complex scenarios Moreover differentbody positions have also been analyzed over the usefulfrequency range of 1MHz to 60MHz for communicationdistances longer than 50 cm

This paper is divided into five sections Section 2 presentsan overview and comparison of the literature about themodeling of capacitive BCC channel Section 3 describesthe proposed efficient full-wave EM approach for analyzingcapacitive BCC The evaluation for numericalhuman bodyvariation uncertainties and validation with the measurementresults from the literature of the proposed approach is alsopresented in this section The effects of coupler configura-tions human body and the environment are estimated fromthe propagation loss curves and the electric field intensityplots which defines the scope of Section 4 The investigationof link-budget requirement based on the estimated propaga-tion loss is also carried out in this section followed by theconcluding remarks in Section 5

2 Literature Review Modeling of CapacitiveBCC Channel

Different propagation models for capacitive BCC channelhave been proposed in the literature with confined applicablescope Zimmerman [4] who pioneered this field presentedan electrical model which is based on electrostatic cou-pling between transmitter (Tx) and receiver (Rx) capac-itive electrodes and their capacitive return path throughexternal ground considering the human body as a perfectelectric conductor (PEC) with zero impedance This lumpedcapacitive model has been extended to a distributed parallelRC equivalent circuit model [5] The values of resistance(119877) and capacitance (119862) in this model have been derivedfrom the equivalent homogeneous human phantom modelof muscle for arm-torso-arm region considering conductioncurrent and voltage drop inside human body The limitationwith Zimmerman model [4] is that it perhaps takes intoaccount one particular scenario for empirically calculatingthe body and electrode capacitance from measured pathimpedance (possibly some typical values were also usedin the model whose adapted strategy for estimation is notclearly known) Similarly distributed RC parallel circuitvalues in [5] have been empirically calculated from theconsidered homogeneous phantom model (120590 = 02 Sm amp120598119903= 70) for one particular scenario Moreover the earth-

grounded instruments used in [5] also raises questions on theapplicability of these derived circuit parameters for practicalscenariosThe lumped coupling capacitance values suggestedin the Zimmerman model were estimated numerically in[7ndash9] Reference [7] proposed a four-terminal equivalent

circuit model with six impedances for two- and four-electrode arrangements The capacitance was determinednumerically under the electrostatic assumption using finiteelement method (FEM) The transmission gain calculatedby this circuit model was compared with the measuredresults at 1 kHz 10 kHz 100 kHz and 1000 kHz but theinstruments used in the measurement were not battery-operated but rather earth-grounded thereby indirectly shar-ing the common ground Another equivalent circuit modelpresented in [8] numerically calculated the mutual capac-itance for different scenarios by the method-of-moments(MoM) which were also verified by finite-difference time-domain (FDTD) method The different scenarios includeno-conductor grounded body grounded and transmitteror receiver grounded under quasi-electrostatic assumptionconsidering human body as a perfect electrically conductingsphere with negligible induced currents This model wasrefined in [9] by proposing an equivalent circuit model basedon lossy conductors inducing conduction currents inside thehuman arm phantomThe capacitance values were estimatedby the numerical analysis technique of MoM and verifiedby FDTD The relative permittivity and conductivity of thehuman armphantomused in [9] correspond to that of humanmuscle tissue onlyThe capacitance due to the outermost skinand fat dielectric layers have not been taken into consider-ation (while evaluating the equivalent lumped capacitance)The conductivity of muscle tissue is higher than outermostskin and fat tissues which undermines the proposed modelReference [6] has considered the surface of human body as aninfinite half-planewith skin-only tissue properties for verticalelectric-dipole type coupler The analytical model [6] usesthe derivation in [12 13] for defining the vertical componentof the electric field intensity due to the vertical dipole Theelectric field intensity expression after simplification includesthe surfacewave far-field propagationwith attenuation factorreactive inductive field radiation and quasi-static near-fieldtermsThis model takes into account the electrophysiologicalproperties in terms of relative permittivity and conductiv-ity of the human skin which is explicitly included in theexpression of surface wave attenuation factor But on theother hand this model generalizes the finite-sized verticalcoupler configuration with a theoretical infinitesimal dipolewhich results in deviation between theoretical and measuredresults and ismore pronouncedwhen the coupler dimensionsand communication distances are comparable Reference[10] considered the electrophysiological properties of skinand underneath living tissues in 3D finite element modelof human upper arm under quasi-electrostatic conditionsto study the attenuation characteristics but their study waslimited to 1MHzThe dielectric values used in this simulationmodel from [14] have larger uncertainties than average forfrequencies below 1MHz Moreover the effects of externalenvironment and earth-ground on the signal or propagationloss have also not been presented Reference [11] consideredthe combined effect of coupler muscle equivalent humanbody model and environment (earth-ground and materialstructures) at 10MHz but the simulation results are limitedto fixed size coupler fixed distance (19 cm) between couplersand same body position


Metal

Metal

Airdielectric

1 cm

4 cm

4 cm


85 cm

55 cm

15 cm

25 cm















onof

ther

eviewed

literaturec

oncerningthem

odelingof

capacitiv

eBCC

channel

Literature

review

[reference]

BCCprop

agation

mod

el

Coverageo

fmod

elingaspects

Mod

elcoverin

gdifferent

scenarios

Cosim

ulation

mod

elcirc

uit

provision

Com

putatio

nal

efficiency

Cou

pler

sizesty

pes

Body

tissues

physiology

Environm

ent

Body

positions

Frequency(1to

60MHz)

TxRxdistance

ge50

cm

[45]

Equivalent

circuit

Fixedsiz

e[4]

no[5]n

oNo[4]

phantom

[5]

No

No

No[4]10

to60

MHz[5]

No[4]yes[5]

Yes

Yes

[7ndash9

]RC

estim

ate

MOMFDTD

Noyes[7]no

Nomuscle

equivalent

[9]

No

No

No

No

Yes

Partial

[6]

Analytic

al(curve-fitting)

Infin

itesim

aldipo

leno

Skin-only

No

No

Yes

Yes

No

Yes

[10]

FEM

quasi-e

lectrosta

ticFixedsiz

eno

Skin-only

No

Yes

No

No

Not

mentio

ned

Partial

[11]

FDTD

Fixedsiz

eno

Muscle

equivalent

Yes

No

No

No

Not

mentio

ned

Partial

Thiswork

Efficientfull-w

ave

EMVa

riables

izeyes

Stratifi

edamp

skin-only

Yes

Yes

Yes

Yes

Yes(119878-m

atrix

)Partiallowast

lowast

Full-waveE

Misan

umericaltechniqu

ecompu

tativ

elyintensiveho

weveranapproach

ofmakingiteffi







119903)


1205981015840

= 1205980120598119903

12059810158401015840

= 1205981015840 tan 120575

tan 120575 =120590119890

21205871198911205981015840

(1)



5 10 15 20 25 30 35 40 45 50 55

5 10 15 20 25 30 35 40 45 50 55Frequency (MHz)

104

103

102

101

104

103

102

101

Nor

mal

ized

(120598998400 )

Nor

mal

ized

(120598998400998400

)







119871 (dB) = 20log1011003816100381610038161003816119878211003816100381610038161003816

(2)



(d) Str4

(c) Sk-Rec

Verticalcoupler

(b) Sk-Cyl

(a)

A2

A3A4


d

X

Y

Z

8 cm

8 cm

60cm

20cm

20cm

25 cm

25cm

50

cm90

cm

15 cm45 cm


Muscle [23mm]

Bone [60mm]







Frequency (MHz)

0

05

1

15

2

25

5 10 15 20 25 30 35 40 45 50 6055



|Var

iatio

n in

pro

paga

tion

loss|(

dB)

(a)

0

2

4

6

8

10

12

14

16

18

20

Frequency (MHz)5 10 15 20 25 30 35 40 45 50 6055



|Var

iatio

n in

pro

paga

tion

loss|

(dB)

(b)










Prop

agat

ion

loss

(dB)

40

45

50

55

60

65

70

Frequency (MHz)5 10 15 20 25 30 35 40 45 50 6055





(a)

Prop

agat

ion

loss

(dB)

20

30

40

50

60

70

80


Frequency (MHz)5 10 15 20 25 30 35 40 45 50 6055

(b)















Prop

agat

ion

loss

(dB)

55

60

65

70

75

80

85

90

Frequency (MHz)5 10 15 20 25 30 35 40 45 50 6055







Prop

agat

ion

loss

(dB)

30

40

50

60

70

80

90

100

110

120



Frequency (MHz)5 10 15 20 25 30 35 40 45 50 55

(a)








(b)

Prop

agat

ion

loss

(dB)

30

40

50

60

70

80

90

100

110

120


Frequency (MHz)5 10 15 20 25 30 35 40 45 50 55


(c)




Square pendant


Rectangle pendant


Wrist watch

TxRx

(d)

Figure 7 Continued


Prop

agat

ion

loss

(dB)

30

40

50

60

70

80

90

100

110

120



Frequency (MHz)5 10 15 20 25 30 35 40 45 50 6055


(e)


TxRx

TxRx

1

2Steelcabin

GroundGround-

Ground-plane


Ground-plane




Alumini

um ta

ble

Alumini

um to

p

Woo

den t

able

Woo

den to

p




25 cm

Free space with and

plane

plane

(f)











Comparisonbetween


propagation loss























x

y

z

minus203

minus328

minus453

minus578

minus703

minus828

minus100

0

(dB)



261

cm261

cm

261

cm261

cm

261

cm261

cm305 cm 305 cm 305 cm

305 cm 305 cm 305 cm








5 Conclusion






References

































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










Metal

Metal

Airdielectric

1 cm

4 cm

4 cm


85 cm

55 cm

15 cm

25 cm















onof

ther

eviewed

literaturec

oncerningthem

odelingof

capacitiv

eBCC

channel

Literature

review

[reference]

BCCprop

agation

mod

el

Coverageo

fmod

elingaspects

Mod

elcoverin

gdifferent

scenarios

Cosim

ulation

mod

elcirc

uit

provision

Com

putatio

nal

efficiency

Cou

pler

sizesty

pes

Body

tissues

physiology

Environm

ent

Body

positions

Frequency(1to

60MHz)

TxRxdistance

ge50

cm

[45]

Equivalent

circuit

Fixedsiz

e[4]

no[5]n

oNo[4]

phantom

[5]

No

No

No[4]10

to60

MHz[5]

No[4]yes[5]

Yes

Yes

[7ndash9

]RC

estim

ate

MOMFDTD

Noyes[7]no

Nomuscle

equivalent

[9]

No

No

No

No

Yes

Partial

[6]

Analytic

al(curve-fitting)

Infin

itesim

aldipo

leno

Skin-only

No

No

Yes

Yes

No

Yes

[10]

FEM

quasi-e

lectrosta

ticFixedsiz

eno

Skin-only

No

Yes

No

No

Not

mentio

ned

Partial

[11]

FDTD

Fixedsiz

eno

Muscle

equivalent

Yes

No

No

No

Not

mentio

ned

Partial

Thiswork

Efficientfull-w

ave

EMVa

riables

izeyes

Stratifi

edamp

skin-only

Yes

Yes

Yes

Yes

Yes(119878-m

atrix

)Partiallowast

lowast

Full-waveE

Misan

umericaltechniqu

ecompu

tativ

elyintensiveho

weveranapproach

ofmakingiteffi







119903)


1205981015840

= 1205980120598119903

12059810158401015840

= 1205981015840 tan 120575

tan 120575 =120590119890

21205871198911205981015840

(1)



5 10 15 20 25 30 35 40 45 50 55

5 10 15 20 25 30 35 40 45 50 55Frequency (MHz)

104

103

102

101

104

103

102

101

Nor

mal

ized

(120598998400 )

Nor

mal

ized

(120598998400998400

)







119871 (dB) = 20log1011003816100381610038161003816119878211003816100381610038161003816

(2)



(d) Str4

(c) Sk-Rec

Verticalcoupler

(b) Sk-Cyl

(a)

A2

A3A4


d

X

Y

Z

8 cm

8 cm

60cm

20cm

20cm

25 cm

25cm

50

cm90

cm

15 cm45 cm


Muscle [23mm]

Bone [60mm]







Frequency (MHz)

0

05

1

15

2

25

5 10 15 20 25 30 35 40 45 50 6055



|Var

iatio

n in

pro

paga

tion

loss|(

dB)

(a)

0

2

4

6

8

10

12

14

16

18

20

Frequency (MHz)5 10 15 20 25 30 35 40 45 50 6055



|Var

iatio

n in

pro

paga

tion

loss|

(dB)

(b)










Prop

agat

ion

loss

(dB)

40

45

50

55

60

65

70

Frequency (MHz)5 10 15 20 25 30 35 40 45 50 6055





(a)

Prop

agat

ion

loss

(dB)

20

30

40

50

60

70

80


Frequency (MHz)5 10 15 20 25 30 35 40 45 50 6055

(b)















Prop

agat

ion

loss

(dB)

55

60

65

70

75

80

85

90

Frequency (MHz)5 10 15 20 25 30 35 40 45 50 6055







Prop

agat

ion

loss

(dB)

30

40

50

60

70

80

90

100

110

120



Frequency (MHz)5 10 15 20 25 30 35 40 45 50 55

(a)








(b)

Prop

agat

ion

loss

(dB)

30

40

50

60

70

80

90

100

110

120


Frequency (MHz)5 10 15 20 25 30 35 40 45 50 55


(c)




Square pendant


Rectangle pendant


Wrist watch

TxRx

(d)

Figure 7 Continued


Prop

agat

ion

loss

(dB)

30

40

50

60

70

80

90

100

110

120



Frequency (MHz)5 10 15 20 25 30 35 40 45 50 6055


(e)


TxRx

TxRx

1

2Steelcabin

GroundGround-

Ground-plane


Ground-plane




Alumini

um ta

ble

Alumini

um to

p

Woo

den t

able

Woo

den to

p




25 cm

Free space with and

plane

plane

(f)











Comparisonbetween


propagation loss























x

y

z

minus203

minus328

minus453

minus578

minus703

minus828

minus100

0

(dB)



261

cm261

cm

261

cm261

cm

261

cm261

cm305 cm 305 cm 305 cm

305 cm 305 cm 305 cm








5 Conclusion






References

































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation











onof

ther

eviewed

literaturec

oncerningthem

odelingof

capacitiv

eBCC

channel

Literature

review

[reference]

BCCprop

agation

mod

el

Coverageo

fmod

elingaspects

Mod

elcoverin

gdifferent

scenarios

Cosim

ulation

mod

elcirc

uit

provision

Com

putatio

nal

efficiency

Cou

pler

sizesty

pes

Body

tissues

physiology

Environm

ent

Body

positions

Frequency(1to

60MHz)

TxRxdistance

ge50

cm

[45]

Equivalent

circuit

Fixedsiz

e[4]

no[5]n

oNo[4]

phantom

[5]

No

No

No[4]10

to60

MHz[5]

No[4]yes[5]

Yes

Yes

[7ndash9

]RC

estim

ate

MOMFDTD

Noyes[7]no

Nomuscle

equivalent

[9]

No

No

No

No

Yes

Partial

[6]

Analytic

al(curve-fitting)

Infin

itesim

aldipo

leno

Skin-only

No

No

Yes

Yes

No

Yes

[10]

FEM

quasi-e

lectrosta

ticFixedsiz

eno

Skin-only

No

Yes

No

No

Not

mentio

ned

Partial

[11]

FDTD

Fixedsiz

eno

Muscle

equivalent

Yes

No

No

No

Not

mentio

ned

Partial

Thiswork

Efficientfull-w

ave

EMVa

riables

izeyes

Stratifi

edamp

skin-only

Yes

Yes

Yes

Yes

Yes(119878-m

atrix

)Partiallowast

lowast

Full-waveE

Misan

umericaltechniqu

ecompu

tativ

elyintensiveho

weveranapproach

ofmakingiteffi







119903)


1205981015840

= 1205980120598119903

12059810158401015840

= 1205981015840 tan 120575

tan 120575 =120590119890

21205871198911205981015840

(1)



5 10 15 20 25 30 35 40 45 50 55

5 10 15 20 25 30 35 40 45 50 55Frequency (MHz)

104

103

102

101

104

103

102

101

Nor

mal

ized

(120598998400 )

Nor

mal

ized

(120598998400998400

)







119871 (dB) = 20log1011003816100381610038161003816119878211003816100381610038161003816

(2)



(d) Str4

(c) Sk-Rec

Verticalcoupler

(b) Sk-Cyl

(a)

A2

A3A4


d

X

Y

Z

8 cm

8 cm

60cm

20cm

20cm

25 cm

25cm

50

cm90

cm

15 cm45 cm


Muscle [23mm]

Bone [60mm]







Frequency (MHz)

0

05

1

15

2

25

5 10 15 20 25 30 35 40 45 50 6055



|Var

iatio

n in

pro

paga

tion

loss|(

dB)

(a)

0

2

4

6

8

10

12

14

16

18

20

Frequency (MHz)5 10 15 20 25 30 35 40 45 50 6055



|Var

iatio

n in

pro

paga

tion

loss|

(dB)

(b)










Prop

agat

ion

loss

(dB)

40

45

50

55

60

65

70

Frequency (MHz)5 10 15 20 25 30 35 40 45 50 6055





(a)

Prop

agat

ion

loss

(dB)

20

30

40

50

60

70

80


Frequency (MHz)5 10 15 20 25 30 35 40 45 50 6055

(b)















Prop

agat

ion

loss

(dB)

55

60

65

70

75

80

85

90

Frequency (MHz)5 10 15 20 25 30 35 40 45 50 6055







Prop

agat

ion

loss

(dB)

30

40

50

60

70

80

90

100

110

120



Frequency (MHz)5 10 15 20 25 30 35 40 45 50 55

(a)








(b)

Prop

agat

ion

loss

(dB)

30

40

50

60

70

80

90

100

110

120


Frequency (MHz)5 10 15 20 25 30 35 40 45 50 55


(c)




Square pendant


Rectangle pendant


Wrist watch

TxRx

(d)

Figure 7 Continued


Prop

agat

ion

loss

(dB)

30

40

50

60

70

80

90

100

110

120



Frequency (MHz)5 10 15 20 25 30 35 40 45 50 6055


(e)


TxRx

TxRx

1

2Steelcabin

GroundGround-

Ground-plane


Ground-plane




Alumini

um ta

ble

Alumini

um to

p

Woo

den t

able

Woo

den to

p




25 cm

Free space with and

plane

plane

(f)











Comparisonbetween


propagation loss























x

y

z

minus203

minus328

minus453

minus578

minus703

minus828

minus100

0

(dB)



261

cm261

cm

261

cm261

cm

261

cm261

cm305 cm 305 cm 305 cm

305 cm 305 cm 305 cm








5 Conclusion






References

































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation














119903)


1205981015840

= 1205980120598119903

12059810158401015840

= 1205981015840 tan 120575

tan 120575 =120590119890

21205871198911205981015840

(1)



5 10 15 20 25 30 35 40 45 50 55

5 10 15 20 25 30 35 40 45 50 55Frequency (MHz)

104

103

102

101

104

103

102

101

Nor

mal

ized

(120598998400 )

Nor

mal

ized

(120598998400998400

)







119871 (dB) = 20log1011003816100381610038161003816119878211003816100381610038161003816

(2)



(d) Str4

(c) Sk-Rec

Verticalcoupler

(b) Sk-Cyl

(a)

A2

A3A4


d

X

Y

Z

8 cm

8 cm

60cm

20cm

20cm

25 cm

25cm

50

cm90

cm

15 cm45 cm


Muscle [23mm]

Bone [60mm]







Frequency (MHz)

0

05

1

15

2

25

5 10 15 20 25 30 35 40 45 50 6055



|Var

iatio

n in

pro

paga

tion

loss|(

dB)

(a)

0

2

4

6

8

10

12

14

16

18

20

Frequency (MHz)5 10 15 20 25 30 35 40 45 50 6055



|Var

iatio

n in

pro

paga

tion

loss|

(dB)

(b)










Prop

agat

ion

loss

(dB)

40

45

50

55

60

65

70

Frequency (MHz)5 10 15 20 25 30 35 40 45 50 6055





(a)

Prop

agat

ion

loss

(dB)

20

30

40

50

60

70

80


Frequency (MHz)5 10 15 20 25 30 35 40 45 50 6055

(b)















Prop

agat

ion

loss

(dB)

55

60

65

70

75

80

85

90

Frequency (MHz)5 10 15 20 25 30 35 40 45 50 6055







Prop

agat

ion

loss

(dB)

30

40

50

60

70

80

90

100

110

120



Frequency (MHz)5 10 15 20 25 30 35 40 45 50 55

(a)








(b)

Prop

agat

ion

loss

(dB)

30

40

50

60

70

80

90

100

110

120


Frequency (MHz)5 10 15 20 25 30 35 40 45 50 55


(c)




Square pendant


Rectangle pendant


Wrist watch

TxRx

(d)

Figure 7 Continued


Prop

agat

ion

loss

(dB)

30

40

50

60

70

80

90

100

110

120



Frequency (MHz)5 10 15 20 25 30 35 40 45 50 6055


(e)


TxRx

TxRx

1

2Steelcabin

GroundGround-

Ground-plane


Ground-plane




Alumini

um ta

ble

Alumini

um to

p

Woo

den t

able

Woo

den to

p




25 cm

Free space with and

plane

plane

(f)











Comparisonbetween


propagation loss























x

y

z

minus203

minus328

minus453

minus578

minus703

minus828

minus100

0

(dB)



261

cm261

cm

261

cm261

cm

261

cm261

cm305 cm 305 cm 305 cm

305 cm 305 cm 305 cm








5 Conclusion






References

































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










(d) Str4

(c) Sk-Rec

Verticalcoupler

(b) Sk-Cyl

(a)

A2

A3A4


d

X

Y

Z

8 cm

8 cm

60cm

20cm

20cm

25 cm

25cm

50

cm90

cm

15 cm45 cm


Muscle [23mm]

Bone [60mm]







Frequency (MHz)

0

05

1

15

2

25

5 10 15 20 25 30 35 40 45 50 6055



|Var

iatio

n in

pro

paga

tion

loss|(

dB)

(a)

0

2

4

6

8

10

12

14

16

18

20

Frequency (MHz)5 10 15 20 25 30 35 40 45 50 6055



|Var

iatio

n in

pro

paga

tion

loss|

(dB)

(b)










Prop

agat

ion

loss

(dB)

40

45

50

55

60

65

70

Frequency (MHz)5 10 15 20 25 30 35 40 45 50 6055





(a)

Prop

agat

ion

loss

(dB)

20

30

40

50

60

70

80


Frequency (MHz)5 10 15 20 25 30 35 40 45 50 6055

(b)















Prop

agat

ion

loss

(dB)

55

60

65

70

75

80

85

90

Frequency (MHz)5 10 15 20 25 30 35 40 45 50 6055







Prop

agat

ion

loss

(dB)

30

40

50

60

70

80

90

100

110

120



Frequency (MHz)5 10 15 20 25 30 35 40 45 50 55

(a)








(b)

Prop

agat

ion

loss

(dB)

30

40

50

60

70

80

90

100

110

120


Frequency (MHz)5 10 15 20 25 30 35 40 45 50 55


(c)




Square pendant


Rectangle pendant


Wrist watch

TxRx

(d)

Figure 7 Continued


Prop

agat

ion

loss

(dB)

30

40

50

60

70

80

90

100

110

120



Frequency (MHz)5 10 15 20 25 30 35 40 45 50 6055


(e)


TxRx

TxRx

1

2Steelcabin

GroundGround-

Ground-plane


Ground-plane




Alumini

um ta

ble

Alumini

um to

p

Woo

den t

able

Woo

den to

p




25 cm

Free space with and

plane

plane

(f)











Comparisonbetween


propagation loss























x

y

z

minus203

minus328

minus453

minus578

minus703

minus828

minus100

0

(dB)



261

cm261

cm

261

cm261

cm

261

cm261

cm305 cm 305 cm 305 cm

305 cm 305 cm 305 cm








5 Conclusion






References

































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










Frequency (MHz)

0

05

1

15

2

25

5 10 15 20 25 30 35 40 45 50 6055



|Var

iatio

n in

pro

paga

tion

loss|(

dB)

(a)

0

2

4

6

8

10

12

14

16

18

20

Frequency (MHz)5 10 15 20 25 30 35 40 45 50 6055



|Var

iatio

n in

pro

paga

tion

loss|

(dB)

(b)










Prop

agat

ion

loss

(dB)

40

45

50

55

60

65

70

Frequency (MHz)5 10 15 20 25 30 35 40 45 50 6055





(a)

Prop

agat

ion

loss

(dB)

20

30

40

50

60

70

80


Frequency (MHz)5 10 15 20 25 30 35 40 45 50 6055

(b)















Prop

agat

ion

loss

(dB)

55

60

65

70

75

80

85

90

Frequency (MHz)5 10 15 20 25 30 35 40 45 50 6055







Prop

agat

ion

loss

(dB)

30

40

50

60

70

80

90

100

110

120



Frequency (MHz)5 10 15 20 25 30 35 40 45 50 55

(a)








(b)

Prop

agat

ion

loss

(dB)

30

40

50

60

70

80

90

100

110

120


Frequency (MHz)5 10 15 20 25 30 35 40 45 50 55


(c)




Square pendant


Rectangle pendant


Wrist watch

TxRx

(d)

Figure 7 Continued


Prop

agat

ion

loss

(dB)

30

40

50

60

70

80

90

100

110

120



Frequency (MHz)5 10 15 20 25 30 35 40 45 50 6055


(e)


TxRx

TxRx

1

2Steelcabin

GroundGround-

Ground-plane


Ground-plane




Alumini

um ta

ble

Alumini

um to

p

Woo

den t

able

Woo

den to

p




25 cm

Free space with and

plane

plane

(f)











Comparisonbetween


propagation loss























x

y

z

minus203

minus328

minus453

minus578

minus703

minus828

minus100

0

(dB)



261

cm261

cm

261

cm261

cm

261

cm261

cm305 cm 305 cm 305 cm

305 cm 305 cm 305 cm








5 Conclusion






References

































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










Prop

agat

ion

loss

(dB)

40

45

50

55

60

65

70

Frequency (MHz)5 10 15 20 25 30 35 40 45 50 6055





(a)

Prop

agat

ion

loss

(dB)

20

30

40

50

60

70

80


Frequency (MHz)5 10 15 20 25 30 35 40 45 50 6055

(b)















Prop

agat

ion

loss

(dB)

55

60

65

70

75

80

85

90

Frequency (MHz)5 10 15 20 25 30 35 40 45 50 6055







Prop

agat

ion

loss

(dB)

30

40

50

60

70

80

90

100

110

120



Frequency (MHz)5 10 15 20 25 30 35 40 45 50 55

(a)








(b)

Prop

agat

ion

loss

(dB)

30

40

50

60

70

80

90

100

110

120


Frequency (MHz)5 10 15 20 25 30 35 40 45 50 55


(c)




Square pendant


Rectangle pendant


Wrist watch

TxRx

(d)

Figure 7 Continued


Prop

agat

ion

loss

(dB)

30

40

50

60

70

80

90

100

110

120



Frequency (MHz)5 10 15 20 25 30 35 40 45 50 6055


(e)


TxRx

TxRx

1

2Steelcabin

GroundGround-

Ground-plane


Ground-plane




Alumini

um ta

ble

Alumini

um to

p

Woo

den t

able

Woo

den to

p




25 cm

Free space with and

plane

plane

(f)











Comparisonbetween


propagation loss























x

y

z

minus203

minus328

minus453

minus578

minus703

minus828

minus100

0

(dB)



261

cm261

cm

261

cm261

cm

261

cm261

cm305 cm 305 cm 305 cm

305 cm 305 cm 305 cm








5 Conclusion






References

































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation



















Prop

agat

ion

loss

(dB)

55

60

65

70

75

80

85

90

Frequency (MHz)5 10 15 20 25 30 35 40 45 50 6055







Prop

agat

ion

loss

(dB)

30

40

50

60

70

80

90

100

110

120



Frequency (MHz)5 10 15 20 25 30 35 40 45 50 55

(a)








(b)

Prop

agat

ion

loss

(dB)

30

40

50

60

70

80

90

100

110

120


Frequency (MHz)5 10 15 20 25 30 35 40 45 50 55


(c)




Square pendant


Rectangle pendant


Wrist watch

TxRx

(d)

Figure 7 Continued


Prop

agat

ion

loss

(dB)

30

40

50

60

70

80

90

100

110

120



Frequency (MHz)5 10 15 20 25 30 35 40 45 50 6055


(e)


TxRx

TxRx

1

2Steelcabin

GroundGround-

Ground-plane


Ground-plane




Alumini

um ta

ble

Alumini

um to

p

Woo

den t

able

Woo

den to

p




25 cm

Free space with and

plane

plane

(f)











Comparisonbetween


propagation loss























x

y

z

minus203

minus328

minus453

minus578

minus703

minus828

minus100

0

(dB)



261

cm261

cm

261

cm261

cm

261

cm261

cm305 cm 305 cm 305 cm

305 cm 305 cm 305 cm








5 Conclusion






References

































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










Prop

agat

ion

loss

(dB)

30

40

50

60

70

80

90

100

110

120



Frequency (MHz)5 10 15 20 25 30 35 40 45 50 55

(a)








(b)

Prop

agat

ion

loss

(dB)

30

40

50

60

70

80

90

100

110

120


Frequency (MHz)5 10 15 20 25 30 35 40 45 50 55


(c)




Square pendant


Rectangle pendant


Wrist watch

TxRx

(d)

Figure 7 Continued


Prop

agat

ion

loss

(dB)

30

40

50

60

70

80

90

100

110

120



Frequency (MHz)5 10 15 20 25 30 35 40 45 50 6055


(e)


TxRx

TxRx

1

2Steelcabin

GroundGround-

Ground-plane


Ground-plane




Alumini

um ta

ble

Alumini

um to

p

Woo

den t

able

Woo

den to

p




25 cm

Free space with and

plane

plane

(f)











Comparisonbetween


propagation loss























x

y

z

minus203

minus328

minus453

minus578

minus703

minus828

minus100

0

(dB)



261

cm261

cm

261

cm261

cm

261

cm261

cm305 cm 305 cm 305 cm

305 cm 305 cm 305 cm








5 Conclusion






References

































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










Prop

agat

ion

loss

(dB)

30

40

50

60

70

80

90

100

110

120



Frequency (MHz)5 10 15 20 25 30 35 40 45 50 6055


(e)


TxRx

TxRx

1

2Steelcabin

GroundGround-

Ground-plane


Ground-plane




Alumini

um ta

ble

Alumini

um to

p

Woo

den t

able

Woo

den to

p




25 cm

Free space with and

plane

plane

(f)











Comparisonbetween


propagation loss























x

y

z

minus203

minus328

minus453

minus578

minus703

minus828

minus100

0

(dB)



261

cm261

cm

261

cm261

cm

261

cm261

cm305 cm 305 cm 305 cm

305 cm 305 cm 305 cm








5 Conclusion






References

































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation













Comparisonbetween


propagation loss























x

y

z

minus203

minus328

minus453

minus578

minus703

minus828

minus100

0

(dB)



261

cm261

cm

261

cm261

cm

261

cm261

cm305 cm 305 cm 305 cm

305 cm 305 cm 305 cm








5 Conclusion






References

































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










x

y

z

minus203

minus328

minus453

minus578

minus703

minus828

minus100

0

(dB)



261

cm261

cm

261

cm261

cm

261

cm261

cm305 cm 305 cm 305 cm

305 cm 305 cm 305 cm








5 Conclusion






References

































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation













References

































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation














RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation









research article an efficient full-wave...

Documents