triband operation enhancement based on multimode analytics

Research ArticleTriband Operation Enhancement Based on MultimodeAnalytics of Modified Rhombic Ring Structure with FractalRing Parasitic

Chatree Mahatthanajatuphat Thanakarn Suangun Norakamon Wongsin and Prayoot Akkaraekthalin

Department of Electrical and Computer Engineering King Mongkutrsquos University of Technology North BangkokBangkok 10800 ailand

Correspondence should be addressed to Prayoot Akkaraekthalin prayootaengkmutnbacth

Received 19 April 2019 Revised 14 July 2019 Accepted 4 September 2019 Published 17 October 2019

Academic Editor Symeon Nikolaou

Copyright copy 2019 Chatree Mahatthanajatuphat et al )is is an open access article distributed under the Creative CommonsAttribution License which permits unrestricted use distribution and reproduction in anymedium provided the original work isproperly cited

)is paper presents a triband operation enhancement based on multimode analytics of a monopole antenna designed bycombining a rhombic ring radiator with a strip on a top layer and a fractal ring resonator placed at the bottom layer )eproposed antenna can achieve triband operation to support the modern wireless communication systems )e antenna size isapproximately 36 times 52mm2 which is quite compacted compared with the revised antenna )e simulation and measurementresults are in good agreement )e antenna covers the operating bands at 2222 98 and 3127 at the resonant fre-quencies of 18 GHz 245 GHz and 371 GHz respectively to support the application bands of LTE 1800 WLANIEEE80211bg WiMAX and IMT Advanced Systems (5G) )e average gain of the antenna is about 2 dBi Also the radiationpatterns are omnidirectional for all operating frequencies

1 Introduction

Rapid growth of wireless data communication is the mainreason for consumer Internet access demand Recently mostpeople do not have only one wireless mobile device accessingthe Internet To save costs and battery energy for the Internetconnection mobile hotspot [1] is a solution allowing manywireless devices to connect to it Since multiple frequencyoperation is the main function of the mobile hotspot amultiband antenna as an important part of a front-endmobile hotspot should be desirable

)e literature review shows that multiband antennas canbe categorized into two types wideband antennas with notchfrequency [2ndash7] and multiband antennas with multipleresonators [8ndash14] In [2] the wideband antenna with notchfrequency composed of a swallowtail patch trapezoidground and three split ring resonators was proposed )etriple band notch was generated by the three split ringresonators placed on the radiation patch Also a capacitance

compensation was added at the backside of the patch toimprove impedance bandwidth In [3] a dual-band antennahas been created using a novel planar printed dipole )eantenna consists of a bow-tie patch and a semicircular loopoperating as electric and magnetic dipoles respectively Apair of capacitive-loaded loop slots was etched on the bow-tie patch to introduce a notched band performing the dual-band operation A wideband antenna with multiple notcheswas proposed in [4] )e antenna was designed as a circularpatch that works like a radiator and the systematic defectionslots in coplanar ground obtaining multiple notch fre-quencies Also a wideband antenna with a notch using aquarter wavelength strip has been proposed in [5] )eantenna radiator was etched by a milling machine to createthe strip acting as a nonradiating load at the suppressionfrequency resulting in a notched frequency occurrence In[6] a wideband slot antenna with dual notched frequencyhas been proposed It consists of two pairs of narrow slits inthe ground plane for the dual-band frequency rejection A

HindawiInternational Journal of Antennas and PropagationVolume 2019 Article ID 5270206 10 pageshttpsdoiorg10115520195270206

wideband antenna based on a rectangular stepped slot hasbeen proposed in [7] Two C-shaped resonators were placedadjacent to the transmission line to produce a notch fre-quency)e disadvantage of the antennas in [2ndash7] is that theoperating frequency bands could not be independentlycontrolled and the antenna radiation patterns were unusualdue to the higher-order radiating modes of the antenna

)en a multiband monopole antenna with two invertedL slots has been proposed to achieve triple operating fre-quency bands in [8] )e antenna was fed by a coplanarwaveguide (CPW) )e substrate rectangles were cut off attwo corners to improve impedance bandwidth andmatching However it did not cover the global frequencyband of WiMAX applications Also a novel multibandantenna using a Kapton polyimide flexible substrate fed by aCPW has been proposed in [9] )e antenna includesmultitriangular radiators and a circular-shaped groundplane resulting in the multiple resonance frequenciesdepending on each radiatorrsquos triangular height )e disad-vantage of this antenna is the difficulty to obtain a high-quality antenna because the conductor created by inkjet-printing is of anisotropic material In [10] a penta-band slotdipole antenna has been proposed)e antenna is created byetching the comb-like slots on metal sheets Each slot canindependently control a resonant frequency of the antennahowever the antenna has a large dimension Also a bow-tiemonopole antenna was proposed in [11] )e antenna isconstructed by etching slots of different lengths in a bow-tieto achieve the multiband operation In [12] a dual-bandmonopole antenna has been proposed )e dual-band op-eration is generated by a monopole radiator and embeddedslots with rectangular patches In [11 12] the resonantfrequencies could be independently controlled but theantenna dimensions are still large Likewise a multibandantenna with an L-shaped parasitic strip has been proposedin [13])e antenna comprises of a planar inverted L-shapedradiator and an L-shaped parasitic strip )e first and thirdresonant frequencies were generated by the radiator as theplacing of the parasitic strip on the radiatorrsquos back creates thesecond resonant frequency and improves the impedancebandwidth of the antenna However the radiation patternsof the antenna are distorted due to the asymmetricalstructure of the antenna In [14] a monopole antenna hasbeen modified to a fork-shaped structure producing dual-frequency bands By adding an L-shaped parasitic strip onthe opposite substrate layer the antenna achieves triplefrequency bands and improved impedance matchingHowever antenna production is very complicated because ithas more than one parasitic strip on the bottom layer of theantenna It can be concluded that the multiband antennaswith multiple resonators in [8ndash14] can independentlycontrol the resonant frequencies which is usually caused bythe patterns radiated by the fundamental mode of theantenna

In this paper a rhombic ring monopole antenna with stripand a ring resonator in [15] is modified and presented togenerate the operating frequency bands of LTE 1800 (LongTerm Evolution) 1710ndash1880MHz WLAN IEEE80211bg(Wireless Local Area Network) 2400ndash2484MHz WiMAX

(Worldwide Interoperability for Microwave Access) 33ndash38GHz and IMT Advanced Systems (5G) 33ndash42GHzEspecially the ring resonator is modified by applying the Kochfractal model resulting in the physical length reduction asreviewed in [16ndash19] Fractal geometry has been proven to beuseful to design an antenna such as multiband and achieveminiaturization Also the presented antenna will be developedand enhanced with triband operations based on the multi-mode analytics in a limited dimension supporting the requiredoperating frequency bands )e parameter values of thepresented antenna were determined and optimized by usingthe CSTsoftware )e function of a prototype of the presentedantenna has been confirmed by measurement )e organi-zation of this paper is the following In Section 2 the design ofthe presented antenna is given and described in detail )efunction of the antenna is verified by multimode and surfacecurrent distribution analysis Simulation and experiment re-sults of the antenna will be analyzed in Section 3 Finally theconclusions of the presented antenna are discussed in Section4

2 Antenna Design

Figure 1(a) shows the configuration of the antenna presentedin this paper It is designed on an FR-4 substrate with arelative permittivity (εr) of 42 thickness (h) of 16mm andloss tangent (tan δ) of 0019 )e proposed antenna com-poses of a rhombic ring radiator a strip and a fractal ringresonator Typically the rhombic ring radiator on the toplayer is created to support the 18GHz frequency band Toradiate the electromagnetic wave at the frequency band of35GHz the rhombic ring radiator is modified by adding astrip monopole antenna inside the radiator Moreover afractal ring resonator which is created by generating the firstiteration of the Koch fractal model [20] Figure 1(b) on allsides of a rectangular ring resonator is placed near theposition of the strip on the bottom layer for resonating thefrequency at 245GHz and improving the impedancebandwidth at 35GHz As shown in Figure 1(a) the pro-posed antenna is fed by the 50Ωmicrostrip line (Wt 3mm)with SMA connector )e optimal parameter values fordesigning the proposed antenna are summarized in Table 1

21 Mode Analysis Typically a rhombic ring monopoleantenna can be created simply as shown in Figure 2(a) )elength of the monopole antenna is designed on the fun-damental resonant frequency at 18GHz which can be es-timated with a quarter effective wavelengths by

f18GHz 3 times 108

4035 εr + 1( 1113857

1113969middot

2

radicmiddot Lr( 1113857

(1)

where Lr is the length of each side of the rhombic ring As theantenna is excited by the 50Ω microstrip line it generatesdual modes and dual-frequency resonances as illustrated bythe reflection coefficients in Figure 2(b))e results show theresonant frequencies at 188GHz and 44GHz which are thefirst and third resonant modes of the rhombic ring re-spectively Figures 2(c) and 2(d) depict the surface current

2 International Journal of Antennas and Propagation

distributions on the rhombic ring at the resonant fre-quencies of 188GHz and 44GHz As the surface currentdistributions ow along the rhombic ring it has been seenthat one null node exists at 188GHz and three null nodesoccurred at 44 GHz resulting in the rhombic ring reso-nating at the rst and third modes respectively Also therhombic ring operates at the odd mode being the radiatingmode while the even mode of the rhombic ring is thenonradiating mode Since the frequency band of 44GHzcannot cover the application requirement of IMT AdvancedSystems (5G) 33ndash42GHz the antenna was redesigned byadding a strip inside the rhombic ring to resonate at 35GHzto cover the application requirements

Before adding the strip inside the rhombic ring themechanism of the strip must be veried bymode analysis Asshown in Figure 3(a) a strip monopole antenna with aquarter eective wavelength resonating at the frequency of35GHz can be calculated by

f35GHz 3 times 108

4035 εr + 1( )radic

middot LS( ) (2)

where Ls is the length of strip line As the antenna wasexcited the antenna resonated at 38 GHz as depicted by thereection coecient in Figure 3(b) e current distributionat 38GHz is shown in Figure 3(c) It was found that no nullnode exists on the antenna us the radiating mode of the

strip is the rst mode or odd mode at 38 GHz while the evenmode is the nonradiating mode

When the strip added within the rhombic ring is excitedby the feed line as shown in Figure 4(a) resonances occur at18GHz and 39GHz Especially the resonant frequency of18GHz is generated by the rst resonant mode of therhombic ring while the resonant frequency 39GHz iscreated by combining the third resonant mode of therhombic ring and the rst resonant mode of the stripresulting from the coupling eect between the rhombic ringand the strip Also the rhombic ring monopole with stripcan cover the operating frequency bands of the LTE 1800WiMAX and IMT Advanced Systems (5G) To improve thefrequency band of the rhombic ring monopole antenna withstrip and add support of WLAN a resonator operating at245GHz should be added on the backside of the antennae length of a fractal ring resonator operating at 245GHzcan be approximated by

f245GHz 3 times 108

035 εr + 1( )radic

middot 23 middot Wk + Lk( ) middot (2 + sec θ)[ ]

(3)

whereWk and Lk are the lengths of the fractal ring resonatore mechanism of a fractal ring resonator has been in-vestigated in Figure 5 When the conguration of the fractalring resonator is excited independently as shown inFigure 5(a) it generates the rst resonant frequency of3GHz as depicted in Figure 5(b) Current distribution alongthe resonator at 3GHz is shown in Figure 5(c) reveals thatthere are two null nodes in it resulting in the resonatorradiating in the second mode or even mode Accordinglythe electrical length of the antenna is about λg As shown inFigure 6 the antenna resonates at 18GHz 245GHz324GHz and 404GHz supporting the frequency bands of165ndash196GHz 236ndash256GHz and 31ndash42GHz re-spectively at |S11| levellt minus 10 dB Particularly the resonantof 324GHz and 404GHz occurred by splitting o betweenthe rst and third modes of the strip and the rhombic ringradiator at the previous resonant frequency of 39GHzrespectively due to the coupling eect between the fractalring resonator and the rhombic ring with the strip

Top layer

W1

Wt h

Y

Z Xϕ

LS

LL r

W2

Wk

WgLt

Lk

Lg

Bottom layer

(a)

A

θ

A3

A3

A6

A6

(b)

Figure 1 (a) e conguration of the proposed antenna and (b) the initial generator model of the Koch fractal

Table 1 e presented antenna parameters

Parameter Valueθ 5103degLg 22mmLk 15mmLr 2121mmLs 15mmLt 75mmh 16mmW1 2mmW2 2mmWg 36mmWk 26mmWt 3mm

International Journal of Antennas and Propagation 3

To study the effect of the geometric parameters of theproposed antenna the parameters of Lr Wk and Ls areinvestigated further )e effect of a varying parameter Lr on

the reflection coefficient of the antenna is shown inFigure 7(a) It can be noticed that the resonant frequencies of18GHz and 404GHz shift to a lower frequency as the Lr

(a)

5

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

IS11

I (dB

)

4 5

0

(b)

Am (log)384

191

949

468

227

107

0473

0173

0

(c)

Am (log)384

191

949

468

227

107

0473

0173

0

(d)

Figure 2 Mode analysis of the rhombic ring (a) Configuration of the rhombic ring (b) Reflection coefficients (c) Current distribution at188GHz (d) Current distribution at 404GHz

(a)

5

0

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

IS11

I (dB

)

4 5

(b)

Am (log)24

132

721

391

208

107

051

02

0

(c)

Figure 3 Mode analysis on the strip (a) Configuration of the strip (b) Reflection coefficients (c) Current distribution at 38 GHz


parameters increase which is caused by the extendedelectrical length of the rhombic ring monopole antennaaccording to the rst and third radiating modes of therhombic ring antenna Nevertheless the impedancematching of the antenna is degenerated at 324GHz due tothe coupling eect between the rhombic ring and the stripline

e frequency responses of the antenna with an in-creasing parameter Wk are depicted in Figure 7(b) It hasbeen seen that the frequency of 245GHz shifts to a lowerfrequency due to the expanded electrical length of the fractalring resonator while the impedance bandwidth andmatching at the third frequency band is changed because theextending length of the resonator disturbs the coupling eectbetween the rhombic ring and strip As shown in Figure 7(c)when varying the parameter Ls the resonant frequency of324GHz is shifted to a lower frequency resulting from theincrease of the electrical length of the strip However the

(a)

5

0

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

IS11

I (dB

)

4 5

(b)

Figure 4 (a) Conguration of the rhombic ring with strip and (b) reection coecients

(a)

5

0

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

IS11

I (dB

)

4 5

(b)

Am (log)394

193

94

455

218

101

0439

0159

0

(c)

Figure 5 Mode analysis of the Koch fractal ring resonator (a) Conguration of the Koch fractal ring resonator (b) Reection coecients(c) Current distribution at 3GHz

5

0

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

IS11

I (dB

)

4 5

Figure 6 e reection coecient of the rhombic ring with stripand Koch fractal ring resonator


parameters of Lr Wk and Ls can be optimized by thesimulation software for improving the impedance band-width and matching of the presented antenna en thesurface current distributions of the optimized antenna willbe shown and discussed in detail further on

22 Surface Current Distribution To investigate the mech-anism of the proposed antenna the surface current distri-butions on the rhombic ring radiator strip and the fractalring resonator are discussed As mentioned in the previoussubsection the proposed antenna can achieve multipleresonant frequencies of 18GHz 245GHz 324 and404GHz erefore various surface current distributionsbased on the resonant frequencies of reection coecients

on the antenna are carried out by the simulation softwareFigure 8(a) shows the surface current distribution on theproposed antenna at 18GHz Since the height of therhombic ring radiator is approximately at quarter eectivewavelength (028λg) the major current distribution occurson the edge of the rhombic ring radiator It has been in-dicated that the current ows up to the highest position ofthe rhombic ring radiator and has a null node on itMeanwhile the current distributions on the strip and thefractal ring resonator are minor en it can be neglectbecause the rst radiating mode of the strip is not at thefrequency of 18GHz and also the fractal ring resonatorcannot radiate the electromagnetic wave in the rst modeConsequently the rhombic ring radiator can radiate thewave at 18GHz independently and does not disturb the

5

0

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

Lr = 198 mmLr = 2121 mmLr = 2262 mm

IS11

I (dB

)

4 5

(a)

Wk = 22mmWk = 24mmWk = 26mm

5

0

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

IS11

I (dB

)

4 5

(b)

Ls = 155mmLs = 16mmLs = 165mm

5

0

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

IS11

I (dB

)

4 5

(c)

Figure 7 Simulated reection coecients with varying the parameters of (a) Lr (b) Wk and (c) Ls


nonradiating mode of the strip and the fractal ringresonator

At the frequency of 245GHz the surface current dis-tribution is studied as shown in Figure 8(b) It has beenshown that major current distributions exist on the strip andthe fractal ring resonator while the current distribution onthe rhombic ring radiator is neglectable As a result it hasbeen seen that the rhombic ring radiator cannot propagatethe electromagnetic wave due to the radiator working in astate of nonradiating mode at this frequency Although themajor current passes along on the strip it cannot propagatethe wave because the first radiating mode of the strip is not atthis frequency )erefore the strip acts as feed line couplingthe electromagnetic field to the fractal ring resonator )enthe fractal ring resonator is excited by the feed strip andmainly propagates the electromagnetic wave in a state ofradiating mode at 245GHz Also the resonator has two nullnodes due to its resonance at the second mode and theelectrical wavelength on the fractal ring resonator is about115λg according to the major current distribution on it

)e current distribution at 324GHz is depicted inFigure 8(c) )e result reveals a minor current flow throughthe rhombic ring radiator and the fractal ring resonatorwhile the major current exists on the strip As a result therhombic ring and fractal ring resonator behave as a load to

improve impedance matching and bandwidth when in astate of nonradiating mode at 324GHz Conversely thestrip operates at the radiating mode at 324GHz and there isno null node on the strip As a result the strip operates in thefirst mode Moreover the electrical wavelength on the stripis approximately 025λg corresponding to the major currentdistribution on it

As illustrated in Figure 8(d) at 404GHz it can be foundthat the major current distribution appears on the rhombicring radiator with three null nodes and minor currentdistributions exist on the strip and the fractal ring resonator)e rhombic ring operating in the third radiating mode isthe main radiator to propagate the electromagnetic wave at404GHz Hence the strip and the fractal resonator per-forming in the state of nonradiating mode cannot propagatethe wave

As verified by the surface current distribution analysis onthe proposed antenna it can be concluded that the antennasupports multiple resonant frequencies with the multimodeAt the first resonant frequency the rhombic ring radiatoroperates in the odd radiating mode (the first mode) Alsothe fractal ring resonator radiates in the even radiating mode(the second mode) at the second resonant frequency )ethird resonant frequency is created next by the first mode ofthe strip Finally the fourth resonant frequency is generated

Am (log)456

236

122

625

315

154

07

0264

0

(a)

Am (log)329

184

103

569

309

161

0782

0312

0

(b)

Am (log)423

245

141

807

451

242

121

0492

0

(c)

Am (log)517

301

174

996

558

301

15

0613

0

(d)

Figure 8 Surface current distribution on the top and bottom layer of the presented antenna at the operating frequencies of (a) 18 GHz(b) 245GHz (c) 324GHz and (d) 404GHz


by the third mode of the rhombic ring radiator which is theodd radiating mode

3 Simulation and Experiment

eproposed antenna is then fabricated bymechanical etchingand is shown in Figure 9e optimal parameters are shown inTable 1 In the experiment the antenna reection coecientswere measured by the Rohde amp Schwarz ZVB20 VNA eresults shown in Figures 6 and 10 indicate that the operatingfrequency bands and impedance matching are depended onthe electromagnetic coupling eect between the rhombic ringwith strip and the Koch fractal ring resonator Also thesimulated and measured results of antenna agree well How-ever the simulated and measured results are slightly dierentin the third operating frequency band due to a faulty placementof the rhombic ring radiator on the top layer and the Kochfractal ring resonator on the bottom layer of the antenna

e simulated and measured gains are illustrated inFigure 11 In the rst operating frequency band the averagemeasured gain is approximately 2 dBi and about 25 dBi in the

second and third operating frequency band While themaximum gain of 435 dBi is approached at the higher fre-quency band of 4GHz it has been found that the maximumgain is produced by combining the electromagnetic eldsbetween the third mode of the rhombic ring radiator and therst mode of the strip A good agreement of antenna gain isachieved between the simulated and measured results

e antenna patterns were measured in an anechoicchamber Figures 12(a) and 12(b) show the simulated andmeasured radiation patterns in the X-Z plane and Y-Z planeat the operating frequencies of 18GHz 245GHz 324GHzand 404GHz respectively e radiation patterns of theproposed antenna are omnidirectional at all operating fre-quencies as illustrated in Figure 12 It can be noticed that themagnitudes of cross-polarization in X-Z and Y-Z planes arebelow minus 18 dB Also the peak gains of the antenna areexhibited at 0 and 180 degrees at the frequencies of 18GHz245GHz and 324GHz However at 404GHz the peakgains of the antenna exist at 15 and 165 degrees due to theantenna operating at the third radiating mode

4 Conclusions

A triple-band enhancement based on multimode analyticswith strip and Koch fractal ring resonator has been proposedand compared with other antennas as shown in Table 2 eimpedance bandwidth and dimension can be improved bythe electromagnetic coupling eect among the rhombic ringradiator with strip and the Koch fractal ring resonator tocover the three operation frequency bands for applicationsin LTE 1800 (Long Term Evolution) 171ndash188GHz WLANIEEE80211bg (Wireless Local Area Network) 24ndash2484GHz WiMAX (Worldwide Interoperability for Mi-crowave Access) 33ndash38 GHz and IMT Advanced Systems(5G) 34ndash42GHz e investigation revealed that the rstband is produced by the rst mode of the rhombic ring

Figure 9 A prototype of the presented antenna

5

0

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

IS11

I (dB

)

4 5

Simulated resultMeasured result

Figure 10 Simulated and measured |S11| of the presented antenna

5

0

ndash5

ndash10

ndash15

ndash201 2 3

Frequency (GHz)

Gai

n (d

Bi)

4 5


Figure 11 Simulated and measured gains at ϕ 0 degrees in the X-Z plane of the presented antenna


radiator and the second band is generated by the secondmode of the Koch fractal ring resonator while the third bandis created by the rst mode of the strip together with thethird mode of the rhombic ring radiator Furthermore theaverage gains of the proposed antenna are approximately2 dBi at the rst band and 25 dBi at the second and thirdbands It has been shown that the radiation patterns arequasi-omnidirectional at all operating frequency bandswhile a low cross-polarization is obtained

Data Availability

e experimental data used to support the ndings of thisstudy are available from the corresponding author uponrequest

Conflicts of Interest

e authors declare that there are no conicts of interest

Acknowledgments

e authors would like to thank theailand Research Fund(TRF) under a senior research fund (RTA6080008) for theresearch grant

References

[1] K Kirti R I Venkata and V Pallapa ldquoEnergy ecientscheduling in 4G smart phones for mobile hotspot applica-tionrdquo in Proceedings of the 2012 National Conference on

324GHz

X-Z planeSim copolarSim cross polarMeas copolarMeas cross polar

030

60

90

120

150180

210

240

270

300

3300ndash10ndash20ndash30ndash40ndash30ndash20ndash10

0

404GHz


030

60

90

120

150180

210

240

270

300


0

0 018GHz

30

60


90

120

150180

210

240

270

300


0

245GHz


030

60

90

120

150180

210

240

270

300


0

(a)

324GHz

Y-Z planeSim copolarSim cross polarMeas copolarMeas cross polar

030

60

90

120

150180

210

240

270

300


0

404GHz


030

60

90

120

150180210

240

270

300


0

18GHz


030

60

90

120

150180

210

240

270

300


0

245GHz


030

60

90

120

150180

210

240

270

300


0

(b)

Figure 12 Simulated andmeasured radiation patterns of the presented antenna at the resonant frequencies of 18 GHz 245GHz 324GHzand 404GHz in (a) X-Z planes and (b) Y-Z planes

Table 2 Comparison between the presented antenna and other designs

References impedance bandwidths (|S11| levellt minus 10 dB) Overall dimension (mm3) Radiator type

[11] 2249 (550MHz at 245GHz) 914 (320MHz at35 GHz) and 1733 (920MHz at 53 GHz) 100times 60times 08 Monopole antenna

[12] 51 (124MHz at 245GHz) and 224 (1124MHz at55GHz) 50times 30times16 Slot and monopole antenna

[21] 358 (1010MHz at 2825GHz) and 244(1380MHz at 565GHz) 693times 662times16 Monopole antenna


Proposed antenna 2222 (400MHz at 18GHz) 98 (240MHz at245GHz) and 3127 (1160MHz at 371GHz) 36times 52times16 Monopole antenna


Communications (NCC) vol 2012 p 5 Kharagpur IndiaFebruary 2012

[2] W Xiao T Mei Y Lan Y Wu R Xu and Y Xu ldquoTripleband-notched UWB monopole antenna on ultra-thin liquidcrystal polymer based on ESCSRRrdquo Electronics Letters vol 53no 2 pp 57-58 2017

[3] C-Y Shuai and G-M Wang ldquoA novel planar printed dual-band magneto-electric dipole antennardquo IEEE Access vol 5pp 10062ndash10067 2017

[4] S U Rehman and M A S Alkanhal ldquoDesign and systemcharacterization of ultra-wideband antennas with multipleband-rejectionrdquo IEEE Access vol 5 pp 17988ndash17996 2017

[5] P Moeikham C Mahatthanajatuphat and P AkkaraekthalinldquoA compact UWB antenna with a quarter-wavelength strip ina rectangular slot for 55 GHz band notchrdquo InternationalJournal of Antennas and Propagation vol 2013 Article ID574128 9 pages 2013

[6] P Moeikham and P Akkaraekthalin ldquoA compact printed slotantenna with high out-of-band rejection for WLANWiMAXapplicationsrdquo Radioengineering vol 25 no 4 pp 672ndash6792016

[7] R Kumar R Khokle and R V S R Krishna ldquoA horizontallypolarized rectangular stepped slot antenna for ultra widebandwidth with boresight radiation patternsrdquo IEEE Trans-actions on Antennas and Propagation vol 62 no 7pp 3501ndash3510 2014

[8] H Chen X Yang Y Z Yin S T Fan and J J Wu ldquoTribandplanar monopole antenna with compact radiator for WLANWiMAX applicationsrdquo IEEE Antennas and Wireless Propa-gation Letters vol 12 pp 1440ndash1443 2013

[9] S Ahmed F A Tahir A Shamim and H M Cheema ldquoAcompact Kapton-based inkjet-printed multiband antenna forflexible wireless devicesrdquo IEEE Antennas and WirelessPropagation Letters vol 14 pp 1802ndash1805 2015

[10] Y-J Chen T-W Liu and W-H Tu ldquoCPW-fed penta-bandslot dipole antenna based on comb-like metal sheetsrdquo IEEEAntennas and Wireless Propagation Letters vol 16 pp 202ndash205 2017

[11] M-T Wu and M-L Chuang ldquoMultibroadband slotted bow-tie monopole antennardquo IEEE Antennas and Wireless Propa-gation Letters vol 14 pp 887ndash890 2015

[12] C-Y Huang and E-Z Yu ldquoA slot-monopole antenna fordual-band WLAN applicationsrdquo IEEE Antennas and WirelessPropagation Letters vol 10 pp 500ndash502 2011

[13] J-H Lu and B-J Huan ldquoPlanar multi-band monopole an-tenna with L-shaped parasitic strip for WiMAX applicationrdquoElectronics Letters vol 46 no 10 pp 671-672 2010

[14] P Xu Z-H Yan and C Wang ldquoMulti-band modified fork-shaped monopole antenna with dual L-shaped parasiticplanerdquo Electronics Letters vol 47 no 6 pp 364-365 2011

[15] N Wongsin T Suangun C Mahatthanajatuphat andP Akkaraekthalin ldquoA rhombic ring monopole antenna withstripline and ring resonator for multiband operationrdquo inProceedings of the 14th International Conference on ElectricalEngineeringElectronics Computer Telecommunications andInformation Technology (ECTI-CON) pp 706ndash709 Phuket)ailand June 2017

[16] S R Best ldquoOn the resonant properties of the Koch fractal andother wire monopole antennasrdquo IEEE Antennas and WirelessPropagation Letters vol 1 pp 74ndash76 2002

[17] D D Krishna M Gopikrishna C K Aanandan P Mohananand K Vasudevan ldquoCompact wideband Koch fractal printedslot antennardquo IET Microwaves Antennas amp Propagationvol 3 no 5 pp 782ndash789 2009

[18] A Farswan A K Gautam B K Kanaujia and K RambabuldquoDesign of Koch fractal circularly polarized antenna forhandheld UHF RFID reader applicationsrdquo IEEE Transactionson Antennas and Propagation vol 64 no 2 pp 771ndash7752016

[19] H-T Hsu and T-J Huang ldquoA koch-shaped log-periodicdipole array (LPDA) antenna for universal ultra-high-fre-quency (UHF) radio frequency identification (RFID) hand-held readerrdquo IEEE Transactions on Antennas and Propagationvol 61 no 9 pp 4852ndash4856 2013

[20] D H Werner and S Gangul ldquoAn overview of fractal antennaengineering researchrdquo IEEE Antennas and PropagationMagazine vol 45 no 1 pp 38ndash57 2003

[21] W-C Liu and C-M Wu ldquoBroadband dual-frequency CPW-fed planar monopole antenna with rectangular notchrdquoElectronics Letters vol 40 no 11 p 642 2004

[22] H Huang Y Liu S Zhang and S Gong ldquoMultiband met-amaterial-loaded monopole antenna for WLANWiMAXapplicationsrdquo IEEE Antennas and Wireless Propagation Let-ters vol 14 pp 662ndash665 2015


International Journal of

AerospaceEngineeringHindawiwwwhindawicom Volume 2018

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Hindawiwwwhindawicom Volume 2018


Active and Passive Electronic Components

VLSI Design



Shock and Vibration


Civil EngineeringAdvances in

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Electrical and Computer Engineering

Journal of

Advances inOptoElectronics

Hindawiwwwhindawicom

Volume 2018

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

Control Scienceand Engineering

Journal of



Journal ofEngineeringVolume 2018

SensorsJournal of



RotatingMachinery


Modelling ampSimulationin EngineeringHindawiwwwhindawicom Volume 2018


Chemical EngineeringInternational Journal of Antennas and

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Navigation and Observation


Hindawi

wwwhindawicom Volume 2018

Advances in

Multimedia

Submit your manuscripts atwwwhindawicom

wideband antenna based on a rectangular stepped slot hasbeen proposed in [7] Two C-shaped resonators were placedadjacent to the transmission line to produce a notch fre-quency)e disadvantage of the antennas in [2ndash7] is that theoperating frequency bands could not be independentlycontrolled and the antenna radiation patterns were unusualdue to the higher-order radiating modes of the antenna

)en a multiband monopole antenna with two invertedL slots has been proposed to achieve triple operating fre-quency bands in [8] )e antenna was fed by a coplanarwaveguide (CPW) )e substrate rectangles were cut off attwo corners to improve impedance bandwidth andmatching However it did not cover the global frequencyband of WiMAX applications Also a novel multibandantenna using a Kapton polyimide flexible substrate fed by aCPW has been proposed in [9] )e antenna includesmultitriangular radiators and a circular-shaped groundplane resulting in the multiple resonance frequenciesdepending on each radiatorrsquos triangular height )e disad-vantage of this antenna is the difficulty to obtain a high-quality antenna because the conductor created by inkjet-printing is of anisotropic material In [10] a penta-band slotdipole antenna has been proposed)e antenna is created byetching the comb-like slots on metal sheets Each slot canindependently control a resonant frequency of the antennahowever the antenna has a large dimension Also a bow-tiemonopole antenna was proposed in [11] )e antenna isconstructed by etching slots of different lengths in a bow-tieto achieve the multiband operation In [12] a dual-bandmonopole antenna has been proposed )e dual-band op-eration is generated by a monopole radiator and embeddedslots with rectangular patches In [11 12] the resonantfrequencies could be independently controlled but theantenna dimensions are still large Likewise a multibandantenna with an L-shaped parasitic strip has been proposedin [13])e antenna comprises of a planar inverted L-shapedradiator and an L-shaped parasitic strip )e first and thirdresonant frequencies were generated by the radiator as theplacing of the parasitic strip on the radiatorrsquos back creates thesecond resonant frequency and improves the impedancebandwidth of the antenna However the radiation patternsof the antenna are distorted due to the asymmetricalstructure of the antenna In [14] a monopole antenna hasbeen modified to a fork-shaped structure producing dual-frequency bands By adding an L-shaped parasitic strip onthe opposite substrate layer the antenna achieves triplefrequency bands and improved impedance matchingHowever antenna production is very complicated because ithas more than one parasitic strip on the bottom layer of theantenna It can be concluded that the multiband antennaswith multiple resonators in [8ndash14] can independentlycontrol the resonant frequencies which is usually caused bythe patterns radiated by the fundamental mode of theantenna

In this paper a rhombic ring monopole antenna with stripand a ring resonator in [15] is modified and presented togenerate the operating frequency bands of LTE 1800 (LongTerm Evolution) 1710ndash1880MHz WLAN IEEE80211bg(Wireless Local Area Network) 2400ndash2484MHz WiMAX

(Worldwide Interoperability for Microwave Access) 33ndash38GHz and IMT Advanced Systems (5G) 33ndash42GHzEspecially the ring resonator is modified by applying the Kochfractal model resulting in the physical length reduction asreviewed in [16ndash19] Fractal geometry has been proven to beuseful to design an antenna such as multiband and achieveminiaturization Also the presented antenna will be developedand enhanced with triband operations based on the multi-mode analytics in a limited dimension supporting the requiredoperating frequency bands )e parameter values of thepresented antenna were determined and optimized by usingthe CSTsoftware )e function of a prototype of the presentedantenna has been confirmed by measurement )e organi-zation of this paper is the following In Section 2 the design ofthe presented antenna is given and described in detail )efunction of the antenna is verified by multimode and surfacecurrent distribution analysis Simulation and experiment re-sults of the antenna will be analyzed in Section 3 Finally theconclusions of the presented antenna are discussed in Section4

2 Antenna Design

Figure 1(a) shows the configuration of the antenna presentedin this paper It is designed on an FR-4 substrate with arelative permittivity (εr) of 42 thickness (h) of 16mm andloss tangent (tan δ) of 0019 )e proposed antenna com-poses of a rhombic ring radiator a strip and a fractal ringresonator Typically the rhombic ring radiator on the toplayer is created to support the 18GHz frequency band Toradiate the electromagnetic wave at the frequency band of35GHz the rhombic ring radiator is modified by adding astrip monopole antenna inside the radiator Moreover afractal ring resonator which is created by generating the firstiteration of the Koch fractal model [20] Figure 1(b) on allsides of a rectangular ring resonator is placed near theposition of the strip on the bottom layer for resonating thefrequency at 245GHz and improving the impedancebandwidth at 35GHz As shown in Figure 1(a) the pro-posed antenna is fed by the 50Ωmicrostrip line (Wt 3mm)with SMA connector )e optimal parameter values fordesigning the proposed antenna are summarized in Table 1

21 Mode Analysis Typically a rhombic ring monopoleantenna can be created simply as shown in Figure 2(a) )elength of the monopole antenna is designed on the fun-damental resonant frequency at 18GHz which can be es-timated with a quarter effective wavelengths by

f18GHz 3 times 108

4035 εr + 1( 1113857

1113969middot

2

radicmiddot Lr( 1113857

(1)

where Lr is the length of each side of the rhombic ring As theantenna is excited by the 50Ω microstrip line it generatesdual modes and dual-frequency resonances as illustrated bythe reflection coefficients in Figure 2(b))e results show theresonant frequencies at 188GHz and 44GHz which are thefirst and third resonant modes of the rhombic ring re-spectively Figures 2(c) and 2(d) depict the surface current




f35GHz 3 times 108

4035 εr + 1( )radic

middot LS( ) (2)




f245GHz 3 times 108

035 εr + 1( )radic


(3)


Top layer

W1

Wt h

Y

Z Xϕ

LS

LL r

W2

Wk

WgLt

Lk

Lg

Bottom layer

(a)

A

θ

A3

A3

A6

A6

(b)







(a)

5

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

IS11

I (dB

)

4 5

0

(b)

Am (log)384

191

949

468

227

107

0473

0173

0

(c)

Am (log)384

191

949

468

227

107

0473

0173

0

(d)


(a)

5

0

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

IS11

I (dB

)

4 5

(b)

Am (log)24

132

721

391

208

107

051

02

0

(c)





(a)

5

0

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

IS11

I (dB

)

4 5

(b)


(a)

5

0

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

IS11

I (dB

)

4 5

(b)

Am (log)394

193

94

455

218

101

0439

0159

0

(c)


5

0

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

IS11

I (dB

)

4 5






5

0

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

Lr = 198 mmLr = 2121 mmLr = 2262 mm

IS11

I (dB

)

4 5

(a)


5

0

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

IS11

I (dB

)

4 5

(b)


5

0

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

IS11

I (dB

)

4 5

(c)









Am (log)456

236

122

625

315

154

07

0264

0

(a)

Am (log)329

184

103

569

309

161

0782

0312

0

(b)

Am (log)423

245

141

807

451

242

121

0492

0

(c)

Am (log)517

301

174

996

558

301

15

0613

0

(d)









4 Conclusions



5

0

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

IS11

I (dB

)

4 5



5

0

ndash5

ndash10

ndash15

ndash201 2 3

Frequency (GHz)

Gai

n (d

Bi)

4 5





Data Availability




Acknowledgments


References


324GHz


030

60

90

120

150180

210

240

270

300


0

404GHz


030

60

90

120

150180

210

240

270

300


0

0 018GHz

30

60


90

120

150180

210

240

270

300


0

245GHz


030

60

90

120

150180

210

240

270

300


0

(a)

324GHz


030

60

90

120

150180

210

240

270

300


0

404GHz


030

60

90

120

150180210

240

270

300


0

18GHz


030

60

90

120

150180

210

240

270

300


0

245GHz


030

60

90

120

150180

210

240

270

300


0

(b)



































RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia




f35GHz 3 times 108

4035 εr + 1( )radic

middot LS( ) (2)




f245GHz 3 times 108

035 εr + 1( )radic


(3)


Top layer

W1

Wt h

Y

Z Xϕ

LS

LL r

W2

Wk

WgLt

Lk

Lg

Bottom layer

(a)

A

θ

A3

A3

A6

A6

(b)







(a)

5

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

IS11

I (dB

)

4 5

0

(b)

Am (log)384

191

949

468

227

107

0473

0173

0

(c)

Am (log)384

191

949

468

227

107

0473

0173

0

(d)


(a)

5

0

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

IS11

I (dB

)

4 5

(b)

Am (log)24

132

721

391

208

107

051

02

0

(c)





(a)

5

0

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

IS11

I (dB

)

4 5

(b)


(a)

5

0

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

IS11

I (dB

)

4 5

(b)

Am (log)394

193

94

455

218

101

0439

0159

0

(c)


5

0

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

IS11

I (dB

)

4 5






5

0

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

Lr = 198 mmLr = 2121 mmLr = 2262 mm

IS11

I (dB

)

4 5

(a)


5

0

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

IS11

I (dB

)

4 5

(b)


5

0

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

IS11

I (dB

)

4 5

(c)









Am (log)456

236

122

625

315

154

07

0264

0

(a)

Am (log)329

184

103

569

309

161

0782

0312

0

(b)

Am (log)423

245

141

807

451

242

121

0492

0

(c)

Am (log)517

301

174

996

558

301

15

0613

0

(d)









4 Conclusions



5

0

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

IS11

I (dB

)

4 5



5

0

ndash5

ndash10

ndash15

ndash201 2 3

Frequency (GHz)

Gai

n (d

Bi)

4 5





Data Availability




Acknowledgments


References


324GHz


030

60

90

120

150180

210

240

270

300


0

404GHz


030

60

90

120

150180

210

240

270

300


0

0 018GHz

30

60


90

120

150180

210

240

270

300


0

245GHz


030

60

90

120

150180

210

240

270

300


0

(a)

324GHz


030

60

90

120

150180

210

240

270

300


0

404GHz


030

60

90

120

150180210

240

270

300


0

18GHz


030

60

90

120

150180

210

240

270

300


0

245GHz


030

60

90

120

150180

210

240

270

300


0

(b)



































RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia




(a)

5

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

IS11

I (dB

)

4 5

0

(b)

Am (log)384

191

949

468

227

107

0473

0173

0

(c)

Am (log)384

191

949

468

227

107

0473

0173

0

(d)


(a)

5

0

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

IS11

I (dB

)

4 5

(b)

Am (log)24

132

721

391

208

107

051

02

0

(c)





(a)

5

0

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

IS11

I (dB

)

4 5

(b)


(a)

5

0

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

IS11

I (dB

)

4 5

(b)

Am (log)394

193

94

455

218

101

0439

0159

0

(c)


5

0

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

IS11

I (dB

)

4 5






5

0

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

Lr = 198 mmLr = 2121 mmLr = 2262 mm

IS11

I (dB

)

4 5

(a)


5

0

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

IS11

I (dB

)

4 5

(b)


5

0

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

IS11

I (dB

)

4 5

(c)









Am (log)456

236

122

625

315

154

07

0264

0

(a)

Am (log)329

184

103

569

309

161

0782

0312

0

(b)

Am (log)423

245

141

807

451

242

121

0492

0

(c)

Am (log)517

301

174

996

558

301

15

0613

0

(d)









4 Conclusions



5

0

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

IS11

I (dB

)

4 5



5

0

ndash5

ndash10

ndash15

ndash201 2 3

Frequency (GHz)

Gai

n (d

Bi)

4 5





Data Availability




Acknowledgments


References


324GHz


030

60

90

120

150180

210

240

270

300


0

404GHz


030

60

90

120

150180

210

240

270

300


0

0 018GHz

30

60


90

120

150180

210

240

270

300


0

245GHz


030

60

90

120

150180

210

240

270

300


0

(a)

324GHz


030

60

90

120

150180

210

240

270

300


0

404GHz


030

60

90

120

150180210

240

270

300


0

18GHz


030

60

90

120

150180

210

240

270

300


0

245GHz


030

60

90

120

150180

210

240

270

300


0

(b)



































RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia




(a)

5

0

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

IS11

I (dB

)

4 5

(b)


(a)

5

0

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

IS11

I (dB

)

4 5

(b)

Am (log)394

193

94

455

218

101

0439

0159

0

(c)


5

0

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

IS11

I (dB

)

4 5






5

0

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

Lr = 198 mmLr = 2121 mmLr = 2262 mm

IS11

I (dB

)

4 5

(a)


5

0

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

IS11

I (dB

)

4 5

(b)


5

0

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

IS11

I (dB

)

4 5

(c)









Am (log)456

236

122

625

315

154

07

0264

0

(a)

Am (log)329

184

103

569

309

161

0782

0312

0

(b)

Am (log)423

245

141

807

451

242

121

0492

0

(c)

Am (log)517

301

174

996

558

301

15

0613

0

(d)









4 Conclusions



5

0

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

IS11

I (dB

)

4 5



5

0

ndash5

ndash10

ndash15

ndash201 2 3

Frequency (GHz)

Gai

n (d

Bi)

4 5





Data Availability




Acknowledgments


References


324GHz


030

60

90

120

150180

210

240

270

300


0

404GHz


030

60

90

120

150180

210

240

270

300


0

0 018GHz

30

60


90

120

150180

210

240

270

300


0

245GHz


030

60

90

120

150180

210

240

270

300


0

(a)

324GHz


030

60

90

120

150180

210

240

270

300


0

404GHz


030

60

90

120

150180210

240

270

300


0

18GHz


030

60

90

120

150180

210

240

270

300


0

245GHz


030

60

90

120

150180

210

240

270

300


0

(b)



































RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia





5

0

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

Lr = 198 mmLr = 2121 mmLr = 2262 mm

IS11

I (dB

)

4 5

(a)


5

0

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

IS11

I (dB

)

4 5

(b)


5

0

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

IS11

I (dB

)

4 5

(c)









Am (log)456

236

122

625

315

154

07

0264

0

(a)

Am (log)329

184

103

569

309

161

0782

0312

0

(b)

Am (log)423

245

141

807

451

242

121

0492

0

(c)

Am (log)517

301

174

996

558

301

15

0613

0

(d)









4 Conclusions



5

0

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

IS11

I (dB

)

4 5



5

0

ndash5

ndash10

ndash15

ndash201 2 3

Frequency (GHz)

Gai

n (d

Bi)

4 5





Data Availability




Acknowledgments


References


324GHz


030

60

90

120

150180

210

240

270

300


0

404GHz


030

60

90

120

150180

210

240

270

300


0

0 018GHz

30

60


90

120

150180

210

240

270

300


0

245GHz


030

60

90

120

150180

210

240

270

300


0

(a)

324GHz


030

60

90

120

150180

210

240

270

300


0

404GHz


030

60

90

120

150180210

240

270

300


0

18GHz


030

60

90

120

150180

210

240

270

300


0

245GHz


030

60

90

120

150180

210

240

270

300


0

(b)



































RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia








Am (log)456

236

122

625

315

154

07

0264

0

(a)

Am (log)329

184

103

569

309

161

0782

0312

0

(b)

Am (log)423

245

141

807

451

242

121

0492

0

(c)

Am (log)517

301

174

996

558

301

15

0613

0

(d)









4 Conclusions



5

0

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

IS11

I (dB

)

4 5



5

0

ndash5

ndash10

ndash15

ndash201 2 3

Frequency (GHz)

Gai

n (d

Bi)

4 5





Data Availability




Acknowledgments


References


324GHz


030

60

90

120

150180

210

240

270

300


0

404GHz


030

60

90

120

150180

210

240

270

300


0

0 018GHz

30

60


90

120

150180

210

240

270

300


0

245GHz


030

60

90

120

150180

210

240

270

300


0

(a)

324GHz


030

60

90

120

150180

210

240

270

300


0

404GHz


030

60

90

120

150180210

240

270

300


0

18GHz


030

60

90

120

150180

210

240

270

300


0

245GHz


030

60

90

120

150180

210

240

270

300


0

(b)



































RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia








4 Conclusions



5

0

ndash5

ndash10

ndash15

ndash20

ndash25

ndash30

ndash35

ndash401 2 3

Frequency (GHz)

IS11

I (dB

)

4 5



5

0

ndash5

ndash10

ndash15

ndash201 2 3

Frequency (GHz)

Gai

n (d

Bi)

4 5





Data Availability




Acknowledgments


References


324GHz


030

60

90

120

150180

210

240

270

300


0

404GHz


030

60

90

120

150180

210

240

270

300


0

0 018GHz

30

60


90

120

150180

210

240

270

300


0

245GHz


030

60

90

120

150180

210

240

270

300


0

(a)

324GHz


030

60

90

120

150180

210

240

270

300


0

404GHz


030

60

90

120

150180210

240

270

300


0

18GHz


030

60

90

120

150180

210

240

270

300


0

245GHz


030

60

90

120

150180

210

240

270

300


0

(b)



































RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia



Data Availability




Acknowledgments


References


324GHz


030

60

90

120

150180

210

240

270

300


0

404GHz


030

60

90

120

150180

210

240

270

300


0

0 018GHz

30

60


90

120

150180

210

240

270

300


0

245GHz


030

60

90

120

150180

210

240

270

300


0

(a)

324GHz


030

60

90

120

150180

210

240

270

300


0

404GHz


030

60

90

120

150180210

240

270

300


0

18GHz


030

60

90

120

150180

210

240

270

300


0

245GHz


030

60

90

120

150180

210

240

270

300


0

(b)



































RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia



























RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia


triband operation enhancement based on multimode analytics

Documents