COMPACT AND HIGHLY EFFICIENT MULTIFUNCTION MICROSTRIP (PATCH) ANTENNA DESIGN

Ntawangaheza Jean de Dieu(金利 )ntajado@mail.ustc.edu.cn

(PPT1ofPPT3)

A REVIEW

OUTLINE

PEC GND Disadvantages and surface waves excitation

AMC/HIS(RIS) weaknesses and their performance enhancement.

Review of traditional reconfig. M(P)As

AMC/HIS/RIS structures in compact high performance M(P)As design.

PEC GND& ITS DISADVANTAGES

In real life, antennas are installed in close proximity to good/semi conductor materials, and they affect their performance in different ways:

.

They reflect an EM wave originating at antenna, depending on the conductor dimensions, position and its distance from the antenna, direct wave and reflected waves may form a constructive or destructive interference.

Therefore total E field strength may be larger or less than that in free space, leading to an increased/reduced antenna efficiency, respectively.

Even worse, if the nearby conductor is not perfect , there will be no reflection at all, rather a dissipation(absorption) of incident EM wave( mobile phone and user).

Perfect electric Conductor with dimensions>the operating wavelength=ground plane known as perfect electric conductor ground plane(PEC GND)

Ref: Fan Yang and Yahya Rahmat, EBG structures in antenna engineering, Cambridge university press2009 PP10,PP156. Yi Huang and Kevin Boyle, Antennas from theory to practice, Wiley 2008, PP208-210,Joseph Carr an Gearge H., practical antenna handbook 5 th, Mc Graw Hill, 2012, PP164

PEC GND& ITS DISADVANTAGES(CONT.)

Reflection/ diffraction of an EM wave from the antenna’s GND degrades considerably its performances in several ways:

.

Increased antenna back radiation( lower front to back ratio FPR), side lobe level(SSL) and X polarization, causing an undesirable interference with nearby communication systems.

In the case of EM energy dissipation(absorption), antenna’s efficiency is reduced significantly, decreasing device’s battery life, leading to a relatively large device volume.

Ref: Fan Yang and Yahya Rahmat, EBG structures in antenna engineering, Cambridge university press2009, Dr R.B Waterhouse, microtrip patch antennas: A designer’s guide Springer science + Busness, 2002, G. Gaussetis, miniaturization of EBG structures for mobile applications, radio science vol.40,2005

PEC GND&PRINTEDMICROSTRIP(PA)

In all printed Microstrip(patch) antennas, dielectric substrates are used to support a conducting metal located above a perfect GND and help to:

.

Shortening the operating wavelength, thus reducing the antenna size.

Dissimilar materials implies different indexes of refraction, thus there will be reflection and diffraction at the boundary (GND_sub/sub patch/air), resulting in EM energy loss.

Trapped EM waves are known as surface waves, they travel horizontally along the surface until they reach the edge or corner, where they reflect and diffract gain and again, degrading both antenna’s farfield and near field performance.

Ref: Fan Yang and Yahya Rahmat, EBG structures in antenna engineering, Cambridge university press2009, Dr R.B Waterhouse, microtrip patch antennas: A designer’s guide Springer science + Busness, 2002

WHAT ARE SURFACE WAVES?

Surface waves are surface currents supported by all grounded substrates, and there exist two modes TE and TM, while decaying exponentially a long the surface.

.

In TM mode electric fields E extends vertically out of the surface, and it is supported by a surface with a

While in TE the electric fields E is parallel to the surface, and it is supported by a surface with

If a surface has both positive and negative reactance, it can support both TE and TM at the same time with a band gap around resonance.

Ref:, Cambridge university press2009, Dr R.B Waterhouse, microtrip patch antennas: A designer’s guide Springer science + Busness, 2002, Daniel Frederic” High impedance EM surfaces, UCLA PhD dissertation 1999,Frank B. Gross Frontiers in antennas: Next generation design and engineering, Mc Graw Hill 2011.

WHAT ARE SURFACE WAVES?(CONT.)

The following close form formula can be used to predict which modes are going to be generated( their cutoff frequencies values)

.

. n =0,2,4… for TM modes n=1,3,5 … for TE Modes

The lowest TM0 mode has 0 cut off frequency, therefore it appears in all substrate based antenna designs( with exception of an air sub).

Surface wave strength can be reduced by decreasing h and/or less energy coupled into surface waves. Albeit at the cost of reduced VSWR BW(AR BW) and efficiency, thus thicker and lower sub is preferred which however relatively increases the size of the antenna.

Surface waves effect can be neglected for ().

Ref:, Cambridge university press2009, Dr R.B Waterhouse, microtrip patch antennas: A designer’s guide Springer, Girish Kumar et al.,” Broadband microtrip antennas Artech House 2002

It is obvious that :

OVERCOMING SURFACE WAVES EFFECTS

Why PEC GND supports surface waves? Because it represents a low impedance to all incoming waves( ) which can be

increased by employing an abstract perfect magnetic conductor(PMC).

High impedance surface(HIS) GND also known as artificial magnetic conductor (AMC) or reactive impedance surface (RIS) are periodic structure artificially engineered to mimic the performance of PMC.

Beside, if the AMC has also surface wave band gap, it is called electromagnetic band gap(EBG) structure. Both AMC and EBG plays a crucial role in designing high performance compact low profile antennas( these two may not coincide over a band pass of interest).

Ref. Daniel Frederic” High impedance EM surfaces, UCLA PhD dissertation 1999, Ian .T McMachael.” A method for determining optimal EBG reflection phase for low profile dipole antenna, IEEE AP 2013

AMC GNDPECGND

M(P)A SURFACE WAVES SUPPRESSION: TRADITIONAL AND MODERN APPROACHES

.principle methods cons pros

(a) Increasing antenna size to stress down TM0 excitation

Require shorting pinLocated far away from the feed.

Narrow BW（ 0.3%）， high X-pol(15dB greater than original), larger lateral size(>)

Improved eff.89%Gain 4.3dBi

Parasitic elements( full patch and ring)

larger size(>)Not suitable for arrayNarrow BW

Improved eff.82%Gain 6.7dBi, BW 3.7%, x_pol 20dB below co_polar

(a) Multilayer/superstrate(1984)Upper layer drains out surface waves generated by lower layer.

Multilayered/ modified superstrate( full patch and ring)

Both layer should be as thin as possible(100% eff.), narrow VSWR BW

Eff.78%,BW3.3%,30dB x_pol below co_pol, gain 6.5dBi

High for lower substrate and low for upper superstrate(Hi-L0)

Not suited for conformal applications (thicker structure)

BW(30%), eff.>85%, x_pol20 below co_pol, gain 7.5dBi, compatible with MMIC and OEIs

(b)Lowering under the patch( thick sub. Under and thin sub around patch )

Micromachining/stair step like substrate and cavity structure.

Larger size than the originalPatch –step substrate spacing needs care attention(not too large not too small)

Less back radiation, BW 4.6%

(b)Provide both HIS and surface wave bandgap

Periodic structure (shorted capacitive FSS via vias) or UC EBG

Difficult to fabricate require large GND

Considerable improvement in all antenna performance(near and far field)For(a) : benchmark antenna has BW1.9%,eff 66% gain 3.8dBi h=1.905mm

Ref: Fan Yang and Yahya Rahmat, EBG structures in antenna engineering, Cambridge university press2009, Dr R.B Waterhouse, microtrip patch antennas: A designer’s guide Springer science + Busness, 2002,Ying Liu et al. low profile high gain slot antenna with fabry perot cavity and EBG, Electronic letters 19th February 2015.

HIS/AMC STRUCTURES CONTRIBUTION

High impedance surface(HIS/AMC), has a 0 reflection phase at resonance and it can be designed to also exhibit surface wave band gap. In that case it is known as EBG.

Ref: Fan Yang and Yahya Rahmat, EBG structures in antenna engineering, Cambridge university press2009, 2002,Ying Liu et al. low profile high gain slot antenna with Fabry Perot cavity and EBG, Electronic letters 19 th February 2015. ,Frank B. Gross Frontiers in antennas: Next generation design and engineering, Mc Graw Hill 2011.

HIS/AMC DEFINITION&HISTORY

High impedance surface(HIS/AMC), is a lossless reactive periodic structure(p<<), artificially engineered to control and interact with EM wave.

It exhibits very high impedance at resonance(HIS) and it can also be synthesized to exhibit surface wave gap(EBG).

𝑍 𝑠=𝑗 𝜛 𝐿

1−𝜛2 𝐿𝑐

1954 corrugated surfaces(BG)

1959 reactive surfaces

1983 reactive surface using an artificial dielectric

1993 planar thin 2D AMC/HIS & Idea for reconfigurable HIS

1999 planar thin with AMC&EBG

Bulky (a

)

Thin(b)

Enhancement of(b

)

𝜛 0=1

√𝐿𝐶Ref: Fan Yang and Yahya Rahmat, EBG structures in antenna engineering, Cambridge university press2009, 2002,Ying ,Frank B. Gross Frontiers in antennas: Next generation design and engineering, Mc Graw Hill 2011. Debatosh Guha and Yahia, Microstrip and printed antennas, New trends, techniques and applications ,Wiley 2011

1956 Fabry Perot cavity resonant antenna

2005 planar EBG in the GND(DGS)

HIS/AMC STRUCTURES CHARACTERIZATION

For a small unit cell (<< ) strikes normally by a plane wave, its band gap position and width can be described using surface impedance model.

Moreover, since the unit cell size is (<<), its electromagnetic performance characteristics can be described using // circuit with lumped element(LC) .

HIS/AMC in phase reflection BW can be estimated using 45 the so called matching BW. Whereas, surface wave band gap is calculated using dispersion diagram.

Ref: Fan Yang and Yahya Rahmat, reflection phase characterizations of the EBG GND for low profile wire antenna, IEEE AP 2003 ,Frank B. Gross Frontiers in antennas: Next generation design and engineering, Mc Graw Hill 2011,M. Faisal Abedin, effects of EBG reflection phase profiles on the input impedance and BW of ultrathin directional antennas, IEE AP 2005

WEAKNESSES OF THE ORIGINAL HIS/AMC/RIS

Both surface wave band gap BW and in phase BW, depend upon the electrical() property and physical size of the substrate(thickness), capacitance C depends upon the unit cell periodicity/shape whereas inductance L depends on the sub’s h and

No loss-less magnetic material available above L band, requiring a thicker and large unit cell at low RF and microwave frequency.

Different solutions exist for wide band/multiband, reconfigurable and miniaturized AMC design.

For instance a unit cell capacitor can be adjusted(tuned) by using electrically stimulated devices such as RF MEMS, Varactor/pin diode or by using multi-layer configuration. Inductor (L)can be increased by using a magnet or by increase sub’s thickness.

Ref: Frank B. Gross Frontiers in antennas: Next generation design and engineering, Mc Graw Hill 2011

Ilaria Gallina et al.,” Aperiodic tiling based mush room type high impedance surfaces. IEEE propagations and wireless,2008 Jeremiah et al. Reconfigurable and tunable metamaterials: A review of theory and applications ,Hindawi international journal of antenna and propagation ,May 2014. Jodie M.Bell, UWB hybrid EBG/ferrite GND for low profile antennas,IEEE AP 2007

IMPROVING CONVENTIONAL AMC/HIS STRUCTURE PERFORMANCE

Ref: Frank B. Gross Frontiers in antennas: Next generation design and engineering, Mc Graw Hill 2011; Ilaria Gallina et al.,” Aperiodic tiling based mush room type high impedance surfaces. IEEE propagations and wireless,2008; Jeremiah et al. Reconfigurable and tunable metamaterials: A review of theory and applications ,Hindawi international journal of antenna and propagation ,May 2014. Jodie M.Bell, UWB hybrid EBG/ferrite GND for low profile antennas ,IEEE AP 2007, H.S. Youn,”design of cylindrical long slot array antenna integrated with hybrid EBG/ferrite GND IEEE antenna and wireless,2012,Nagendra kushwaha,” study of different shape EBGs for single and dual band,journal of microwave,optielectronic and Em applications,2014; Soheil Sadaat, composite metamaterial and metasurface integrated with non foster active circuit elements: A bandwidth enhancement investigation, IEEE AP 2013; Bin liang et al. frequency and polarizaiton reconfig. Antenna using active EBG structure for satellite application, IEEE Ap 2015.

AMC/HIS PERFORMANCE ENHANCEMENT COMPARISON

BW enhancement techniques comparisons

methods

wideband multiband reconfigurable

cons (a)Thicker unfeasible at UHF band(b) Immature , difficult to realize, stability and linearity problem(c) lossy, not available above L band (d) Longer simulation time

(1) Complicated ( optimization of h, geometry and size), asymmetric structure, narrow BW(2) thick, difficult to fabricate, narrow BW(3) Rely on computer simul., narrow BW( try and error)

(i1) limited high power handling capacity DC and RF isolation, not suited for>10GHz

(i2) no negligible insertion(loss), poor isolation and linearity

(i3)discrete reconfig, high loss no 0 RF series, high actuation voltage(70-150V) and fabrication tolerance, expensive

(iia) complex (practically unfeasible)reconfig. Low speed

(iib) lossy , narrow BW

pros (a) Literally loss less(b) Very wide (10:1)

(c) Compact, very wide low loss1.7:1BW lossy 40.5:1BW

(d) Both multiband and wideband

(1)More than two bands(6.3%GSM900,2.85 %GPS and1.97%GSM1800

(2) easy to achieve multiband, dependence on (Lt) and overlap area(Ct)

(3) simple to achieve multiband, compact

(i1) Continuous reconfig., thin,3:1Reconfig.BW , low power(>1W), speed ns

(i2) thin with power capacity(>10W),compactible with CMOS(3-5V), speed (ns) and High reliability

(i3) high linearity and DC-RF isolation, voltage(<100V), power >1W and speed

(iia) high power handling, linearity and electronic method can be incorporated.(iib) ease of integration

REVIEW ON THE CONVENTIONAL RECONFIG. MICROSTRIP (PATCH)ANTENNA

Antenna designed to reversely and intentionally change its performance characteristics ( near fields and far fields).

Goal: Overall system miniaturization and performance enhancement .

Practical considerations:

Design complexity and efficiency. Practicality of the proposed design paradigm. Overall system performance after the addition of reconfigurability.

Implementation:

Reconfigurability can be implemented in wide variety of ways.

What is a reconfig. Antenna?:

Ref: Frank B. Gross Frontiers in antennas: Next generation design and engineering, Mc Graw Hill 201; Debatosh Guha and Yahia, Microstrip and printed antennas, New trends, techniques and applications ,Wiley 2011

Pattern reconfig. Antenna.

Frequency reconfig. Antenna.

REVIEW ON THE CONVENTIONAL RECONFIG. MICROSTRIP ANTENNA(CONT.)

Ideal requirements for the control devices:

Reconfiguration principle:

Altering electrical properties of either spacer layer and/or conducting metal including: metal shape and size, metal conductivity, spacer layer , and h and GND.

Why microstrip antenna ?:

For a fixed radiating element shape and size on a substrate with h; Fr and BW of the MA are inversely and directly proportional to the (, ) and h, respectively.

Tunable materials and switches can be easily integrated into its planar structure, specifically in the GND, patch itself or in the spacing layer.

Relatively high tuning speed, better linearity and isolation ,low power consumption along with power handling capability(power depends on the applications) .

Ref: Frank B. Gross Frontiers in antennas: Next generation design and engineering, Mc Graw Hill 201; Debatosh Guha and Yahia, Microstrip and printed antennas, New trends, techniques and applications ,Wiley 2011

REVIEW ON THE CONVENTIONAL RECONFIG. MICROSTRIP (PATCH)ANTENNA(CONT.)

Ref: Frank B. Gross Frontiers in antennas: Next generation design and engineering, Mc Graw Hill 201; Debatosh Guha and Yahia, Microstrip and printed antennas, New trends, techniques and applications ,Wiley 2011,Shing Lung Steven et al.,” Frequency reconfigurable U-slot MPA, IEEE antennas and wireless propagation,2008,Mohannad M. Fajharian et al. reconfigurable Multiband extended U-slot antenna with switchable polarization for wireless applications,IEEE antennas and magazine April 2015, Pei Yuan Qin,” A pattern reconfigurable U-slot antenna and its applications in MIMO systems, IEEE AP February 2012

AMC/HIS/RIS IN COMPACT MICROSTRIP ANTENNA DESIGN

Antenna’s size, cost and profile can be reduced via traditional methods such as meandering , shorting pin, folding and dielectric and magnetic materials loading among others.

What we know:

But why narrow BW and low eff.?

The price we pay is narrow BW, low efficiency and antenna is sensitive to the nearby conductors(installation environment) or user in case of mobile phone.

Many reasons: (1) high dielectric constant material used supports current surface(SW) (2) antenna current and its image are in out phase, destructive interference.

Ref: Frank B. Gross Frontiers in antennas: Next generation design and engineering, Mc Graw Hill 201; Debatosh Guha and Yahia, Microstrip and printed antennas, New trends, techniques and applications ,Wiley 2011

AMC/HIS IN COMPACT MICROSTRIP ANTENNA DESIGN(CONT.)

Problem solved: The reflectivity of FSS and AMC can be used to reduce antenna’s profile while surface

wave band gap enables us to eliminate undesirable SW.

In addition surface wave band gap can be used to decouple antenna from its nearby conducting material, increasing devices battery life while reducing its size.

Generally speaking, AMC(EBG) structures are good candidate for compact directional wideband, multiband and multifunctional antennas design.

Ref: Frank B. Gross Frontiers in antennas: Next generation design and engineering, Mc Graw Hill 201; Debatosh Guha and Yahia, Microstrip and printed antennas, New trends, techniques and applications ,Wiley 2011;Fillipo Costa,” an active high impedance surface for low prole tunable and steerable antennas,IEEE antennas and wireless,2008;Basit A. Zeb,” Performance analysis of classical and phase corrected EBG resonator antennas with all dielectric superstrates, IET 2016, Y M Pan et al.,”A low profile high gain and wideband filtering antenna with metasurface,” IEEE AP May 2016,Sang Il kwak,” Design of PIFA with metamaterials for body SAR reduction in wearable applications, IEEE EM compatibility letters February 2017.

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AMC/HIS IN COMPACT MICROSTRIP ANTENNA DESIGN(CONT.)

AMC can do so much more: To completely surround radiating element and contributes positively to the antenna gain,

efficiency, SLL , FBR improvement.

Used as backing GND plane to greatly enhance antenna(array) VSWR and AR BW.

Used as backing ground plane, to reduce the profile required in the design of partial reflecting surface(PRS) high gain antenna known as EBG defect modes which is based on Fabry-Perot principle( to )

Utilized for the design of multiband( notch band), and reconfigurable antenna( pattern steering, frequency shifts and polarization)

Ref: Frank B. Gross Frontiers in antennas: Next generation design and engineering, Mc Graw Hill 2011; Kush Argawal,” wideband circular polarized AMC Reflector backed aperture antenna,IEEE AP Maech 2013; M.A Abdalla,” a dual notch UWB antenna using double inversed U-shaped EBG, IEEE conference 2016;N. Nasimuddin,” Bandwidth enhancement of single fed CP antenna using a metasurface, IEEE antennas and magazine, April 2016.

AMC/HIS IN COMPACT MICROSTRIP ANTENNA DESIGN(CONT.)

AMC can do so much more: Used as defect ground structure (DGS) plane to reduce antenna size and suppress

high order mode, increase bandwidth and reduce X-pol, further metasurface can be used to reduce large radar cross section of the MPA.

Used as an antenna itself and to reduce mutual coupling in antenna array, thus decreasing blind scan in phase array design .

Ref: Qian Li,” miniaturized dual layer Ebg structures for broadband mutual coupling reduction between UWB monopole antennas, IEEE AP March 2015; M.I. ahmed mutual coupling reduction in uWB slotted antennas array using UCEBG structures for wireless applications, IEEE conference 2016, Cheng Huang et al.,”Wide band RCS reduction of a stacked patch array antenna using a metasurface, IEEE antennas and wireless letters 2015;Abhijyoti et al. RMPA on slot-type GND for reduced X-pol radiation, IEEE wireless 2015, Chandrakanta et al. reduction in X-pol raditation of MPA using geometry independent resonator type DGS, IEEE AP june 2015;Ian T McMachael et al. A method for determining optimal EBG reflection phase for low profile dipole antenna design, IEEE AP 2013