Design of Series-Fed Bandwidth-Enhanced Microstrip Antenna …downloads.hindawi.com/journals/ijap/2019/3857964.pdf · 2019. 7. 30. · ResearchArticle Design of Series-Fed Bandwidth-Enhanced

Research ArticleDesign of Series-Fed Bandwidth-Enhanced Microstrip AntennaArray for Millimetre-Wave Beamforming Applications

Hung-Chen Chen 1 Tsenchieh Chiu 1 and Ching-LuhHsu2

1National Central University Taoyuan Taiwan2National Chung-Shan Institute of Science and Technology Taoyuan Taiwan

Correspondence should be addressed to Tsenchieh Chiu tcchiueencuedutw

Received 20 February 2019 Revised 15 April 2019 Accepted 15 May 2019 Published 3 June 2019

Academic Editor Ikmo Park

Copyright copy 2019 Hung-Chen Chen et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

A novel series-fedmicrostrip patch array antenna for 3739GHz beamforming is proposed To improve the antennabandwidth twoof the patches are modified with truncated corners in the diagonal directionThis truncation generates two degenerate resonanceswhich result in a flattened frequency response of the input impedanceThen the recessedmicrostrip feeds for the other two patchesare designed to yield a proper current distribution for radiation while maintaining minimal return loss wide bandwidth and lowsidelobes Though the individual patch antenna is elliptically polarized due to the truncated corners a phased array with linearpolarization can still be obtained by alternately deploying left-handed and right-handed elliptically polarized patches For validationof the proposed design an array is fabricated with 16 elements on a substrate with 10 mil thickness and 120576119903 =22 The beamformingcapability of the proposed array is also demonstrated The experiment results agree well with the simulation and show that theantenna gain and the return loss bandwidth can be more than 21 dBi and 8 respectively

1 Introduction

Recent researches have shown that millimetre-wave spec-trum is capable of providing the capacity required for futurewireless data applications including cellular systems [1 2]LAN [3] fixed access and backhaul [4] In the next genera-tion of the International Mobile Telecommunications (IMT)themillimetre-wave technique has been among one of the keytechnologies [5] The Federal Communications Commission(FCC) has taken the initiative to approve the use of severalbands in millimetre spectrum for 5G systems [6] To takeadvantage of the large bandwidth in millimetre wave thesystem gain has to be significantly increased to compensatethe severe propagation losses which are intrinsic in thisspectrum Active phased array with beamforming capabilityis an effective approach to achieve high performance for 5Gmillimetre-wave systems The cost to implement an activearray however may be quite high Fortunately the contin-uous advancement of device technology makes it possible tobuild such an array cost-effectively [1]

Various types of antenna arrays have been proposedfor 28 37 and 39 GHz systems [7ndash15] In [7] a 28-GHz4times2 circular-polarization microstrip antenna subarray isdesigned In [8] a 28-GHz 16-element mesh-grid patchantenna array is realized on a multilayer FR4 with low radia-tion efficiency In [9] a switchable phased array composed ofthree subarrays of patch antennas is proposed for coverageextension Each subarray can cover plusmn 40∘ scanning rangeby controlling phase shifter assemblies (PSA) In [10] a2838 GHz dual-band microstrip printed slot antenna arrayis proposed In [11] 2times2 and 3times3 series-fed patch arrays for28-GHz beam-steering applications are designed In [12] a37-GHz dual-polarized 2times2 subarray antenna is realized bysubstrate-integrated waveguide (SIW) on low-temperaturecofired ceramic (LTCC) Due to low profile light weightand readiness for both fabrication and integration it can beseen that microstrip antennas are suitably employed for the5G millimetre-wave systems Series-fed structures are oftenused in many millimetre-wave patch array antennas [13ndash15]especially for the systems in the 3739-GHz band because

HindawiInternational Journal of Antennas and PropagationVolume 2019 Article ID 3857964 10 pageshttpsdoiorg10115520193857964

2 International Journal of Antennas and Propagation

Table 1 Comparison of reference

Ref elements f0(GHz) BW() SLL(dB) Scan EIRP(dB)[7] 8 28 47[9] 8 215 32 plusmn40∘[10] 8 2838 5 plusmn20∘[16] 5 5 24[17] 48 60 25 7 plusmn32∘[20] 64 28 13 plusmn30∘ 37[21] 32 29 21 plusmn50∘ 41This work 64 375 8 25 plusmn40∘ 48

L1 L2 L3 L4

W1 W4W3W2

x

y

D1 D2 D3U1 U1U2 U2

t

W0

(a)

(b)

Figure 1 (a) The proposed and (b) the conventional series-fed array of microstrip patches

the less complexity of the feeding circuits is preferred for theantenna gain enhancement From the comparison in Table 1[7 9 10 16 17] it can be seen that the impedance bandwidthsof the series-fed antenna arrays range from 24 to 5 Thebandwidth of microstrip antenna on a thin laminate tendsto be narrow often less than 3 [18 19] For the band from37 to 386 GHz the bandwidth is required to be at least43 [6] A multitude of structures may be used to increasethe bandwidth of microstrip antenna for example stackedpatches [19]However the structure complexity can often leadto extra loss

Base station antennas are generally required to havehigh gain beam steering or multibeam capability for multi-frequency applications Active electronically scanned arrays(AESAs) are a promising technology to address the 5G basestation antenna design AESAs can shift the beam with agilitywhile exhibiting real-time beam control low side-lobe highgain wide scan angle wide bandwidth and MIMO capa-bilities [20 21] A comparison of the important parameterssuch as frequency number of elements bandwidth (BW)side-lobe level (SLL) scan coverage and effective isotropicradiated power (EIRP) has been summarized in Table 1

The focus of the paper is on developing a 3739GHzactive phased array with the beamforming capability in theazimuthal direction In the vertical direction the patchesare combined by a series-fed configuration which yieldsa fixed beam shape in the elevation direction Also the

return loss bandwidth of the array will be more than 8The outline of this paper is as follows Section 2 describesthe modified series-fed patch antenna featuring improvedbandwidth and low loss The procedure to increase thebandwidth is given and demonstrated by a series-fed antennawith four patches The formation of a 16-element array basedon the designed four-patch array is addressed The weightingcoefficients required in the beamforming system are alsodiscussed In Section 3 the simulation and experiment resultsare presented and compared Finally a conclusion is given inSection 4

2 Antenna Array Design

21 Bandwidth-Enhanced Series-Fed Microstrip Patches Theproposed and the conventional series-fed array of microstrippatches are illustrated in Figures 1(a) and 1(b) respectivelyIn the figure four resonant patches are connected usinga single straight transmission line The frequency responseof the input impedance of a single patch is simulated andshown in Figure 2 When the patch is not perturbed as inFigure 1(b) one resonance is observed at 374 GHz If theopposite corners are truncated as in Figure 1(a) the resonancesplits into two degenerate modes [18 22] A patch on theDuroid 5880 substrate with 120576119903 = 22 h (thickness)=10 milW4= 25mm and L4 = 256mm is designed and simulated It canbe shown in Figure 2 that larger truncation (t) leads to more

International Journal of Antennas and Propagation 3

40

30

20

10

0

Conventional t=2mm

t=4mmt=6mm

Retu

rn lo

ss (d

B)

365 370 375 380 385 390360Frequency (GHz)

(a)

Conventional t=4mm

minus50

0

50

100

Re(Z

) (O

hm)

365 370 375 380 385 390360Frequency (GHz)

(b)

Conventional t=4mm

minus100

minus50

0

50

100

Im(Z

) (O

hm)

365 370 375 380 385 390360Frequency (GHz)

(c)

Figure 2 Simulated performances of the truncated patch antennas (a) Return loss (b) Re(Z) and (c) Im(Z)

mode separation and wider bandwidth The radiated fieldsexcited by these two modes which are perpendicular to eachother are not linearly polarized Nevertheless pure linearpolarization can be achieved when left-handed and right-handed elliptical polarizations are adequately combined [23]

As shown in Figure 1(a) the two patches at the end ofthe array are arranged to produce y-directed linear polar-ization and retain the enhanced bandwidth The formationof the array can be designed to further lessen the cross-polarization radiation which will be discussed later Thewidth of the patch may be varied to achieve the desiredradiation conductance [24ndash28] To build a linear array withbeamforming capability however the patch width has tobe limited to less than the element spacing usually 1205822to avoid the unwanted mutual coupling between patchesdue to proximity The input impedance of the edge-fedpatch can be adjusted by using an inset feed recessed adistance from the edge [16] Furthermore at the first patcha quarter-wavelength transformer can be employed as thefeed line which can ease the realization of the required inputimpedance

When the width of the connecting line is fixed W0 = 02mm the dimensions of the series-fed patches are U1 =063U2 =012 L1 = 274 L2 = 274 L3 = 256 L4 = 256 W1 = 22W 2 = 22 W3 = 25 W 4 = 25 t = 04 and D1 = D2 = D3 =3 all in mmThe simulated values of the input impedance ofthe patches are given as follows Z1 = 1508 Z2 = 1508 Z3 =2625 and Z4 = 2627ohm respectively

Figure 2(a) shows that 66 bandwidth can be achievedfor the corner-truncated patch compared to only 26 band-width for the rectangular one if 10-dB return loss is specifiedAt resonance of 382GHz as shown in Figures 2(b) and 2(c)the real part of the input impedance is 546 ohm and theimage part of the input impedance is -34 ohm which isapproximately matched to the input impedance Z0 = 50 ohm

The layouts of four kinds of series-fed antennas areillustrated in Figure 3 The transmission line between twoadjacent patches is of about one half-wavelength (D0 = 4mm)For layouts (a) and (b) as shown in Figure 3 an inset feedis used for the first patch The width and the depth of thesymmetrical rectangular notches can be tuned for impedancematching Figure 4 shows that 66 bandwidth can beachieved for layout (a) compared to only 17 bandwidth forlayout (b) if 10-dB return loss is specified Without the insetfor the first patch layouts (c) and (d) cannot achieve 10-dBreturn loss requirement because of high input impedance

The simulated H-plane and E-plane radiation patternsare plotted in Figures 5(a) and 5(b) respectively It canbe seen that the antenna gain can be at least 10 dBi withthe first sidelobe suppression more than 13 dB The H-plane cross-pol isolation however is only 10 dB The cross-pol performance can be improved by the array formationdescribed in Section 22

22 Array Design to Reduce Cross-Polarization In the forma-tion of a linear array based on the proposed series-fed patch


D0

Z1

Z2

Z3

Z4

(a) (b) (c) (d)x

y

Figure 3 The layouts of four kinds of series-fed antennas (a)sim(d) with the left-handed and the right-handed elliptical polarization types

(a)(b)

(c)(d)

40

30

20

10

0

Retu

rn lo

ss (d

B)

37 38 3936Frequency (GHz)

Figure 4 Series feed layout (a)sim(d) return loss simulation

antennas left-handed and right-handed elliptical polariza-tion patches are alternately used as shown in Figure 3(a) forfurther reducing the cross-polarization radiation For thesetwo elliptical polarization types the electric field can be ingeneral respectively expressed as

997888119864 = 1198640 (119895120572997888119886 119909 + 997888119886 119910) (1a)

997888119864 = 1198640 (minus119895120572997888119886 119909 + 997888119886 119910) (1b)

where 120572 can be regarded as the residual axial ratio |997888119864119909||997888119864119910|for a single series-fed antenna Figure 6 shows the geometricallayout of a linear array with even number of elements Thearray factor can be expressed as [29]

119873

sum119899=1

119886119899997888119864119899119890119895(2120587120582)119909119899 sin(120579119886minus1205791015840

119886) (2)

where an En and 120579rsquoa denote the complex weighting elementpattern and the beam direction respectively IfN is even thepattern can be shown to be1198732

sum119899=1

2 (119886119899997888119864119899 + 119886119873+1minus119899997888119864119873+1minus119899) cos [2120587120582 (119873 + 12 minus 119899)119889 sin (120579119886 minus 120579

1015840119886)] (3)

where d is the element spacing The x-directional electricfields of the n-th and (N+1ndashn)-th elements can cancel witheach other if the elliptical polarization types are different andthe following condition is satisfied

119886119899 = 119886119873+1minus119899 (4)

The cross-polarization radiation can be therefore reduced inthe main beam direction The condition of (4) for amplitudeweightings can be readily achieved in various beamformingapplications for example the well-known Taylor and Baylissbeams [29 30] It is noted that the azimuthal pattern issymmetric in theory when (4) is applied Figure 7 shows thesimulated H-plane and E-plane patterns of the 4times2 series-fedantennas that is n = 2 In Figure 7 it can be seen that thecross-polarization radiation is insignificant

3 Beamforming Simulation andExperiment Results

Figure 8 shows the photograph of the fabricated 4times16 arraybased on the proposed series-fed patch antennas with thespacing dx = 4 mm For accommodating transmitreceivemodule (TRM) to be installed from behind an additionalsection of 50-ohm microstrip line 447 mm in length isalternately employed to connect the array and the probe feedThis extra microstrip line is compensated by the TRM whichintegrates millimeter-wave components including a poweramplifier (PA) a low-noise amplifier (LNA) an attenuator aphase shifter and switches The least significant bits (LSB) ofthe phase shifter and the attenuator correspond to 1125∘ and1 dB respectively


Co PolCross Pol

minus150 minus120 minus90 minus60 minus30minus180 30 60 90 120 150 1800Azimuth (degree)

minus50

minus40

minus30

minus20

minus10

0

10

20A

mpl

itude

(dB)

(a)

Co PolCross Pol

minus150 minus120 minus90 minus60 minus30minus180 30 60 90 120 150 1800Elevation (degree)

minus50

minus40

minus30

minus20

minus10

0

10

20

Am

plitu

de (d

B)

(b)

Figure 5 Simulated co-pol and cross-pol patterns of the proposed 4times1 series-fed antenna (a) H-plane and (b) E-plane

Table 2 The bit steps of the TR modules for the gains and phases

Control state Attenuator38GHz

Phase shifter38GHz

Transmit gain38GHz

Receive gain38GHz

00000 0 7043 271 23400001 -113 6004 2597 222700010 -188 4582 2522 215200100 -365 2437 2345 197501000 -724 -2022 1986 161610000 -1482 -1138 1228 85811111 -3021 7941 -311 -681

X

Y

Z

d

P(r )

2

2+1

Figure 6The geometrical layout of a linear array with even numberof elements

Each series-fed patch array is connected to a TR modulethrough K type semirigid cable assembly as shown inFigure 9 Figure 10 shows the feeding network of the arrayIn this network a WR28 2-way power combiner is used toconnect two WR28 8-way power combiners each of whichconnects eight TR modules

The TR modules fabricated by Transcom as shown inFigure 11 are designed for the active phased array applicationPower amplifiers are used to achieve the output power upto 05W The noise figure of the low-noise amplifier (LNA)is less than 68dB The 5-bit HMC939 attenuator and the5-bit TGP2102 phase shifter are employed to adjust theamplitude and the phase with 1dB and 1125∘ resolution

respectively They are located in the common arm of trans-mit and receive path A digital compensation algorithm isapplied to increase the phase accuracy within plusmn5625∘ andthe amplitude accuracy within plusmn05dB These algorithms areimplemented by FPGAandflashmemorywith a lookup tableThe transmitter P1dB and the receiver gain are 271dBm and234dB respectively The typical values for gain and phase areshown in Table 2

The probe feed of 15-mil in length is the pin extendedfrom the center of a 50-ohm coaxial structure integrated withthe back-plate This configuration results in good isolationbetween TRM and antennas which in turn avoid affectingthe radiation pattern The measured return losses are shownin Figure 12(a) for the 1st 7th 8th and 16th elements inFigure 8 which are located at the border and the middle ofthe array These four elements exhibit the effects of differentdegrees of mutual coupling from the adjacent elements Thereturn losses are below -10 dB from 36 to 39 GHz It isobserved that the measured bandwidth can be slightly morethan 8 Figure 12(b) shows the experiment results of theisolation between the adjacent elements which are at least20dB

In the phased array the uncorrelated amplitude andphase errors of each element caused by active devices anddiscontinuities can be corrected by near-field alignment[31] In this measurement procedure an iterative process isdeveloped to optimally set the states of the 5-bit phase shifters


Co PolCross Pol

minus50

minus40

minus30

minus20

minus10

0

10

20A

mpl

itude

(dB)

1209060300 150 180minus60minus90minus120minus150 minus30minus180

Azimuth (degree)

(a)

Co PolCross Pol

minus50

minus40

minus30

minus20

minus10

0

10

20

Am

plitu

de (d

B)


Elevation (degree)

(b)

Figure 7 Simulated antenna patterns of the proposed 4times2 series-fed array antennas with reduced cross-polarization (a) H-plane and (b)E-plane

Figure 8 The photograph of the fabricated 4times16 array

Figure 9 The connection of antennas and TR modules

Figure 10 The photograph of the fabricated power combiner

(a)

(b)

Figure 11 The photographs of the Transcom TR modules (a) topview (b) side view

and attenuators until the measured gain and phase of eachantenna can converge within plusmn05 dB and plusmn5625∘ respec-tively Figures 13(a) and 14(a) present themeasurements of theantenna patterns of the aligned 4times16 array with the uniformand low-sidelobe distributions respectively For the patternwith low sidelobes the weighting coefficients are assigned tondash13 ndash14 ndash6 ndash5 ndash3 ndash1 ndash1 0 0 ndash1 ndash1 ndash3 ndash5 ndash6 ndash14 and ndash13dB for n = 1sim16 It is noted that the E-plane patterns shown inFigures 13(b) and 14(b) exhibit a similar performance

Figures 15(a) and 16(a) present the simulated and themea-sured results of the transmitting patterns with the uniformdistribution for 376GHzwith beam steering along horizontal


SimuMeas(P1)Meas(P7)

Meas(P8)Meas(P16)

365 370 375 380 385 390360Frequency (GHz)

50

40

30

20

10

0

Retu

rn lo

ss (d

B)

(a)

Meas(P2-P1)Meas(P4-P3)Meas(P6-P5)Meas(P8-P7)


35

30

25

20

15

10

5

0

Isol

atio

n (d

B)

365 370 375 380 385 390360Frequency (GHz)

(b)

Figure 12 Measured and simulated antenna performances of the 4times16 series-fed array antennas (a) return loss and (b) isolation

369GHz3725GHz376GHz

3795GHz383GHz

minus30

minus20

minus10

0

Am

plitu

de (d

B)

40200 60 80minus40minus60 minus20minus80Azimuth (degree)

(a)

369GHz3725GHz376GHz

3795GHz383GHz

minus30

minus20

minus10

0A

mpl

itude

(dB)

40200 60 80minus40minus60 minus20minus80Elevation (degree)

(b)

Figure 13Themeasurement of the transmitting pattern of the aligned 4times16 array with the uniform distribution (a) H-plane and (b) E-plane

369GHz3725GHz376GHz

3795GHz383GHz

minus30

minus20

minus10

0

Am

plitu

de (d

B)


(a)

369GHz3725GHz376GHz

3795GHz383GHz

minus30

minus20

minus10

0

Am

plitu

de (d

B)


(b)

Figure 14 The measurement of the receiving pattern of the aligned 4times16 array with low sidelobes (a) H-plane and (b) E-plane


-20deg-10deg0deg

10deg20deg

minus30

minus20

minus10

0A

mpl

itude

(dB)


(a)

-40deg-20deg0deg

20deg40deg

minus30

minus20

minus10

0

Am

plitu

de (d

B)


(b)

Figure 15 The simulation of the scanned H-plane patterns (a) transmitting patterns with uniform distribution and (b) receiving patternswith low sidelobes

-20deg-10deg0deg

10deg20deg

minus30

minus20

minus10

0

Am

plitu

de (d

B)


(a)

-40deg-20deg0deg

20deg40deg

minus30

minus20

minus10

0A

mpl

itude

(dB)


(b)

Figure 16Themeasurements of the scannedH-plane patterns (a) transmitting patterns with uniform distribution and (b) receiving patternswith low sidelobes

directions by every 10∘ in the range of plusmn 20∘ The main beamof the boresight exhibits the beamwidth of 55∘ while the firstsidelobe rejection is approximately ndash13 dB When the mainbeam scans to plusmn20∘ the beamwidth becomes 65∘ and thescan loss is about 1 dB Figures 15(b) and 16(b) present thesimulation andmeasurement of the receiving patterns for 376GHz with beam steering along horizontal directions by every20∘ The main beam of the boresight exhibits the beamwidthof 79∘ with 25 dB sidelobe rejection When the main beamscans to plusmn 40∘ the beamwidth becomes 10∘ and the scan lossis about 21dBThe sidelobe rejection is only 18 dBmainly dueto the induced variations of the active devices in TRM

Figures 17(a) and 17(b) show the H-plane and E-planecross-polarization for the antenna with low-sidelobe weight-ings In both cases it can be seen that the cross-polarizationis generally less than -20 dB It is found that the rectangularpatches arranged on the peripheral of the array antenna canreduce the cross-polarization radiation

Themeasured gain curve of the 4times16 array is in agreementwith the predicted gain obtained from the HFSS simulationas shown in Figure 18 The measured gain of array isapproximately 21sim22 dBi after the near-field alignment isachieved It can be seen that the measured receiver gain staysfairly constant from 37 to 39 GHz

4 Conclusion

In the paper a novel configuration of microstrip series-fedpatch array has been designed to enhance the bandwidthCompared with the conventional one this novel configura-tion has been verified to have a 21-dBi gain for 8 bandwidthby experiment The proposed antenna can be used for 3739bandswhich is under the consideration for 5G applications A4 times 16 planar array has been prototyped and shown to exhibitgood radiation characteristics in beam steering and sidelobesuppression This active antenna offering high gain good


376GHz

minus50

minus40

minus30

minus20

minus10

0Cr

oss-

pola

rizat

ion

ampl

itude

(dB)


(a)376GHz

minus50

minus40

minus30

minus20

minus10

0


Cros

s-po

lariz

atio

n am

plitu

de (d

B)

(b)

Figure 17 The measured cross-polarization of the antenna with low-sidelobe weightings (a) H-plane and (b) E-plane

SimuMeas

19

20

21

22

23

24

25

Gai

n (d

B)

375 380 385 390370Frequency (GHz)

Figure 18 The measured and simulated gain curves of the 4times16array in the broadside direction

cross-polarization isolation and flexible radiation patterns issuitable for millimetre-wave beamforming applications

Data Availability

The data used to support the findings of this study areincluded within the article

Conflicts of Interest

The authors declare that there are no conflicts of interestregarding the publication of this paper

Acknowledgments

This work was supported by the Ministry of Science andTechnology ROC under grant MOST106-2221-E-008 -010

References

[1] T Rappaport S Sun R Mayzus et al ldquoMillimeter wave mobilecommunications for 5G cellular it will workrdquo IEEE Access vol1 pp 335ndash349 2013

[2] W Roh J-Y Seol J Park et al ldquoMillimeter-wave beamformingas an enabling technology for 5G cellular communications the-oretical feasibility and prototype resultsrdquo IEEECommunicationsMagazine vol 52 no 2 pp 106ndash113 2014

[3] A Ghosh T A Thomas M C Cudak et al ldquoMillimeter-wave enhanced local area systems a high-data-rate approachfor future wireless networksrdquo IEEE Journal on Selected Areas inCommunications vol 32 no 6 pp 1152ndash1163 2014

[4] Z Pi J Choi and R W Heath ldquoMillimeter-wave Gbps broad-band evolution towards 5G Fixed access and backhaulrdquo IEEECommunications Magazine vol 54 no 4 pp 138ndash144 2016

[5] Resolution 238 ldquoStudies on frequency-relatedmatters for Inter-national Mobile Telecommunications identification includingpossible additional allocations to the mobile services on aprimary basis in portions of the frequency range between 2425and 86 GHz for the future development of IMT for 2020 andbeyondrdquo ITU WRC-15 2015

[6] FCC ldquoUse of spectrum bands above 24 GHz for mobile radiordquo2015

[7] H Zhou and F Aryanfar ldquoA Ka-Band patch antenna arraywith improved circular polarizationrdquo in Proceedings of the 2013IEEE International Symposium on Antennas and Propagationamp USNCURSI National Radio Science Meeting pp 225-226Orlando FL USA July 2013

[8] WHong K Baek Youngju Lee and YoonGeonKim ldquoDesignand analysis of a low-profile 28 GHz beam steering antennasolution for Future 5G cellular applicationsrdquo in Proceedings ofthe 2014 IEEEMTT-S International Microwave Symposium -MTT 2014 pp 1ndash4 Tampa FL USA June 2014

[9] N Ojaroudiparchin M Shen S Zhang and G F PedersenldquoA switchable 3-D-coverage-phased array antenna package for5G mobile terminalsrdquo IEEE Antennas and Wireless PropagationLetters vol 15 no 11 pp 1747ndash1750 2016

[10] M M Ali and A R Sebak ldquoDesign of compact millimeterwave massive MIMO dual-band (2838 GHz) antenna arrayfor future 5G communication systemsrdquo in Proceedings of the2016 17th International Symposium on Antenna Technology and


Applied Electromagnetics (ANTEM) pp 1ndash4 Montreal CanadaJuly 2016

[11] M Khalily R Tafazolli T A Rahman and M R KamarudinldquoDesign of phased arrays of series-fed patch antennas withreduced number of the controllers for 28-GHz mm-waveapplicationsrdquo IEEE Antennas and Wireless Propagation Lettersvol 15 pp 1305ndash1308 2016

[12] H Chu and Y-X Guo ldquoA filtering dual-polarized antennasubarray targeting for base stations in millimeter-wave 5Gwireless communicationsrdquo IEEE Transactions on ComponentsPackaging andManufacturing Technology vol 7 no 6 pp 964ndash973 2017

[13] T-Y Han ldquoSeries-Fed Microstrip Array Antenna with CircularPolarizationrdquo International Journal of Antennas and Propaga-tion vol 2012 Article ID 681431 5 pages 2012

[14] B H Ku P Schmalenber O Inac et al ldquolsquoA 77ndash81 16-elementphased-array receiver with plusmn50119900 beam scanning for advancedautomotive radarrdquo IEEE Transactions on MicrowaveTheory andTechniques vol 62 no 11 pp 2823ndash2832 2014

[15] S Krishna G Mishra and S K Sharma ldquoA series fed planarmicrostrip patch array antenna with 1D beam steering for 5Gspectrum massive MIMO applicationsrdquo in Proceedings of the2018 IEEE Radio and Wireless Symposium (RWS) pp 209ndash212Anaheim CA January 2018

[16] T Yuan N Yuan and L-W Li ldquoA novel series-fed taper antennaarray designrdquo IEEE Antennas and Wireless Propagation Lettersvol 7 pp 362ndash365 2008

[17] V Semkin F Ferrero A Bisognin et al ldquoBeam switchingconformal antenna array for mm-wave communicationsrdquo IEEEAntennas and Wireless Propagation Letters vol 15 pp 28ndash312016

[18] K R Carver and J W Mink ldquoMicrostrip antenna technologyrdquoIEEE Transactions on Antennas and Propagation vol 29 no 1pp 2ndash24 1981

[19] J R James and P S Hall ldquoHandbook of microstrip antennardquoin lsquoHandbook of microstrip antennarsquo p chap Peter Peregrinus1989

[20] B Sadhu Y Tousi J Hallin et al ldquoA 28GHz 32-element phased-array transceiver IC with concurrent dual polarized beams and14 degree beam-steering resolution for 5G communicationrdquo inProceedings of the 2017 IEEE International Solid- State CircuitsConference - (ISSCC) pp 128-129 San Francisco CA USAFeburary 2017

[21] K Kibaroglu M Sayginer andG M Rebeiz ldquoAn ultra low-cost32-element 28 GHz phased-array transceiver with 41 dBm EIRPand 10-16 Gbps 16-QAM link at 300 metersrdquo in Proceedings ofthe 2017 IEEE Radio Frequency Integrated Circuits SymposiumRFIC 2017 pp 73ndash76 USA June 2017

[22] M Haneishi T Nambara and S Yoshida ldquoStudy on ellipticityproperties of single-feed-type circularly polarised microstripantennasrdquo IEEE Electronics Letters vol 18 no 5 pp 191ndash1931982

[23] S Gao Q Luo and F Zhu Circularly Polarized Antenna JohnWiley amp Sons 2014

[24] A G Derneryd ldquoLinearly polarized microstrip antennasrdquo IEEETransactions on Antennas and Propagation vol 24 no 6 pp846ndash851 1976

[25] T Metzler ldquoMicrostrip series arraysrdquo IEEE Transactions onAntennas and Propagation vol 29 no 1 pp 174ndash178 1981

[26] B B Jones F Y M Chow and A W Seeto ldquoThe synthesis ofshaped patterns with series-fed microstrip patch arraysrdquo IEEE

Transactions on Antennas and Propagation vol 30 no 6 pp1206ndash1212 1982

[27] D G Babas and J N Sahalos ldquoSynthesis method of series-fedmicrostrip antenna arraysrdquo IEEE Electronics Letters vol 43 no2 pp 78ndash80 2007

[28] S Sengupta D R Jackson and S A Long ldquoA method for ana-lyzing a linear series-fed rectangular microstrip antenna arrayrdquoInstitute of Electrical and Electronics Engineers Transactions onAntennas and Propagation vol 63 no 8 pp 3731ndash3736 2015

[29] R J Mailloux Phased Array AntennaHandbook ArtechHouse2nd edition 2005

[30] H J Orchard R S Elliott and G J Stern ldquoOptimising thesynthesis of shaped beam antenna patternsrdquo IEE Proceedings H- Microwaves Antennas and Propagation vol 132 no 1 pp 63ndash68 1985

[31] W T Patton and L H Yorinks ldquoNear-field alignment ofphased-array antennasrdquo IEEE Transactions on Antennas andPropagation vol 47 no 3 pp 584ndash591 1999

International Journal of

AerospaceEngineeringHindawiwwwhindawicom Volume 2018

RoboticsJournal of

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Volume 2018

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Table 1 Comparison of reference

Ref elements f0(GHz) BW() SLL(dB) Scan EIRP(dB)[7] 8 28 47[9] 8 215 32 plusmn40∘[10] 8 2838 5 plusmn20∘[16] 5 5 24[17] 48 60 25 7 plusmn32∘[20] 64 28 13 plusmn30∘ 37[21] 32 29 21 plusmn50∘ 41This work 64 375 8 25 plusmn40∘ 48

L1 L2 L3 L4

W1 W4W3W2

x

y

D1 D2 D3U1 U1U2 U2

t

W0

(a)

(b)

Figure 1 (a) The proposed and (b) the conventional series-fed array of microstrip patches

the less complexity of the feeding circuits is preferred for theantenna gain enhancement From the comparison in Table 1[7 9 10 16 17] it can be seen that the impedance bandwidthsof the series-fed antenna arrays range from 24 to 5 Thebandwidth of microstrip antenna on a thin laminate tendsto be narrow often less than 3 [18 19] For the band from37 to 386 GHz the bandwidth is required to be at least43 [6] A multitude of structures may be used to increasethe bandwidth of microstrip antenna for example stackedpatches [19]However the structure complexity can often leadto extra loss

Base station antennas are generally required to havehigh gain beam steering or multibeam capability for multi-frequency applications Active electronically scanned arrays(AESAs) are a promising technology to address the 5G basestation antenna design AESAs can shift the beam with agilitywhile exhibiting real-time beam control low side-lobe highgain wide scan angle wide bandwidth and MIMO capa-bilities [20 21] A comparison of the important parameterssuch as frequency number of elements bandwidth (BW)side-lobe level (SLL) scan coverage and effective isotropicradiated power (EIRP) has been summarized in Table 1

The focus of the paper is on developing a 3739GHzactive phased array with the beamforming capability in theazimuthal direction In the vertical direction the patchesare combined by a series-fed configuration which yieldsa fixed beam shape in the elevation direction Also the

return loss bandwidth of the array will be more than 8The outline of this paper is as follows Section 2 describesthe modified series-fed patch antenna featuring improvedbandwidth and low loss The procedure to increase thebandwidth is given and demonstrated by a series-fed antennawith four patches The formation of a 16-element array basedon the designed four-patch array is addressed The weightingcoefficients required in the beamforming system are alsodiscussed In Section 3 the simulation and experiment resultsare presented and compared Finally a conclusion is given inSection 4

2 Antenna Array Design

21 Bandwidth-Enhanced Series-Fed Microstrip Patches Theproposed and the conventional series-fed array of microstrippatches are illustrated in Figures 1(a) and 1(b) respectivelyIn the figure four resonant patches are connected usinga single straight transmission line The frequency responseof the input impedance of a single patch is simulated andshown in Figure 2 When the patch is not perturbed as inFigure 1(b) one resonance is observed at 374 GHz If theopposite corners are truncated as in Figure 1(a) the resonancesplits into two degenerate modes [18 22] A patch on theDuroid 5880 substrate with 120576119903 = 22 h (thickness)=10 milW4= 25mm and L4 = 256mm is designed and simulated It canbe shown in Figure 2 that larger truncation (t) leads to more


40

30

20

10

0

Conventional t=2mm

t=4mmt=6mm

Retu

rn lo

ss (d

B)

365 370 375 380 385 390360Frequency (GHz)

(a)

Conventional t=4mm

minus50

0

50

100

Re(Z

) (O

hm)

365 370 375 380 385 390360Frequency (GHz)

(b)

Conventional t=4mm

minus100

minus50

0

50

100

Im(Z

) (O

hm)

365 370 375 380 385 390360Frequency (GHz)

(c)










D0

Z1

Z2

Z3

Z4

(a) (b) (c) (d)x

y


(a)(b)

(c)(d)

40

30

20

10

0

Retu

rn lo

ss (d

B)




997888119864 = 1198640 (119895120572997888119886 119909 + 997888119886 119910) (1a)

997888119864 = 1198640 (minus119895120572997888119886 119909 + 997888119886 119910) (1b)


119873

sum119899=1

119886119899997888119864119899119890119895(2120587120582)119909119899 sin(120579119886minus1205791015840

119886) (2)


sum119899=1


1015840119886)] (3)


119886119899 = 119886119873+1minus119899 (4)





Co PolCross Pol


minus50

minus40

minus30

minus20

minus10

0

10

20A

mpl

itude

(dB)

(a)

Co PolCross Pol


minus50

minus40

minus30

minus20

minus10

0

10

20

Am

plitu

de (d

B)

(b)




Phase shifter38GHz

Transmit gain38GHz

Receive gain38GHz

00000 0 7043 271 23400001 -113 6004 2597 222700010 -188 4582 2522 215200100 -365 2437 2345 197501000 -724 -2022 1986 161610000 -1482 -1138 1228 85811111 -3021 7941 -311 -681

X

Y

Z

d

P(r )

2

2+1








Co PolCross Pol

minus50

minus40

minus30

minus20

minus10

0

10

20A

mpl

itude

(dB)


Azimuth (degree)

(a)

Co PolCross Pol

minus50

minus40

minus30

minus20

minus10

0

10

20

Am

plitu

de (d

B)


Elevation (degree)

(b)





(a)

(b)






Meas(P8)Meas(P16)

365 370 375 380 385 390360Frequency (GHz)

50

40

30

20

10

0

Retu

rn lo

ss (d

B)

(a)



35

30

25

20

15

10

5

0

Isol

atio

n (d

B)

365 370 375 380 385 390360Frequency (GHz)

(b)


369GHz3725GHz376GHz

3795GHz383GHz

minus30

minus20

minus10

0

Am

plitu

de (d

B)


(a)

369GHz3725GHz376GHz

3795GHz383GHz

minus30

minus20

minus10

0A

mpl

itude

(dB)


(b)


369GHz3725GHz376GHz

3795GHz383GHz

minus30

minus20

minus10

0

Am

plitu

de (d

B)


(a)

369GHz3725GHz376GHz

3795GHz383GHz

minus30

minus20

minus10

0

Am

plitu

de (d

B)


(b)



-20deg-10deg0deg

10deg20deg

minus30

minus20

minus10

0A

mpl

itude

(dB)


(a)

-40deg-20deg0deg

20deg40deg

minus30

minus20

minus10

0

Am

plitu

de (d

B)


(b)


-20deg-10deg0deg

10deg20deg

minus30

minus20

minus10

0

Am

plitu

de (d

B)


(a)

-40deg-20deg0deg

20deg40deg

minus30

minus20

minus10

0A

mpl

itude

(dB)


(b)





4 Conclusion



376GHz

minus50

minus40

minus30

minus20

minus10

0Cr

oss-

pola

rizat

ion

ampl

itude

(dB)


(a)376GHz

minus50

minus40

minus30

minus20

minus10

0


Cros

s-po

lariz

atio

n am

plitu

de (d

B)

(b)


SimuMeas

19

20

21

22

23

24

25

Gai

n (d

B)

375 380 385 390370Frequency (GHz)



Data Availability




Acknowledgments


References





































RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia



40

30

20

10

0

Conventional t=2mm

t=4mmt=6mm

Retu

rn lo

ss (d

B)

365 370 375 380 385 390360Frequency (GHz)

(a)

Conventional t=4mm

minus50

0

50

100

Re(Z

) (O

hm)

365 370 375 380 385 390360Frequency (GHz)

(b)

Conventional t=4mm

minus100

minus50

0

50

100

Im(Z

) (O

hm)

365 370 375 380 385 390360Frequency (GHz)

(c)










D0

Z1

Z2

Z3

Z4

(a) (b) (c) (d)x

y


(a)(b)

(c)(d)

40

30

20

10

0

Retu

rn lo

ss (d

B)




997888119864 = 1198640 (119895120572997888119886 119909 + 997888119886 119910) (1a)

997888119864 = 1198640 (minus119895120572997888119886 119909 + 997888119886 119910) (1b)


119873

sum119899=1

119886119899997888119864119899119890119895(2120587120582)119909119899 sin(120579119886minus1205791015840

119886) (2)


sum119899=1


1015840119886)] (3)


119886119899 = 119886119873+1minus119899 (4)





Co PolCross Pol


minus50

minus40

minus30

minus20

minus10

0

10

20A

mpl

itude

(dB)

(a)

Co PolCross Pol


minus50

minus40

minus30

minus20

minus10

0

10

20

Am

plitu

de (d

B)

(b)




Phase shifter38GHz

Transmit gain38GHz

Receive gain38GHz

00000 0 7043 271 23400001 -113 6004 2597 222700010 -188 4582 2522 215200100 -365 2437 2345 197501000 -724 -2022 1986 161610000 -1482 -1138 1228 85811111 -3021 7941 -311 -681

X

Y

Z

d

P(r )

2

2+1








Co PolCross Pol

minus50

minus40

minus30

minus20

minus10

0

10

20A

mpl

itude

(dB)


Azimuth (degree)

(a)

Co PolCross Pol

minus50

minus40

minus30

minus20

minus10

0

10

20

Am

plitu

de (d

B)


Elevation (degree)

(b)





(a)

(b)






Meas(P8)Meas(P16)

365 370 375 380 385 390360Frequency (GHz)

50

40

30

20

10

0

Retu

rn lo

ss (d

B)

(a)



35

30

25

20

15

10

5

0

Isol

atio

n (d

B)

365 370 375 380 385 390360Frequency (GHz)

(b)


369GHz3725GHz376GHz

3795GHz383GHz

minus30

minus20

minus10

0

Am

plitu

de (d

B)


(a)

369GHz3725GHz376GHz

3795GHz383GHz

minus30

minus20

minus10

0A

mpl

itude

(dB)


(b)


369GHz3725GHz376GHz

3795GHz383GHz

minus30

minus20

minus10

0

Am

plitu

de (d

B)


(a)

369GHz3725GHz376GHz

3795GHz383GHz

minus30

minus20

minus10

0

Am

plitu

de (d

B)


(b)



-20deg-10deg0deg

10deg20deg

minus30

minus20

minus10

0A

mpl

itude

(dB)


(a)

-40deg-20deg0deg

20deg40deg

minus30

minus20

minus10

0

Am

plitu

de (d

B)


(b)


-20deg-10deg0deg

10deg20deg

minus30

minus20

minus10

0

Am

plitu

de (d

B)


(a)

-40deg-20deg0deg

20deg40deg

minus30

minus20

minus10

0A

mpl

itude

(dB)


(b)





4 Conclusion



376GHz

minus50

minus40

minus30

minus20

minus10

0Cr

oss-

pola

rizat

ion

ampl

itude

(dB)


(a)376GHz

minus50

minus40

minus30

minus20

minus10

0


Cros

s-po

lariz

atio

n am

plitu

de (d

B)

(b)


SimuMeas

19

20

21

22

23

24

25

Gai

n (d

B)

375 380 385 390370Frequency (GHz)



Data Availability




Acknowledgments


References





































RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia



D0

Z1

Z2

Z3

Z4

(a) (b) (c) (d)x

y


(a)(b)

(c)(d)

40

30

20

10

0

Retu

rn lo

ss (d

B)




997888119864 = 1198640 (119895120572997888119886 119909 + 997888119886 119910) (1a)

997888119864 = 1198640 (minus119895120572997888119886 119909 + 997888119886 119910) (1b)


119873

sum119899=1

119886119899997888119864119899119890119895(2120587120582)119909119899 sin(120579119886minus1205791015840

119886) (2)


sum119899=1


1015840119886)] (3)


119886119899 = 119886119873+1minus119899 (4)





Co PolCross Pol


minus50

minus40

minus30

minus20

minus10

0

10

20A

mpl

itude

(dB)

(a)

Co PolCross Pol


minus50

minus40

minus30

minus20

minus10

0

10

20

Am

plitu

de (d

B)

(b)




Phase shifter38GHz

Transmit gain38GHz

Receive gain38GHz

00000 0 7043 271 23400001 -113 6004 2597 222700010 -188 4582 2522 215200100 -365 2437 2345 197501000 -724 -2022 1986 161610000 -1482 -1138 1228 85811111 -3021 7941 -311 -681

X

Y

Z

d

P(r )

2

2+1








Co PolCross Pol

minus50

minus40

minus30

minus20

minus10

0

10

20A

mpl

itude

(dB)


Azimuth (degree)

(a)

Co PolCross Pol

minus50

minus40

minus30

minus20

minus10

0

10

20

Am

plitu

de (d

B)


Elevation (degree)

(b)





(a)

(b)






Meas(P8)Meas(P16)

365 370 375 380 385 390360Frequency (GHz)

50

40

30

20

10

0

Retu

rn lo

ss (d

B)

(a)



35

30

25

20

15

10

5

0

Isol

atio

n (d

B)

365 370 375 380 385 390360Frequency (GHz)

(b)


369GHz3725GHz376GHz

3795GHz383GHz

minus30

minus20

minus10

0

Am

plitu

de (d

B)


(a)

369GHz3725GHz376GHz

3795GHz383GHz

minus30

minus20

minus10

0A

mpl

itude

(dB)


(b)


369GHz3725GHz376GHz

3795GHz383GHz

minus30

minus20

minus10

0

Am

plitu

de (d

B)


(a)

369GHz3725GHz376GHz

3795GHz383GHz

minus30

minus20

minus10

0

Am

plitu

de (d

B)


(b)



-20deg-10deg0deg

10deg20deg

minus30

minus20

minus10

0A

mpl

itude

(dB)


(a)

-40deg-20deg0deg

20deg40deg

minus30

minus20

minus10

0

Am

plitu

de (d

B)


(b)


-20deg-10deg0deg

10deg20deg

minus30

minus20

minus10

0

Am

plitu

de (d

B)


(a)

-40deg-20deg0deg

20deg40deg

minus30

minus20

minus10

0A

mpl

itude

(dB)


(b)





4 Conclusion



376GHz

minus50

minus40

minus30

minus20

minus10

0Cr

oss-

pola

rizat

ion

ampl

itude

(dB)


(a)376GHz

minus50

minus40

minus30

minus20

minus10

0


Cros

s-po

lariz

atio

n am

plitu

de (d

B)

(b)


SimuMeas

19

20

21

22

23

24

25

Gai

n (d

B)

375 380 385 390370Frequency (GHz)



Data Availability




Acknowledgments


References





































RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia



Co PolCross Pol


minus50

minus40

minus30

minus20

minus10

0

10

20A

mpl

itude

(dB)

(a)

Co PolCross Pol


minus50

minus40

minus30

minus20

minus10

0

10

20

Am

plitu

de (d

B)

(b)




Phase shifter38GHz

Transmit gain38GHz

Receive gain38GHz

00000 0 7043 271 23400001 -113 6004 2597 222700010 -188 4582 2522 215200100 -365 2437 2345 197501000 -724 -2022 1986 161610000 -1482 -1138 1228 85811111 -3021 7941 -311 -681

X

Y

Z

d

P(r )

2

2+1








Co PolCross Pol

minus50

minus40

minus30

minus20

minus10

0

10

20A

mpl

itude

(dB)


Azimuth (degree)

(a)

Co PolCross Pol

minus50

minus40

minus30

minus20

minus10

0

10

20

Am

plitu

de (d

B)


Elevation (degree)

(b)





(a)

(b)






Meas(P8)Meas(P16)

365 370 375 380 385 390360Frequency (GHz)

50

40

30

20

10

0

Retu

rn lo

ss (d

B)

(a)



35

30

25

20

15

10

5

0

Isol

atio

n (d

B)

365 370 375 380 385 390360Frequency (GHz)

(b)


369GHz3725GHz376GHz

3795GHz383GHz

minus30

minus20

minus10

0

Am

plitu

de (d

B)


(a)

369GHz3725GHz376GHz

3795GHz383GHz

minus30

minus20

minus10

0A

mpl

itude

(dB)


(b)


369GHz3725GHz376GHz

3795GHz383GHz

minus30

minus20

minus10

0

Am

plitu

de (d

B)


(a)

369GHz3725GHz376GHz

3795GHz383GHz

minus30

minus20

minus10

0

Am

plitu

de (d

B)


(b)



-20deg-10deg0deg

10deg20deg

minus30

minus20

minus10

0A

mpl

itude

(dB)


(a)

-40deg-20deg0deg

20deg40deg

minus30

minus20

minus10

0

Am

plitu

de (d

B)


(b)


-20deg-10deg0deg

10deg20deg

minus30

minus20

minus10

0

Am

plitu

de (d

B)


(a)

-40deg-20deg0deg

20deg40deg

minus30

minus20

minus10

0A

mpl

itude

(dB)


(b)





4 Conclusion



376GHz

minus50

minus40

minus30

minus20

minus10

0Cr

oss-

pola

rizat

ion

ampl

itude

(dB)


(a)376GHz

minus50

minus40

minus30

minus20

minus10

0


Cros

s-po

lariz

atio

n am

plitu

de (d

B)

(b)


SimuMeas

19

20

21

22

23

24

25

Gai

n (d

B)

375 380 385 390370Frequency (GHz)



Data Availability




Acknowledgments


References





































RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia



Co PolCross Pol

minus50

minus40

minus30

minus20

minus10

0

10

20A

mpl

itude

(dB)


Azimuth (degree)

(a)

Co PolCross Pol

minus50

minus40

minus30

minus20

minus10

0

10

20

Am

plitu

de (d

B)


Elevation (degree)

(b)





(a)

(b)






Meas(P8)Meas(P16)

365 370 375 380 385 390360Frequency (GHz)

50

40

30

20

10

0

Retu

rn lo

ss (d

B)

(a)



35

30

25

20

15

10

5

0

Isol

atio

n (d

B)

365 370 375 380 385 390360Frequency (GHz)

(b)


369GHz3725GHz376GHz

3795GHz383GHz

minus30

minus20

minus10

0

Am

plitu

de (d

B)


(a)

369GHz3725GHz376GHz

3795GHz383GHz

minus30

minus20

minus10

0A

mpl

itude

(dB)


(b)


369GHz3725GHz376GHz

3795GHz383GHz

minus30

minus20

minus10

0

Am

plitu

de (d

B)


(a)

369GHz3725GHz376GHz

3795GHz383GHz

minus30

minus20

minus10

0

Am

plitu

de (d

B)


(b)



-20deg-10deg0deg

10deg20deg

minus30

minus20

minus10

0A

mpl

itude

(dB)


(a)

-40deg-20deg0deg

20deg40deg

minus30

minus20

minus10

0

Am

plitu

de (d

B)


(b)


-20deg-10deg0deg

10deg20deg

minus30

minus20

minus10

0

Am

plitu

de (d

B)


(a)

-40deg-20deg0deg

20deg40deg

minus30

minus20

minus10

0A

mpl

itude

(dB)


(b)





4 Conclusion



376GHz

minus50

minus40

minus30

minus20

minus10

0Cr

oss-

pola

rizat

ion

ampl

itude

(dB)


(a)376GHz

minus50

minus40

minus30

minus20

minus10

0


Cros

s-po

lariz

atio

n am

plitu

de (d

B)

(b)


SimuMeas

19

20

21

22

23

24

25

Gai

n (d

B)

375 380 385 390370Frequency (GHz)



Data Availability




Acknowledgments


References





































RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia




Meas(P8)Meas(P16)

365 370 375 380 385 390360Frequency (GHz)

50

40

30

20

10

0

Retu

rn lo

ss (d

B)

(a)



35

30

25

20

15

10

5

0

Isol

atio

n (d

B)

365 370 375 380 385 390360Frequency (GHz)

(b)


369GHz3725GHz376GHz

3795GHz383GHz

minus30

minus20

minus10

0

Am

plitu

de (d

B)


(a)

369GHz3725GHz376GHz

3795GHz383GHz

minus30

minus20

minus10

0A

mpl

itude

(dB)


(b)


369GHz3725GHz376GHz

3795GHz383GHz

minus30

minus20

minus10

0

Am

plitu

de (d

B)


(a)

369GHz3725GHz376GHz

3795GHz383GHz

minus30

minus20

minus10

0

Am

plitu

de (d

B)


(b)



-20deg-10deg0deg

10deg20deg

minus30

minus20

minus10

0A

mpl

itude

(dB)


(a)

-40deg-20deg0deg

20deg40deg

minus30

minus20

minus10

0

Am

plitu

de (d

B)


(b)


-20deg-10deg0deg

10deg20deg

minus30

minus20

minus10

0

Am

plitu

de (d

B)


(a)

-40deg-20deg0deg

20deg40deg

minus30

minus20

minus10

0A

mpl

itude

(dB)


(b)





4 Conclusion



376GHz

minus50

minus40

minus30

minus20

minus10

0Cr

oss-

pola

rizat

ion

ampl

itude

(dB)


(a)376GHz

minus50

minus40

minus30

minus20

minus10

0


Cros

s-po

lariz

atio

n am

plitu

de (d

B)

(b)


SimuMeas

19

20

21

22

23

24

25

Gai

n (d

B)

375 380 385 390370Frequency (GHz)



Data Availability




Acknowledgments


References





































RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia



-20deg-10deg0deg

10deg20deg

minus30

minus20

minus10

0A

mpl

itude

(dB)


(a)

-40deg-20deg0deg

20deg40deg

minus30

minus20

minus10

0

Am

plitu

de (d

B)


(b)


-20deg-10deg0deg

10deg20deg

minus30

minus20

minus10

0

Am

plitu

de (d

B)


(a)

-40deg-20deg0deg

20deg40deg

minus30

minus20

minus10

0A

mpl

itude

(dB)


(b)





4 Conclusion



376GHz

minus50

minus40

minus30

minus20

minus10

0Cr

oss-

pola

rizat

ion

ampl

itude

(dB)


(a)376GHz

minus50

minus40

minus30

minus20

minus10

0


Cros

s-po

lariz

atio

n am

plitu

de (d

B)

(b)


SimuMeas

19

20

21

22

23

24

25

Gai

n (d

B)

375 380 385 390370Frequency (GHz)



Data Availability




Acknowledgments


References





































RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia



376GHz

minus50

minus40

minus30

minus20

minus10

0Cr

oss-

pola

rizat

ion

ampl

itude

(dB)


(a)376GHz

minus50

minus40

minus30

minus20

minus10

0


Cros

s-po

lariz

atio

n am

plitu

de (d

B)

(b)


SimuMeas

19

20

21

22

23

24

25

Gai

n (d

B)

375 380 385 390370Frequency (GHz)



Data Availability




Acknowledgments


References





































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




RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia


Documents

Design of Series-Fed Bandwidth-Enhanced Microstrip Antenna …downloads.hindawi.com/journals/ijap/2019/3857964.pdf · 2019. 7. 30. · ResearchArticle Design of Series-Fed Bandwidth-Enhanced