Designof 1x4, PolarizationMicrostrip ArrayAntenna of 1x2, 1x4, and 2x2 Dual.pdf · Figure 1: Layoutofthe 450 polarized single patchantenna For this project, a parallel or corporate
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Proceedings of IEEE 2008 6th National Conference on Telecommunication Technologies andIEEE 2008 2nd Malaysia Conference on Photonics, 26-27 August 2008, Putrajaya, Malaysia
Design of 1x2, 1x4, and 2x2 DualPolarization Microstrip Array Antenna
M. S. R. Mohd Shah, M. K. Suaidi', M. Z. A. AbdulAziz', M.R Che Rose', M. F Abd. Kadir', A. S. Ja'afar',
M.K.A. Rahim2
'Faculty of Electronic and Computer EngineeringUniversiti Teknikal Malaysia Melaka,
Hang Tuah Jaya, Ayer keroh, 75450, Melaka, Malaysia
M.K.A. Rahim2
2Faculty of Electrical EngineeringUniversiti Teknologi Malaysia,
Abstract - This paper present 3 design of array antennafrom type of inset-fed microstrip patch antenna oriented at 450and -450. The antenna is capable to generate dual-polarizationradiation pattern slanted at 450 and -450. Combinations of twoand more patches using quarter-wave impedance matchingtechnique have been used to design the array antenna operate at2.4 GHz. The design were simulated using Microwave Office2006 and were fabricated on FR4 substrate with a dielectricconstant Er =4.7, tan 6 =0.019 and thickness =1.6mm. Thesimulation and measurement result have been compared. The 3design 1x2, 1x4 and 2x2 array antenna yields a bandwidth of 5%,return loss <-10dB, HPBW for single element found at 90.07°-89.750 and HPBW for array antenna found at 84.68°-79.05°.Simulations and measurements were shown that the arrayantennas gave better results in term of VSWR, return loss andantenna gain compared to the single patch. The higher number ofpatches in an array will improve the performance of the antenna.
In microstip antenna designs, there have been interests in thedual-polarization operation, which increase requirement ofpolarization diversity in wireless communication. A dual-polarized microstrip antenna can be realized by feeding therectangular microstrip patch at two orthogonal edges, throughedge feed or probe feed, which excites TM01-and TM10-modewith orthogonal polarizations [1]-[4]. Both the element itselfand its array often achieve isolation of about -20dB [1]-[3].The most reported technique for achieving dualpolarization is using different feed mechanisms such asaperture-coupling a single patch with crossed narrow slots ortwo offset narrow slots [5]. This technique requires arelatively complicated feed arrangement [6] or a complexmultiplayer construction [7] to reduce the coupling betweenthe two feed lines and therefore adds complexity to thefabrication process.
Dual-polarized microstrip antenna fed by slotcoupling is first reported by Adrian and Schaubert [8]. Dualoffset slots are used in [8], and it achieves isolation of -18dB.This dual-polarized antenna offers additional advantages ofeasy integration with active RF/microwave circuits, whichwould be useful for active arrays applications.
In this paper, the design of inset fed microstripantenna is proposed at 45° and -45° to achieve the optimumperformance of the return loss, VSWR, antenna gains andbroadband microstrip array antenna in which the gain andbandwidth can improved by using combination more patch ofcorporate feeding. The patterns were considered to be constantalong W and varied sinusoidal with L. Details of the designedbroadband dual-polarized microstrip antennas is proposed byusing the inset feed technique [9].
II. DESIGN PROCEDURE
A prototype antenna is then designed, andexperimental results are presented. There were several ways todesign microstrip antennas such as transmission line, cavityand full wave models. For simplicity purpose, transmissionline model was used in this project. Dimensions of the antennaare depending on the operating frequency and dielectricconstant of the substrate. The parametric study on the singlepatch antenna is done first to understand the characteristics ofthe antenna. Figure 1 showed the dimension of the 45° patchantenna was simulated using Microwave Office 2006.
The important parameters for rectangular patchantennas are dielectric constant and area. The effectivedielectric constant is very important in order to calculatefringing effect and wave propagations. The area of the patch isdepending on resonant frequency. This paper is focusing onthe combination of the same antenna to obtain a betterresponse by developing the arrays.
Figure 1: Layout of the 450 polarized single patch antenna
For this project, a parallel or corporate feedconfiguration was used to build up the array. In parallel feed,the patch elements were fed in parallel by using transmissionlines. The transmission lines were divided into two branchesaccording to the number of patch elements. The quarter-wavetransformer impedance matching technique was applied todivide the power uniformly to all patches.
The impedances of the line were translated intolength and width by using Microwave Office 2006. Thedimensions of the transmission line were shown in Table 1.Figure 2 show the circuit layout of lx2 array antennas. Thisdesign can produce better high gain and broadband comparedsingle element. The position of the patch antenna is oriented at450 and -45° to obtain dual- polarized radiation.
The design of 2x2 and lx4 array antennas also hasbeen investigated. Figure 3 and Figure 4 shown the design oflx4 and 2x2 array antenna. In both design, the improvementof return loss, VSWR, and antenna gain was investigated. Thefeeding type of 2x2 array antenna is using coax probe.Whereas, the lx2 and lx4 array antenna are usingtransmission line feeding technique.
Table 1: Dimension of line impedances
Figure 2: Layout of the 450 and -45 dual-polarized lx2 array antenna
Figure 3: Layout of the 450 and -45 'dual-polarizedlx4 array.
Figure 4: Layout of the 450 and -45 dual-polarized2x2 array.
III. RESULT DISCUSSION
After all dimensions have been calculated, the designwould then be simulated in Microwave Office 2006 softwareto obtain the return loss, radiation pattern, and VWSR. Thesingle patch produced return loss and VSWR of -16.29 dB and1.366. The simulation and measurement of this single elementare 3.7°O and 3.5°O
Radiation Pattern for 1 x2 Dual-Polarized Array Antenna
1-20 -10 -0-5 5 0 5 0
0-6
0O4
Theta(Degree)E-Plane
----H-Plan.
Figure 5: Radiation Pattern for lx2 Dual-Polarized Array Antenna
Figure 6: Radiation Pattern for lx4 Dual-Polarized Array Antenna
114
Impedance (Q) Length (mm) Width (mm)
50 16.5671 2.87872
70.71 17.0633 1.4839
100 17.5478 0.614685
Radiation Pattern for 1x4 Dual-Polarized Array Antenna
-0 2-
-200 -150 -100 -50 o 50 100 150 200
TFheta(Degree)
H-PIanen
Radiation Pattern for 2x2 Dual-Polarized array antenna
0O6
0O4
Theta(Degree)
...... E-Plane
Figure 7: Radiation Pattern for 2x2 Dual-Polarized Array Antenna
Figure 5 show the radiation pattern for 450 and -45°polarizations lx2 array antenna. The result of HPBW (HalfPower Bandwidth) is obtained by taking the value -3dB frommaximum point at radiation pattern. The value of HPBW for450 and -45° polarized single element found at, 0. HPBW forlx2 array antennas found at 84.68°-79.05°. The HPBW istwice the angle with respect to the angle of the maximumdirectivity, where this directivity has rolled off 3 dB withrespect to the maximum directivity. This lx2 array antennaproduced return loss and gain of -17.6 dB and 7.505 dB.
Figure 6 shows the simulation results for 450 and -45°lx4 dual-polarized array antennas with gain and return loss of7.944dB and -21.08 dB respectively at the resonant frequency.The result of return loss and antenna gain for 2x2 arrayantenna is -19.46 dB and 8.734 dB. Again, this proves that thecombination of more patches in the array antenna can improvethe antenna gain. The plots data of return loss for lx2, lx4 and2x2 array antennas are shown in Figure 8.
Figure 8: Return Loss [dB] for 45° and -45° dual-polarized array antenna.
The same parameters involve in the simulation weremeasured using Advantest R3767 CG Network Analyzer. Thereturn loss is below -10 dB within the frequency rangebetween 2.51-2.61 GHz, corresponding to a bandwidth of4.22%. Figure 9 plots the radiation pattern measured at twoprinciple plane for 450 polarized lx2 patch array antenna,respectively.
(a)
/ rf N.IN
~~~~~~~ Nm, j t .
21~~\ M,4. .A
qt- X
L,_ ><~~~~~~~~~~~~~~~~~~
(b)
Figure 9: Measured radiation pattern at both plane lx2patch array antennasa) H-plane b) E-plane
IV. CONCLUSION
A high gain of 3 design microstrip array antennausing inverted feeding line is proposed for MIMO applicationin this paper. The antennas are operated at resonant frequencyaround 2.4GHz with low VSWR. The VSWR and return losshave been observed for single, lx2, lx4 and 2x2 dual-polarized microstrip patches array antennas. It can beconcluded that the responses from the 2x2 and lx4 patcheswere better compared to the lx2 array antenna and singlepatches antenna. Although the results from the measurementwere not exactly same as in the simulation, it was stillacceptable since the percentage error was very small due tothe fabrication process has been done manually.
REFERENCES
[1] K. F. Lee and W. Chen, Eds., Advances in Microstrip Antennas andPrintedAntennas, New York: Wiley, 1997, pp. 163-217.
[2] J. R. James and P. S. Hall, "Handbook of Microstrip Antennas ", Eds.,Peter Peregrinus, UK, 1989.
[3] L. J. Du Toit and J. H. Cloete, "Dual polarized linear microstrip patcharray," in Proc. IEEE Antennas and Propagation Symp. Dig, 1987,pp.810-813.
[4] M. J. Cryan and P. S. Hall, "IntegratedActive Antenna with SimultaneousTransmit-Receive Operation"Electron. Lett, vol. 32, no. 4, pp. 286-287,1996.
[5] Padhi, S.K., Karmakar, N.C., Sr., Law, C.L., and Aditya, S. Sr., "A dual
115
Return Loss of Array Antenna
a
r'r
Freq(GHz)
1x2 Array Antenna1x4 Array Antenna
--- 2x2 Array Antenna
4 4
polarized aperture coupled circular patch antenna using a C-shapedcoupling slot", IEEE Trans. Antennas Propag., 2003, 51, (12), pp. 3295-3298
[6] Lindmark, B., "A novel dual polarized aperture coupled patch elementwith a single layer feed network and high isolation". IEEE AntennasPropagation Society Int. Symp. Dig., Montreal, Que.,Canada, 1997, Vol.4, pp. 2190-2193
[7] Shavit, R., Tzur, Y., and Spirtus, D, "Design of a new dual-frequency anddual-polarization microstrip element", IEEE Trans. Antennas Propag.,2003, 51, (7), pp. 1443-145 1.
[8] A. Adrian and D. H. Schaubert, "Dual aperture-coupled microstrip antennafor dual or circular polarization,"Electron. Lett., vol. 23, pp. 1226-1228,1987.
[9] M. S. R. Mohd Shah, M.R Che Rose, M. F Abdul Kadir, D. Misman,M. Z. A. Abdul Aziz, and M. K Suaidi, "Dual Polarization Inset-FedMicrostrip Patch Antenna", APACE 2007