A design procedure for active rectangular microstrip patch antenna

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  • 1. INTERNATIONAL JOURNAL OF ELECTRONICS ANDInternational Journal of Electronics and Communication Engineering & Technology (IJECET), ISSNCOMMUNICATION–ENGINEERING Issue 1, January- June (2012), (IJECET)0976 – 6464(Print), ISSN 0976 6472(Online) Volume 3, & TECHNOLOGY © IAEMEISSN 0976 – 6464(Print)ISSN 0976 – 6472(Online)Volume 3, Issue 1, January- June (2012), pp. 123-129 IJECET© IAEME: www.iaeme.com/ijecet.htmlJournal Impact Factor (2011): 0.8500 (Calculated by GISI) ©IAEMEwww.jifactor.com A DESIGN PROCEDURE FOR ACTIVE RECTANGULAR MICROSTRIP PATCH ANTENNA 1 Mahmoud Abdipour, Gholamreza Moradi, Reza Sarraf Shirazi 2 2 1 Department of Electrical Engineering, Azad Branch, Islamic Azad University,Arak,Iran (Mahmoud.abdipour@gmail.com) 2 Department of Electrical Engineering,Amirkabir University,Tehran, Iran (ghmoradi@aut.ac.ir) 2 Department of Electrical Engineering,Amirkabir University,Tehran,Iran (sarraf@aut.ac.ir)ABSTRACT In this paper a design procedure for active rectangular microstrip patchantenna is presented. The design procedure begins with the theory of passivepart. Then appropriate input and output matching circuits are examined. Finally,with connecting passive antenna as amplifier input, the overall structure isdesigned and simulated. Also a comparison between passive and active antennais done. The used substrate is RT/DOUROID 5880 with relative permittivity of2.2 and thickness of 1.588 mm .The ADS software and its full wave Momentumis used for simulation. The results show a relative improvement in the activeantenna characteristics with respect to passive antenna.Keywords- Microstrip antenna, Active antenna , X-band, ADS 2009 1. INTRODUCTION In recent years, active antenna has been welcomed because of their vastadvantages. In fact, using this structure in addition to the advantages of passiveantenna, can be overcome the disadvantages of these antenna such as smallbandwidth, large noise figure and large length [1]. In active antenna structure, apassive antenna is placed beside of amplifier. If the antenna to be used as a loadto the amplifier, and if antenna to be used as an input to the amplifier, antennais transmitter and receiver, respectively. Important considerations in the designof active antenna include high gain and smooth in all its bandwidth, low noise 123
  • 2. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 3, Issue 1, January- June (2012), © IAEMEfigure, appropriate matching in input and output, linear operation and the smallsize. Among antennas that are used as passive part for such structures,rectangular microstrip patch antenna are the most popular because of ease ofanalysis and fabrication, and their attractive radiation characteristics[2]. Feedtype, plays an important role in the design of patch antenna. an microstrip patchantenna can be feed with coaxial probe or microstrip line that in the meanwhilemicrostrip line is preferable because this line can be considered to continue ofpatch which help to better and easier input/output matching. Since the inputimpedance of a patch is often large, we usually use inset-fed method for inputimpedance matching with the line characteristic impedance. In this methodhow much we move from the edge toward the patch center, patch impedance isreduced, so that in patch center is equal to zero[3].2. PATCH ANTENNA DESIGN Fig.1 shows the patch geometry of an inset-fed rectangular patch. Basicparameters include length of patch( L ) , width of patch ( W ) , the notch width p p(g), the inset distance from the radiating edge(d) and width of feed line (w).Approximate equations related on the rectangular antenna analysis and designcan be calculated as follows:The width of the antenna can be determined by [4]: vo 2 WP = 2 fr εr +1 (1)The effective dielectric constant is given by [5],[6]: −1/2 εr +1 εr −1  h  ε ref f = + 1 + 12  for W p / h > 1 2 2 (2)  Wp  Normalized extension of the length, ∆L, which is due to open endedtransmission line can be obtained by [7]:  Wp  (ε ref f + 0.3)  + 0.264  ∆L = 0.412  h  h  Wp  (3) (ε ref f − 0.258 )  + 0.8   h The actual length of the patch, Lp , can be expressed by [3]: νo Lp = − 2∆L 2 f r ε reff (4)The notch width, g, can be obtained by using [8]: νo 4.6 × 10 − 14 f fr = + 2 × ε ref f g 1.01 (5) νo 4.65 × 10−12 g= 2 × ε ref f f (6)In this equations, is resonant frequency and f is operating frequency.We can calculate the value of Z as: 0 124
  • 3. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 3, Issue 1, January- June (2012), © IAEME π  Z o = Rin cos 2  d  L   p  (7)Where, d , is the inset distance from the radiating edge, and Rin is the resonantinput resistance when the patch is fed at a radiating edge.We can calculate R as [9]: in 1 Rin = 2 ( G1 + G12 ) (8)Where, G1 , is the conductance of a single slot and can be obtained by: 2   koW p   sin  π Cos θ   1   2   sin 3 θ dθ 120 π 2 ∫  G1 =  0  cos θ  (9)    and , G , is the mutual conductance and can be calculated using: 12 2   koW p   sin  π Cos θ   1   2   J k L sin θ sin 3 θ dθ 120 π 2 ∫   o( o p G12 = cos θ ) 0       (10)J0 , is the Bessel function of the first kind of order zero. Fig.1 Geometry of a microstrip patch antenna Also the width of feed line assuming ZC = Z 0 can be calculated using [1]: 120π ZC = (11) W W  ε reff  h + 1.393 + 0.667 ln  h + 1.444      The final values are determined through extensive numerical simulations. 2. AMPLIFIER DESIGN Application is an essential factor in amplifier part design of an activeantenna. For example, for transmitter applications, the design goals are toachieve higher gain and more bandwidth. For reception applications, problemabout noise figure is design goal. This is a criterion for transistor selection, sothat for transmitter antenna, HBT transistors are preferred because of their highgain. Whereas for reception application, HEMT transistors are good choicesbecause of their low noise. 125
  • 4. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 3, Issue 1, January- June (2012), © IAEME Various stage of amplifier design for the active antenna is shown in thefollowing flow diagram. Fig.2 Amplifier design flow diagramThe final stage is integration amplifier part with the passive antenna.4. DESIGN EXAMPLE In this section, an active microstrip patch antenna is designed and we willreview the effect of using active part beside a passive antenna. Designing isdone for X-band with 10 GHz center frequency. The substrate is RT/DUROID5880 that its characteristics are given in Table.1. Table 1 RT/DUROID 5880 characteristics Substrate εr h, mm T,mm RT/DUROID 2.2 1.588 0.035 5880 ADS software is used to simulate. Using equation [1]-[11], we can calculatethe physical dimensions of microstrip patch antenna as shown in Table.2. 126
  • 5. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 3, Issue 1, January- June (2012), © IAEME Table 2 The physical dimensions of microstrip patch antenna Length of the patch,LP, in mm 9.6 Width of the patch,WP, in mm 11.86 Position of inset fed point,d,in mm 2.5 Width of the microstrip feed 2 line,W,in mm Notch width,g,in mm 0.2 The simulation results of the designed patch are given in Fig.3.As shown inthis figure, the antenna has a good matching performance. 200 0 m1 indep(m1)= 1.000E10 plot_vs(real(Zin), freq)=49.374 -5 150 dB(S(1,1)) -10 real(Zin) 100 m2 -15 freq=10.05GHz m1 dB(S(1,1))=-22.399 50 -20 m2 0 -25 8.0 8.5 9.0 9.5 10.0 10.5 11.0 11.5 12.0 8.0 8.5 9.0 9.5 10.0 10.5 11.0 11.5 12.0 freq, GHz freq, GHz (a) (b) Fig.3 The simulation results (a) The Input Impedance (b) The S11 .Using given flow diagram for the design of the amplifier and connect to thepassive part and overall circuit layout extraction we reach to following strucure . Fig 4 Final layout of receiver active antenna 127
  • 6. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 3, Issue 1, January- June (2012), © IAEME Simulation results are shown in the following 0.665 1.330 1.325 0.660 m2 m1 freq=10.00GHz freq=10.00GHz nf(2)=0.650 1.320 VSWR2=1.312 0.655 m2 VSWR2 nf(2) 1.315 m1 0.650 1.310 0.645 1.305 0.640 1.300 0.635 1.295 9.90 9.92 9.94 9.96 9.98 10.00 10.02 10.04 10.06 10.08 10.10 9.90 9.92 9.94 9.96 9.98 10.00 10.02 10.04 10.06 10.08 10.10 freq, GHz freq, GHz (a) (b) 1.8 12 m3 m4 1.7 freq=10.00GHz VSWR1=1.391 9 1.6 VSWR1 dB(S(2,1)) 6 1.5 3 m3 m4 1.4 freq=10.00GHz dB(S(2,1))=11.132 0 1.3 9.90 9.92 9.94 9.96 9.98 10.00 10.02 10.04 10.06 10.08 10.10 9.90 9.92 9.94 9.96 9.98 10.00 10.02 10.04 10.06 10.08 10.10 freq, GHz freq, GHz (c) (d) Fig.5 Results of active antenna simulation (a) VSWRout (b) NFout (c) The S21 (d) VSWRin A comparison between active and passive antennas is shown in Table.3. Table 3 A comparison between active and passive antennas Characteristic Preferable Antenna Structure Simplicity Passive Antenna Design Simplicity Passive Antenna Reliability Passive Antenna Pattern Characteristic Similar EIRP & Output Power Active Antenna Bandwidth Active Antenna Gain Active Antenna Noise Figure Active Antenna5. CONCLUSION In this paper a procedure of designing active microstrip patch antenna waspresented. Also an X-band active antenna is designed. Finally a comparisonbetween passive and active structure is examined. 128
  • 7. International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 3, Issue 1, January- June (2012), © IAEMEREFERENCES[1]Garg. R,Bahl.I,Ittipiboon.AJ, “Microstrip Antenna design handbook”, ArtchHouse,Boston.London.[2] Balanis. C.A(1997), “Antenna theory: Analysis and Design,” New York,John Wiley & Sons Inc.[3] Basilio . L.I, et.al.(2001), “The Dependence of the input impedance onFeed position of probe and microstrip line-fed patch antenna”, IEEE Trans.Antenna & propagation, Vol.AP(49):45-47.[4] James .J.R and Hall .P.S(1989),“Handbook of microstrip antennas,”PeterPeregrinus, London,UK.[5] Pozar,D.M., and Schaubert .D.H(1995),“Microstrip Antennas, the Analysisand Design of microstrip Antennas and Arrays” IEEE Press, New York, USA.[6] Bahl, I.J and Bhartia .P(1980), “ Microstrip Antenna Technology,” ArtchHouse, Dedham, MA.[7] Owens .R.P(1976), “Accurate Analytical Determination of quasistaticMicrostrip Line Parameters”, The Radio and Electronic Engineer, 46 (7):360-364.[8] Matin, M.A and Sayeed A.I(2010), “A Design Rule for Inset-FedRectangular Microstrip Patch Antenna,”WSEAS TRANSACTION oncommunications;1 (9).[9] Derneryd, A.G(1978), “A theoretical Investigation of the RectangularMicrostrip Patch Antenna Element,” IEEE Trans. Antennas andPropation,26(4): 532-535. 129