Design of a Rectangular Microstrip Patch Antenna for GNSS/GPS System

Design of a Rectangular Microstrip Patch Antenna for GNSS/GPS System

Kishor Chandra Arya1, Bimal Bhatt2, Saurabh Adhikari3, Rachna Arya4

1,2,3M. Tech Scholar, 4Assistant Professor Department of Electronics & Communication Bipin Tripathi Kumaon Institute of Technology Dwarahat, Uttarakhand (India) 263653

Abstract – This paper deals with the design of a rectangular microstrip patch antenna for GNSS/GPS network. The proposed antenna has symmetrical properties and has been designed on Rogers TMM4 substrate with corporate feed input. It radiates at L2 (1227.6MHz) frequency band. The performance of the antenna is measured in terms of Return loss, VSWR, Gain, frequency of operation and radiation pattern. The return loss S11, Gain and radiation pattern of the fabricated antenna was simulated using Ansoft HFSS, which is a good agreement with experimental data.

Keywords GNSS, Microstrip patch, probe feed, Return loss(S11), VSWR.

1. INTRODUCTION

   The Global Navigation Satellite System (GNSS) is a constellation of satellites, transmitting signals for use in navigation and positioning applications, anywhere on the surface of the earth. There are currently two Global Navigation Satellite Systems in operation: the U.S. Global Positioning System (GPS) and the Russian Global Navigation Satellite System (GLONASS). A third system, Galileo, is currently under development in Europe.

   Global Navigation Satellite System (GNSS) support applications where high accuracy is required such as precision agriculture, tsunami, surveying, land management and offshore operation. Such techniques are especially sensitive to ionospheric perturbation. The aim of this project is to mitigate the impact of ionospheric disturbances on high accuracy GNSS positioning technique.

   Fig 1- Structure of the rectangular microstrip patch antenna

   In this paper a rectangular microstrip antenna is designed at L2 frequency, suitable for use in space monitoring applications.

2. ANTENNA CONFIGURATION

   The antenna is simulated on Rogers TMM4 substrate with a dielectric constant of 4.5, the thickness of substrate is 1.59mm. The length and width of the antenna can be calculated by transmission line method as given below Width of antenna is given by

   Investigation of fenn (2008) shows that an antenna array with adaptive direction beam is a promising method to detect, using GPS/GNSS signal, some disturbances in the ionosphere. Due to increased radiation pattern and high gain such antennas are able to mitigate the impact of ionospheric disturbances.

   W =

   2

   2. +1

   The effective dielectric constant

   reff

   (1)

   The GPS satellite transmit low power radio signal on multiple frequencies. L1 and L2 are the two basic carrier

   + 1 1

   =

   2 2

   frequencies that contain the navigational signal. The L1 frequency is 1575.42MHzin the UHF band while the L2 frequency is 1227.6 MHz.

   The extension length is given by

   reff + 0.3 W + 0.264

   h

   L = 0.412*h*

   h

   reff 0.258 ) (

   W + 0.8

   (3)

   The effective length is given by

   L

   (4)

   eff=2.

   Therefore the actual length of the patch is calculated by L = Leff -2 L (5)

   By substuting the value of operating frequency L2 =

   1227.6MHZ, c = 3×108m/s, r = 4.5 and h = 1.59mm the width of the patch (W) becomes 73.68 mm and Leff= 56.3mm, substituting eff= 4.71 and the values of W and h, we get L = 0.73 mm. In final, we obtain the length of the patch using this equation.

   L = Leff – 2L (6)

   L = 56.3 mm 1.46 mm = 54.83 mm.

   The transmission line model is applicable to infinite ground planes only. However, for practical considerations, it is essential to have a finite ground plane. Similar results for

   Fig 2 Designed rectangular microstrip patch antenna

   finite and infinite ground plane can be obtained if the size of the ground plane is greater than the patch dimensions by approximately six times the substrate thickness all around the periphery. Hence, for this design, the ground plane dimensions would be given as:

   L(g) = 6h + L (7)

   L (g) = 6*(1.59mm) + 54.83mm= 64.37mm

   W(g) = 6h + W (8)

   W (g)= 6*(1.59mm) + 73.68mm = 83.22mm

   Hence after calculating all the parameters using the above formulae,the rectangular microstrip patch antenna was designed.

   Ansoft LLC

   62.50

   50.00

   Name

   X

   Y

   dB(VSWR(1))

   37.50

   25.00

   12.50

   XY Plot 2

   HFSSDesign1 ANSOFT

   WR(1))

   o

   urve In

   C f

   1.8470

   1.2560

   m1

   ep1

   dB(VS Setup1 : Sw e

   Table 1- Antenna dimensions

   Frequency	1227.6MHz
   Height	1.59mm
   Dielectric constant	4.5
   Width of patch (W)	73.68mm
   reff	4.71
   Extention length( L)	0.73mm
   Length of patch(L)	54.83mm
   Return loss(S11)	-19.50db
   VSWR	1.84
   Gain	6.51%

   0.00

   m1

   1.00 1.10 1.20 1.30 1.40 1.50

   Freq [GHz]

   Fig 3 VSWR diagram of L2 rectangular patch

   However in order to achieve 50 match a little trial and error is used and the optimized feed locations are found to beXf= 36.84mm and Yf= 24.63mm. In the present investigation, it was found, at the L2 frequency, that the VSWR 2 (1.84) which shows that the printed square patch antenna is better matched to its feeding strip line.

3. SIMULATION RESULTS

   Figure 2 below shows the designed RMSA with W = 73.68mm and L=54.83mm and ground plane dimensions as. Lg = 64.37mm and Wg = 83.22mm. Probe feed has been used to feed the antenna as in figure below. The optimized feed location are calculated using,

   Ansoft LLC

   0.00

   -2.50

   Y

   X

   me

   N

   -5.00 a

   m1 1

   .2560 –

   19.5000

   dB(S(1,1))

   -7.50

   -10.00

   XY Plot 1

   HFSSDesign1 ANSOFT

   Cur

   ve Info

   dB(S(1,1

   ))

   Setup1

   : Sw ee

   p1

   Y =

   = 12.63mm(9)

   -12.50

   f 2

   X == 36.84mm(10)

   -15.00

   f 2

   -17.50

   -20.00

   m1

   1.00 1.10 1.20 1.30 1.40 1.50

   Freq [GHz]

   Fig 4 – S11 diagram of L2 rectangular patch

   Fig 4 shows the value of S11 which is equal to 19.50 dB and the bandwidth of the antenna is 6.51% compatible with the intended application. Figure 5 shows the electric field distribution, it can be seen thatthe electric field distribution is maximum at the width of the patch as its the radiating edge.

   Ansoft LLC

   Name	Theta	Ang	Mag
   m1	0.0000	0.0000	12.8583

   -90

   -60

   -120

   -30

   -150

   Radiation Pattern 2

   0

   m1

   8.00

   1.00

   -6.00

   -13.00

   -180

   30

   150

   60

   90

   120

   HFSSDesign1 ANSOFT

   Curve Info

   dB(rETotal) Setup1 : LastAdaptive Freq='1.2276GHz' Phi='0deg'

   dB(rETotal) Setup1 : LastAdaptive Freq='1.2276GHz' Phi='90deg'

   Fig 7 Radiation pattern of rectangular patch antenna

4. CONCLUSION

   Fig 5 Electric field distribution

   Fig 6 shows the gain and radiation pattern of the designed rectangular patch antenna and it was found that the antenna give a suitable radiation pattern in desired direction and the gain is equal to 5.37db.

   From the simulation analysis of the proposed antenna it can be easily observed that designed rectangular antenna can operate in the L2 frequency band, having return loss S11is 19.50db, Gain is 5.37dband bandwidth 6.5% compatible with intended applications. It is also observed that the antenna offers improved characteristics of matching and radiation at L2 frequency and its general performance is within acceptable range. Further, the VSWR of the fabricated antenna is 2 which is well within acceptable margins.The present network thus proposed with high gain, low cost and small footprint meets our goal.

   Ansoft LLC

   Name	Theta	Ang	Mag
   m1	2.0000	2.0000	5.3783

   -90

   -60

   -120

   -30

   -150

   Radiation Pattern 1

   0

   m1

   2.00

   -6.00

   -14.00

   -22.00

   -180

   30

   150

   60

   90

   120

   HFSSDesign1 ANSOFT

   Curve Info

   dB(GainTotal) Setup1 : LastAdaptive Freq='1.2276GHz' Phi='0deg'

   dB(GainTotal) Setup1 : LastAdaptive Freq='1.2276GHz' Phi='90deg'

5. REFRENCES

1. Yashu Rajput, Tejender Singh Rawat and LeenaVarshney, CPW Feed Patch Antenna for GPS Applications International Journal Of Computational Engineering Research (ijceronline.com), Vol. 2, Issue. 6

2. Xi Li, Lin Yang, and Min Wang, New design of compact shorted annular stacked patch antenna for Global Navigation Satellite System application Progress In Electromagnetics Research C, Vol. 36, 223-232, 2013

3. Xi Li, Lin Yang, Min Wang, Yi Wang, Xi Chen, and Juan Lei, Wideband shorted annular stacked patch antenna for Global Navigation Satellite System application with compact size and broad beamwidth characteristics Progress In Electromagnetics Research C, Vol. 35, 123-134, 2013

4. H. Hamoudi, B. Haddad, P. Lognonne, Dual frequency GPS antenna for space monitoring ICTRS 2014, ISBN- 978-989-758- 033-8

5. W. Lechner and S. Baumann, "Global Navigation Satellite Systems,"Computers and Electronics in Agriculture., 25, pp. 67

   Fig 6 Gain pattern of rectangular patch antenna

   85, 2000.

6. K. Borre, D.M. Akos, N.Bertelsen, P. Rinder and S.H. Jensen, A software-defined GPS and GALILEO receiver : A single frequencyapproach, Birkhauser, 2007.