Design and Optimization of Circularly Polarized Antenna for 2.25GHZ A.Anusuya, Janet stephy ABSTRACT Micro strip patch antenna used in many commercial purposes nowadays. The demand of smaller sized antenna increased rapidly in communication field such as aircrafts, radar communications, marine field, satellite communications, GPS, GSM etc. In order to meet the demand microstrip patch antenna is introduced. It used widely to meet all the requirements of wireless communication. In this paper, circularly polarized antenna is designed for the frequency of 2.25GHz. And the designed antenna is optimized using HFSS software. INTRODUCTION Micro strip antenna was used widely in all communications fields. Microstrip antenna has the advantage of low cost, low profile and ease of installation. Due to its advantage it was used in widely and it has the disadvantage of narrow bandwidth. In microstrip patch antenna different substrate and different feeding technique was used. Based on the different feeding technique and type of substrate parameters of antenna will change. Parameter of antenna includes return loss, bandwidth, gain, radiation pattern, directivity, VSWR etc. Based on these parameters analysis of antenna has been done and optimized. These parameters decide the performance of antenna which we designed. Here the substrate used is Rogers duroid 5880 here the dimensions of X axis and Y axis is given as 8x8cm. And in Z axis it has 0.32cm. Feeding technique used is centre feed. Based on the feeding technique used the optimization is done. At first the design was done separately. Here circularly polarized antenna is taken under consideration. First the circularly polarized antenna is designed and after that the optimization is done with probe fed. The main aim of optimization is to maintain the bandwidth and to increase the return loss value. For good antenna design he return loss should be less than -10db. In this design the return loss value is increased and the frequency range is maintained at 2.25GHz. While doing optimization size of the patch, thickness of the substrate is taken as main parameters. For better results these parameters are consider. By varying these parameters we can yield better results. This antenna is not designed for any application purpose it was just designed to test the optimization results. ANTENNA DESIGN The shape of the antenna used here is circularly polarized. Substrate used here is RT Duroid 5880 and centre fed is used. Figure 1circularly polarized antenna ISSN: 2231-5381 http://www.ijettjournal.org Page 43
This antenna designed at the frequency range of 2.25GHz. The centre patch is cut down to achieve certain frequency range. Radius of the substrate used is 0.32cm. After choosing the substrate sheets are designed i.e.) ground, substrate and patch. Ground plane is set to perfect E port and their dimension is in the range of 9x10cm. And in the wave port the radius is in 0.16cm. also referred to as standing wave ratio. It is the function of reflection coefficient which describes the power reflected from the antenna. RETURN LOSS Return loss is the main factor that we have to take care while designing the antenna. Return loss is nothing but loss of power in the signal returned/reflected by a discontinuity in the transmission line or optical fibre. Discontinuity will happen due to mismatch with the terminating load or with a device inserted in the line. For good antenna the return loss should be less than -10db. Figure 3 VSWR FAR FIELD PATTERN Figure 2 Return loss As said earlier, the return loss should be -10db. In this design the return loss achieved -13.5db. Return loss achieved at the frequency of 2.7GHz. VSWR For a radio to deliver power to an antenna,the impedance of the radio and transmission line must be well matched to the antenna impedance. The VSWR is a measure that numerically describes how well the antenna is impedance matched to the radio or transmission line it is connected to. VSWR stands for Voltage Standing Wave Ratio,and is Figure 4 Far field pattern To find the far field radiation pattern in the project manager dialogue box there is option field overlays after clicking that have to choose port and choose E. after that in the same field overlays there is option called animate when we click that it starts to animate and gives the radiation pattern of the selected field. ISSN: 2231-5381 http://www.ijettjournal.org Page 44
OPTIMIZED ANTENNA DESIGN VSWR Figure 5optimized cp antenna As said while optimizing the antenna should consider the length and width of the patch that taken under consideration. RETURN LOSS Figure 7 VSWR FAR FIELD RAADIATION PATTERN Figure 6 Return loss In this the return loss is achieved less than -16.2db. Hence the optimized antenna is more efficient. Here return loss occurs at the frequency 2.8GHz. ISSN: 2231-5381 http://www.ijettjournal.org Page 45
COMPARISON TABLE FOR CIRCULARLY POLARIZED ANTENNA AND OPTIMIZED CIRCULARLY POLARIZED ANTENNA CIRCULARLY POLARIZED ANTENNA BEFORE OPTIMIZATION AFTER OPTIMIZATION RETURN LOSS FREQUENCY -13.50 2.25GHz -16.29 2.25GHz Table 1 comparison of results In this paper the design was done and optimized using circularly polarized shape. CONCLUSION In this paper the antenna is design to test the antenna parameters using optimization technique. Comparison of outputs was given in the comparison table. In future the frequency range can be increased to specify particular applications. And it can also be optimized for better results. REFERENCES 1. K.S.Tamilselvan, S.Mahendrakumar, Design of Compact Multiband Microstrip Patch Antennas", Journal of Global Research In Computer Science, Vol-3, No.11, Nov-2012. 2. Aidin Mehdi pour, Tayeb A. Denidni, Reconfigurable TX/RX Antenna Systems Loaded by Anisotropic Conductive Carbon- Fibre Composite Material, IEEE Transaction on Antenna and Propagation, Vol.62, No.2, 2014. 3. Ali Ramadan, Mohammed Al- Hussein, A Directional Polarization Reconfigurable Microstrip Antenna, IEEE Transaction Paper-2011. 4. Atser A.Roy, Joseph M, Eta. Enhancing the Bandwidth of a Microstrip Patch Antenna Using Slot Shaped Patch, American Journal of Engineering Research, Vol-02, Issue-09, pp-23-30. 5. Arun Sharma, JagatjitSinghChahal. Design of Compact Microstrip Antenna Using ceramic Substrate, Journal of Engineering Computers and Applied Sciences, Vol-2.No 6, June 2013. 6. Alak Majumder, Rectangular Microstrip patch antenna Using Coaxial Probe feeding Technique to operate in S-Band.International Journal Of Engineering Trends and technology,vol-4,issue 4,April 2013. 7. Boli and Quan Xue. Polarization Reconfigurable Omnidirectional Antenna Combining Dipole and Radiators, IEEE Antenna And Wireless Propagation Letters, Vol-12, 2013. 8. Ghanshyam Singh and Mithilesh Kumar, Design Of Frequency Reconfigurable Microstrip Patch Antenna,2011 6 th International Conference on Industrial and Information System,ICIIS 2011,Aug- 16-19,2011. 9. Huda A.Majid, Mohammad K.A.Rahim, Frequency Reconfigurable Microstrip Patch-Slot Antenna With Directional Radiation Pattern", progress in Electromagnetic Research,Vol.144,319-328,2014. 10. Jeen-sheen Row and Jia-fu Tsai, Frequencyreconfigurable Microstrip Patch Antennas with Circular Polarization, IEEE Transactions and Wireless Propagation Letters, Vol.13, 2014. 11. Lei Ge and Kwai man Luk, Frequency- Reconfigurable low-profile Circular Monopolar Patch Antenna,IEEE Transactions And Propagation,Vol.AA,No.B,2014. 12. M.S.Nishamol,V.P.Sarin eta., An electronically Reconfigurable Microstrip Antenna With Switchable Slot For Polarization Diversity,IEEE Transactions Of Antenna And Propagation,Vol- 59,No-9,Sep-2011. 13. Praveen Kumar,K.Sanjeev Rao eta., The Effect of Dielectric Permittivity on Radiation Characteristics of Co-axially feed Rectangular Patch Antenna,Intenational Journal of Advanced Research in Computer and Communication Engineering,Vol-2,Issue 2,Feb-2013. 14. Rajeshwar Lal Dua,Himanushu Singh,Neha Gambhir, 2.45Ghz Microstrip Patch Antenna with Defected Ground Structure for Bluetooth, International Journal of Soft Computing and Engineering,Vol-1,Issue-6,January-2012. 15. N.Ramli, M.T.Ali, eta. Frequency Reconfigurable Stacked patches Microstrip Antenna with Aperture Coupler Technique, 2012 IEEE Symposium On wireless Technology& Application, Sep 23-26, 2012. 16. E.Ramola, Dr.T.Pearson, Reconfigurable Microstrip Patch Antenna using MEMS:, IOSR ISSN: 2231-5381 http://www.ijettjournal.org Page 46
Journal of Electronics And Communication Engineering,Vol-4,Issue 4(Jan-Feb 2013),PP 44-5. 17. B.Saisandeep, S.Sreenath kashyap, Design and Simulation of Microstrip Patch Array Antenna for Wireless Communications At 2.45Ghz, International Journal of Scientific and Engineering Research, Vol-3, Issue-11, November-2012. 18..B.Sai sandeep, S.Sreenath kashyap, Design and Simulation of Microstrip Patch Array Antenna for Wireless Communications At 2.45Ghz, International Journal of Scientific and Engineering Research, Vol-3, Issue-11, November-2012 19. Dr.Thirmurugan.T,Sundar.k,eta., Circular Polarization wideband E-shaped Patch Antenna for Wireless Applications, International Journal of Engineering and Technical Research,Vol-2,Issue- 3,March-2014. 20. Truong Khang Nguyen and Ikmo park, Effects of Antenna Design Parameter on The Characteristics Of a Terahertz Coplanar Strip line Dipole Antenna, Progress in Electromagnetics and research,vol- 28,129-143,2013. ISSN: 2231-5381 http://www.ijettjournal.org Page 47