Formulations and design procedure for three layer suspended and non-suspended configurations of rectangular slot cut rectangular microstrip antenna have already been reported. In this paper, atruncated cornerrectangular microstrip antenna to realize circular polarization on thinner substrate is proposed. The truncated cornersdegenerates' fundamental TM10 mode into two orthogonal modes, to yield circular polarization. To improve upon the gain, three layer suspended configuration is proposed which yields VSWR and axial ratio BW of 49 and 9. 5 MHz, respectively. The antenna yields gain of more than 6dBi over the axial ratio bandwidth. Further the formulation in resonant length at two orthogonal modes for truncated corner patch on non-suspended and suspended configurations is proposed. The frequencies calculated using them closely agrees with the simulated results. Using proposed formulations, the design procedure for truncated corner circularly polarized rectangular microstrip antenna in 1000 to 4000 MHz frequency band, is presented. It gives circularly polarized response with formation of small loop (kink) inside VSWR = 2 circle in the smith chart. Thus the proposed formulation can be used to design circular polarized antenna at any given frequency.

1. G. Kumar and K. P. Ray, "Broadband Microstrip Antennas," Artech House, USA, 2003
2. K. L. Wong , "A Compact and Broadband Microstrip Antennas," John Wiley & Sons, Inc. , New York,2002.
3. R. Garg, P. Bhartia, I. bahl, A. Ittipiboon , Micristrip Antenna Design Handbook", Artech house Inc. , 2001.
4. P. C. Sharma and C. K. Gupta,"Analysis and Optimized Design of Single Feed Circularly Polarized Microstrip Antennas," IEEE Transactions on Antennas and Propagation, vol. AP-31, NO. 6, Nov 1983.
5. W. S. Chen, "Small Circularly Polarized Microstrip Antennas," IEEE Antennas and Propagation Society International Symposium, 1999.
6. K. L. Wong and T. W. Chiou, "Single-Patch Broadband Circularly Polarized Microstrip Antennas," IEEE Antennas and propagation society international symposium, 2000.
7. K. Y. Lam, K. M. Luk, K. F. Lee, H. Wong, and K Bong, "Small Circularly Polarized U-Slot Wideband Patch Antenna," IEEE Antennas and Wireless Propagation Letters, Vol. 10, 2011.
8. A. Khidre, K. F. Lee, F. Yang, and A. Eisherbeni, "Wideband Circularly Polarized E-Shaped Patch Antenna for Wireless Applications," IEEE Antennas and Propagation Magazine, Vol. 52, No. 5, October 2010
9. K. F. Tong and T. P. Wong,"Circularly Polarized U-Slot Antenna," IEEE Transactions on Antennas and Propagation, Vol. 55, NO. 8, AUGUST 2007
10. A. Deshmukh, et al. "Design of Slot Cut Circularly Polarized Rectangular Microstrip Antenna", Proceedings of International Conference on Communication Technology September 2015.
11. IE3D 12. 1, Zeland Software, Fremont, USA, 2004.

Rectangular microstrip antenna Circular Polarization truncated corner suspended microstrip antenna