Design of Truncated Corner Circularly Polarized Rectangular Microstrip Antenna

Abstract

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.