INVESTIGATIONS ON A CIRCULARLY POLARIZED SQUARE PATCH ANTENNA

Abstract

Thare are various type of single fed and dual fed Circular Polarized (CP) patch antennas which have wide area of applications such as automobile and mobile satellite communication. This dissertation presents a study of the T-junction power splitter fed circularly polarized square patch antenna. A theoretical formulation has been carried out for the case of a microstripline fed patch antenna, which can be extended to analyse a microstrip antenna with dual feed. For the analysis of microstripline fed patch antenna, the moment matrix formation and various matrix element expressions have been presented here. The currents on the feed line are expanded in terms of subsectional piecewise sinusoidal modes (PWS) near the discontinuity with entire domain travelling-wave modes used to represent incident and reflected wave from discontinuity. The current on the patch is expanded in terms of entire domain modes. Various experimental results have been presented here on axial ratio, Gain and Radiation patterns of the antenna. The boersight axial ratio comes out to be nearly 2db at the resonant frequency. A computer program in MATLAB has been written here to implement the analytical procedure. The proposed antenna is fabricated on a RT-5880 Duroid substrate for operation in the S-band.