Analysis of Circular Microstrip Antenna with Single Shorting Post for 50 Ω Microstrip-Line Feed

In this paper, a technique using a single shorting post has been used to match the peripheral impedance of the circular microstrip antenna (CMSA) with that of the 50 Ω-microstrip (MS)-line feed. The shorting posts perturb the current distribution on the patch, altering the input impedance at the periphery. Thus, by selecting shorting post positions, a wide range of impedance has been adjusted without changing the patch geometry. A systematic analysis of the performance of the CMSA at a lower order mode and fundamental mode frequencies with a loading of a single shorting post has been presented. Simulated results of the directly 50 Ω-MS-line-fed CMSA are experimentally validated with good agreement.