Analysis of a ridged circular disc microstrip antenna element using the cavity model

A theoretical analysis of a ridged circular patch microstrip antenna element is presented by modelling it as a cylindrical cavity with a magnetic wall along its edge. The approach is based on conserving the reaction at the ridged position. This antenna, excited in the dominant mode, resonates at higher frequencies and has a wider bandwidth than a simple conventional circular patch antenna with the same size. Design graphs show the variation of the resonant frequency, quality factor, radiation efficiency, feeding position at resonance and bandwidth (VSWR ⩽2), for the dominant mode as a function of the ratio of inner to outer-disc radius for different ridge thicknesses