The Impedance Variation with Feed Position of a Microstrip Line-Fed Patch Antenna

Abstract

This paper presents a very precise analysis of the impedance variation with feed position of a microstrip line-fed patch antenna. The influence of the inset length and width has been investigated, taking into account finite size of the substrate, various lengths of the feeding microstrip line, losses and finite thickness of metallization. The obtained numerical results are compared with the previously published ones, showing very good agreement. However, the results of the additional analysis confirmed that the mathematical functions proposed in previously published papers (the cosine-squared function and the cosine to the fourth power function) are not really good approximations of the input impedance behavior for this type of the microstrip patch antenna.