Compact circularly-polarized microstrip array antenna

Abstract

This paper presents a compact circularly-polarized microstrip array antenna with four square patches fed in phase quadrature such that a phase shift of 90° between each neighbouring patches, thus providing circularly polarized pattern. The feeding network is placed on the opposite side of the patches' ground plane and is designed using three Wilkinson power dividers having different output lengths that achieve the required phase shift between patches.