I. Introduction
In the recent years, the low cross-polarization microstrip patch antennas for phased arrays have been gotten strong attention, mostly are applied in target-tracking radars and weather radars [1]. Feeding methods play vital role in decreasing cross-polarization levels, conventional feed technique, such as, microstrip feedline, coaxial probe [2], while both of them can’t realize decent low cross-polarization at the same time keep wide impendance bandwidth [3][4]. Aperture coupled feed, as non-contanct feeding structure, can easily achieve the combination of low cross-polarization and large bandwidth [5].