Design of an orthogonal feed circularly polarized microstrip array antenna suitable for large scale extensible arrays

摘要

This paper presents a circularly polarized 1×2 array antenna for X-band applications. Both-sided MIC technology is effectively used to design this array antenna as the array antenna consists of both microstrip lines and slot lines to realize the feed network. Patch elements and microstrip lines are placed on the top surface of the substrate and slot lines on the reverse surface (ground plan) of the substrate. Each of the patches is excited by two orthogonal feed lines. One of the feed lines is ahead by an odd multiple of quarter wavelength than the other feed line. This strategy makes the each patch circularly polarized. The impedance bandwidth is about 630 MHz and the 3-dB axial ratio bandwidth is more than 1%. This array antenna is very suitable to make large scale extensible array antennas by using it as a unit array.