Axial ratio analysis of a multiple-feed microstrip antenna

This paper focuses on the axial ratio bandwidth, and gives out the theoretical computation of the axial ratio bandwidth of a multiple-feed microstrip antenna. The more feeds, the better the axial ratio is. When using multiple-feed for one patch, sequential rotation technology can be adopted. Starting from the mechanism of circular polarization obtaining from multiple-feed method, the detail analysis of axial ratio including when the amplitudes have some difference and the phase excitation of the feed point has an offset according to the designed central frequency are described.