Application of sequential feeding to wide bandwidth, circularly polarised microstrip patch arrays

Abstract

Sequentially rotated feeding of circularly polarised microstrip arrays gives substantial improvements in performance and is an important new technique finding application in several current systems. Here, the application to microstrip arrays is examined. A detailed analysis of patch arrays with corporate feed networks incorporating non isolating splitters is described. Computed results for input VSWR and axial ratio for various array configurations show that, for best performance, the isolated patch VSWR and ellipticity on resonance should be optimised and that maximum bandwidth is obtained for clusters of three circularly polarised patches. Gain loss is found to be a significant bandwidth constraint resulting in an overall bandwidth not substantially wider than that of linearly polarised patches. It is concluded, however, that sequential rotation will allow use of lower Q patches leading to good array ellipticity and match over wider bandwidths than currently possible.