New microstrip radiator feeding by electromagnetic coupling for circular polarization

We present a novel feeding system for microstrip radiators which is based on electromagnetic coupling. The effects of the antenna's key design parameters have been studied and discussed. This new feeding system was found to be very simple and useful in the design of flat arrays and reflectarrays using microstrip patches. A novel circularly polarized patch radiator fed from only one input line and based on the proposed feeding system is also presented in this paper. The result of the developed prototype in axial ratio bandwidth is double that obtained with a typical microstrip patch fed from two inputs.