Effects of load impedance on the dimensions and beamwidth of a dual feed nearly square patch antenna for circular polarisations

The authors present a model for the dual-feed nearly square patch antenna which accounts for the loading effects of the output port upon the antenna. Theory indicates that the required antenna dimensions depend on the load impedance seen by the antenna. It is also seen that the axial ratio bandwidth of the antenna can be varied by correct choice of load impedance. Typical results of antennas designed to operate at 2.450 GHz indicate a broadening of the 3 dB axial ratio bandwidth from approximately 19 MHz with a load impedance of R/sub L/=1.0 M Omega to a value in excess of 130 MHz for R/sub L/=50 Omega .< >