Short backfire antenna with microstrip Clavin feed

A single short backfire antenna has an enclosed structure with no sharp projections and approximately 15 dBi gain, making it attractive for handheld radio monitoring and other man-portable applications. However, a microstrip patch fed short backfire antenna had a broad E-plane radiation pattern main lobe, leading to a loss of gain and low aperture efficiency. The antenna was studied using a commercially available Method of Moments software. Adding eight parasitic wires inside the cavity of a short backfire was found to narrow the E-plane radiation pattern main lobe, making it more like the H-plane radiation pattern and increasing the peak gain by 1.5 dB. A single proof of concept antenna was built at 1.49 GHz, which had a bandwidth of 2.3%, aperture efficiency of 78% and was shown to have equalised principal plane main lobes.