Design and development of a novel compact soft-surface structure for the front-to-back ratio improvement and size reduction of microstrip Yagi antenna arrays

A new soft surface (SS) configuration is proposed that can improve the front-to-back (F/B) ratio significantly while maintaining a high gain for any planar antenna array. In addition, the size of this array -including the finite substrate dimensions - has been reduced in comparison to the non-SS design's size. As a benchmark, the proposed SS structure is implemented to the printed microstrip Yagi array design proposed in [1] to achieve a new design with a higher gain and a compact size, that was analyzed for different ground sizes around 5.8 GHz. It is observed that an improvement of at least 3 dB in the F/B ratio and of at least 1 dBi in gain are obtained. Experimental results verify the claims presented in this paper.