Backward wave reduction of a microstrip patch antenna using dual-band isolated soft surface structures

In this paper, dual-band (Bluetooth and Wimax) surface wave suppression structure using novel soft surface structures is presented by a numerical study. The proposed new isolated soft surface structure does not share the ground plane of a patch. It consists of two loops with a corner edged via. By removing the ground plane edges of the patch and forming soft surfaces within the bare substrate, the front-to-back ratio of a patch antenna can be improved. When the 3 different isolated unit cells are used, the front-to-back ratio of a patch antenna is improved to about 7 dB through the use of the proposed new soft surface structure.