Study on the elimination of surface wave by metal fences

The microstrip antenna is a low-profile planar structure and is inexpensive compared with other types of antennas due to the ease of manufacture. However, patch-antenna designs have some limitations such as restricted bandwidth, low gain, and a decrease in radiation efficiency due to surface wave modes. Surface wave modes in microstrip substrates may cause the undesired energy losses and the reduction of the radiation efficiency of the patch antenna. A scheme to eliminate such modes by using metal fences is proposed. This structure can be easily realized by a metalated hole in manufacturing. It is observed that the patch antenna with this structure shows reduced levels of surface wave modes, thus improving the gain and the radiation pattern.