A broadband rectangular-cavity-backed meandering slot antenna

Flush-mount slot antennas are used in high speed moving vehicles, such as rockets, airplanes and trains, in order to get low wind resistance. A cavity-backed slot antenna has some advantages over a microstrip antenna as regards higher power handling capability and higher efficiency. It usually shows narrowband impedance characteristics due to the resonance of the cavity, but it is reported that an S-type slot antenna with a rectangular cavity shows a VSWR bandwidth (<2) of 23% (Kotani, T. and Hirasawa, K., IEEE Antennas and Propag. Soc. Int. Symp., 2003.). Thus an increased bandwidth can be obtained by changing the shape of the slot. The paper introduces a meandering slot antenna to obtain a broader impedance bandwidth. The meandering slot shape is based on the series connection of the S-type slot antenna. The antenna over an infinite ground plane is backed by a rectangular cavity to get radiation into one side only. The characteristics are investigated numerically and experimentally. VSWR bandwidth (< 2) of 26% is obtained. The radiation patterns are not changed much in the band for VSWR < 2.