Effect of reduced ground plane in a vertex-fed hexagonal C-band antenna

Vertex-fed hexagonal planar antennas excite higher order modes. Monopole like radiation characteristics may be achieved through ground plane reduction. The paper presents the effect of reduced ground plane (RGP) which may be used as a technique to excite a higher-order mode and suppress spurious frequency radiation, if any, due to probe feeding. The designed antenna structure has a hexagonal slot at the centre of a hexagonal patch fed through a probe at a vertex of the hexagon. To understand the effect of RGP on antenna performance, an equivalent circuit model is analyzed and discussed. A study on surface current distribution over patch surface confirms radiation of TM
₁₂
mode. The proposed C-band antenna exhibits a gain of 3.84 dB at 5 GHz and a bandwidth of around 600 MHz that makes it suitable for indoor WLAN applications.