Gain enhancement of bow-tie antenna using fractal wideband artificial magnetic conductor ground

Abstract

A novel fractal wideband artificial magnetic conductor (AMC) structure is designed as the ground plane of a printed bow-tie antenna for gain enhancement and low profile. The origin printed bow-tie antenna is operated in the range from 1.67 to 2.06 GHz for a VSWR <2. The AMC structure consists of 6 × 9 first-order fractal unit cells that are made up of four circles and four smaller circles, and the ±90° reflection phase band is 1.1-3.03 GHz. Both the AMC ground plane and bow-tie antenna are fabricated and measured. The distance between the antenna and the AMC is reduced to one-eighth of the wavelength in free space at 1.7 GHz. The experimental results show that the composite antenna has a wide bandwidth from 1.64 to 1.94 GHz, with a relative frequency bandwidth of 16.7%.