Increasing the gain of a semicircular slot UWB antenna using an FSS reflector

Abstract

In this paper we demonstrate the gain enhancement of a semicircular slot antenna using a multilayer frequency-selective surface (FSS). A theoretical analysis of the FSS with a UWB semicircular slot antenna is presented. The multilayer FSS provides an appropriate reflection phase to act as a reflector and is able to enhance the gain of the slot antenna. Simulations show a linear phase response from 3.5 GHz to 12 GHz that is sufficient for ultra wideband operation. A significant improvement of 3 to 4 dB gain over the whole frequency range is demonstrated. The composite antenna has a theoretical gain of 8 dBi and a very small maximum gain variation of ±1.5 dB over the 3.5 to 10 GHz frequency range. Its compact configuration provides flexibility for mounting the reflector close to the slot antenna and makes it more suitable for modern UWB devices.