Microstrip Antennas Gain Improvement Using Frequency Selective Surfaces

In this paper, the gain of an Ultra-Wide Band (UWB) micro-strip antenna is improved using a rejected band Frequency Selective Surfaces (FSS) structures. The FSS is inserted below the planar antenna to reflect the electromagnetic energy radiated by the antenna, which leads to the improvement of the planar antenna’s gain. Two structures can be inserted below the antenna to improve its gain, the first structure is a metallic plan, the second one is an UWB FSS, which its unit cell comprises three U-shaped patterns. To find the optimal distance between the antenna and the inserted structures an optimization is applied. In addition, an optimization to find the number of FSS unit cells is affected. The use of the FSS structure to increase the gain of this antenna can be envisaged for the frequency from 2 to 7.5 GHz. Simulated results obtained by the HFSS software.