Performance Enhancement of a Dual-Band Monopole Antenna by Using a Frequency-Selective Surface-Based Corner Reflector

In this paper, we enhance the performance of a dual-band wire monopole antenna operating at 3 and 5.5 GHz by using a frequency-selective surface (FSS)-based corner reflector. In the proposed design, two reflective FSS screens resonating at 5.5 GHz are placed at an angle of 90° and kept at a specific distance from the antenna. The reflector improves the impedance bandwidth (-10 dB) of the antenna from 20% to 44%, as well as its gain, thereby leading to more directive radiation at 5.5 GHz while maintaining omnidirectional radiation at around 3 GHz. A theoretical study is carried out and presented to estimate the enhancement in the electric field of the composite structure in the desired frequency band compared with the absence of a corner reflector in far field. A significant improvement of 8-10 dBi in antenna gain is achieved over 4.5-6.5 GHz; this is maintained at around 12.5 dBi, with a variation of ±1.5 dBi. Experimental measurements are provided in each case. The proposed design can be used as an omnidirectional radiator at around 3 GHz and as a high-gain directional radiator in the 4.5-6.5-GHz band.