A Review on Adaptive Frequency Selective Surfaces (AFSS) based Patch Antennas

This paper presents a survey on recent developments in the area of Adaptive Frequency Selective Surfaces (AFSS) integrated patch antennas. The study reveals that the limitations of the FSS based microstrip antennas mainly; narrow impedance and gain bandwidth can be overcome by using adaptive FSS (AFSS). It is shown that the integration of the lumped-element devices on the FSS has several advantages like radiation bandwidth enlargement, controlling the resonance frequency, high directivity etc. Hence the various FSS structures loaded with different electronic components/devices such as capacitors, inductors, varactors as well as PIN diodes have been considered. The simulation results of these structures reveal the effect of these devices on the transmission and reflection characteristics as well as overall performances of the antennas. The frequency tuning over 500-700 MHz around 2.5 GHz has been reported along with considerable reduction (approximate to 55%) in the total area of the patch antenna. In addition, it has also been found that the variation of adaptive FSS superstrate height, changes the operating frequency. The range of variation is approximately 100 MHz.