Development of capacitor-based tunable frequency selective surface for wireless communication

This paper deal with the development of frequency selective surfaces (FSS) structure with tunable bandpass characteristic. The primary resonant frequency of FSS is 2.4GHz which is suitable for wireless communication system. Basic principle of tunable FSS is the ability to tune the resonant frequency by varying the reactance value of the unit cell circuit. It can be accomplished by using solid-states diodes like varactor, PIN diode and Schottky diode. By varying the DC voltage across the varactor, varactor will give varied capacitance values. In this work, capacitors with several values, namely 1pF, 2.2pF, 3pF, 3.9pF, 4.7pF, 5.6pF and 6.8pF will be used as the representation of capacitance values of varactor. The simulation results show that for the variation of capacitance value between 1pF and 6.8pF, the resonant frequency shifts from 2.6GHz to 2.36GHz. The bandwidth also changes from 130MHz to 260MHz. The measurement results also show that the resonant frequency shifts as the capacitance value changes.