Design of Frequency Reconfigurable Hexagonal Antennas for WLAN Applications

In this paper, design methodology of a frequency reconfigurable probe-fed hexagonal patch antenna with a hexagonal annular ring has been discussed using a varactor diode as the tuning element. The proposed technique is applied to two separate antennas; first antenna is capable to switch between different frequency modes covering the WLAN channels (5.2 GHz - 5.825 GHz) while second frequency-reconfigurable antenna covers Wi-Fi channels (2.4 GHz - 2.5 GHz) by means of varying the reverse bias capacitance of the diode via changing the bias voltage. Based on CST MWS simulation results, both the antennas are found to be radiating at their fundamental mode in all the switching bands with same and matched impedance. A gain of around 1.9 dB is observed during simulation in both antenna designs. The structure of both antennas is easy and economical to implement as only one varactor diode is required to achieve reconfigurability. The antennas find their usefulness dynamic frequency selection (DFS) within WLAN 5 GHz band and 2.4 GHz Wi-Fi channel selections.