Frequency Agile Triple Band Microstrip Antenna for WLAN / WiMAX Application

A frequency agile triple band microstrip antenna using defected ground structure for WLAN/WiMAX application is presented, in which frequency agility is electronically achieved by changing the bias voltage of varactor diode. A defected ground structure rectangular patch with dual inverted L-shaped fed with a cross shaped strip line is used to achieve multiple bands. Simulated results are validated by the experimental results and show a good agreement between simulated and experimental results. The proposed antenna has small size and operates 2-2.15 GHz, 2.75-3.5204 and 5.4-5.9 GHz. The lower and upper band remains almost constant while resonance frequency of the middle band is changing with the bias voltage of varactor diode and frequency agility of 768.4 MHz is achieved. Thus the proposed antenna is suitable to be used for WLAN and WiMAX applications.