Resonant Frequency Analysis using Perturbation and Resonant Cavity Method in Printed Dual Band Antenna for WiMAX Application

A printed dual-band antenna is designed to resonate at 3.5 GHz with the measured gain of 6.38 dBi and at 5.5 GHz with that of 5.84 dBi for the WiMAX application. The bandwidth of this antenna at 3.5 GHz and 5.5 GHz is 8% and 5%, respectively. The radiation efficiency of 91.45% is obtained at 3.5 GHz and that of 89.56% at 5.5 GHz. A novel approach based on the perturbation technique is used to relate the resonant frequency to the electromagnetic energy stored and the volume of the proposed antenna’s structure. The dual resonant length of this antenna is determined by a parameter named as the length reduction factor, which is computed by the curve fitting method. A polynomial equation connects the length reduction factor and resonance frequency. The resonant cavity model has been used to derive the resonant frequency equations for dual bands. The simulation and measured results are used to validate the analytically predicted resonant frequency caused by the structure perturbation and cavity technique and show good agreement. This antenna is fed by a balanced parallel plane, which conveniently facilitates the PCB’s integration.