Analysis and Design of a Reconfigurable Antenna Based on Half-Mode Substrate-Integrated Cavity

The detailed analysis, design, and optimization of a reconfigurable antenna based on a periodically stub-loaded half-mode substrate-integrated waveguide (HMSIW) cavity is presented in this paper. The analysis demonstrates an excellent prediction of the resonance frequency for the cavity with an error of less than 2% compared to numerical simulations performed over a wide range of parameters. The fast computation of the resonance frequency based on the analytical model gives deep insight into the antenna operation and allows an efficient optimization process. The reconfigurable antenna has been designed and optimized to cover the whole S-band (WR-284 waveguide band), i.e., 2.60-3.95 GHz, using three varactors with measured capacitance varying from 0.149 to 1.304 pF. Experimental results validate the concept across the whole tuning range, with a return loss and antenna gain greater than 15 and 2.1 dB, respectively at resonance.