A frequency-reconfigurable slot loop antenna using ferroelectric MIM capacitors

Abstract

A frequency-reconfigurable antenna based on periodically loading ferroelectric MIM capacitors along a slot loop is designed, fabricated, and measured. The antenna is fabricated on a 430-µm-thick sapphire substrate with a total area of 1×1cm². The size of the slot loop is 2.5×2.5mm². By changing the bias voltage of the ferroelectric varactors from 0V to 7V, the resonant frequency of the varactor-loaded antenna can be tuned from 5.57GHz to 7.33GHz, corresponding to a tuning range of 27.3%, while keeping the return loss greater than 10dB. At 5.57GHz, the size of the slot loop is 0.046×0.046λ₀². When biased at 7V, the antenna gain is −10.8 dBi at 7.35GHz. Under 0-V bias, the P_in,1dB of the tunable antenna is 18.8dBm at 5.6GHz.