Frequency Agile Slot Antenna Using Contactless Capacitive Loading

In this paper, a reconfigurable slot antenna capable of tuning a full octave in frequency from 2 GHz to 4 GHz is presented. The design is based on changing the capacitive loading of a slot antenna by physically displacing a metal plate connected to a piezoelectric linear actuator that changes the apparent electrical length of the antenna. The antenna was simulated, fabricated, and measured to tune across the 2-4 GHz frequency range while maintaining a maximum return loss of greater than 9.0 dB. Simulations also show a 65.74% to 95.75% radiation efficiency across S-band. A broadside realized gain of greater than 1.73 dB was measured over the entire tuning range. Moreover, the tuning mechanism was proven robust above other methods by withstanding up to 100 W of power incident on the feed at 3 GHz.