Electronically Switchable Shorted Patch Antenna for Dual-band Operation

The paper describes a shorted patch antenna for dual-band opertaion. A shorted quarter-wavelength patch antenna is used to achieve small dimensions. Two PIN diodes are connected at the non-radiating edges. By reverse and forward biasing the PIN diodes the antenna resonant frequency is switched from 2 GHz to 4 GHz. The antenna prototype is manufactured and the input impedance as well as the E- anf H-plane radiation patterns are measured. The radiation characteristics are good and the radiation pattern shape and cross-polarization levels do not change significantly in a large bandwidth around each of the two resonant frequencies.