Liquid-Dielectric-Based Patch Antenna with Polarization and Frequency Reconfiguration

In this work, a novel tuning concept is proposed for patch antennas with reconfigurable polarization and center frequency tunability. The proposed tuning concept is based on a cavity-based dielectric substrate whose dielectric properties are tuned by altering the height of a liquid dielectric (LD) within four air-filled cavities. Specifically, when two diagonal cavities are filled with LD, right-hand circular polarization (RHCP) or left-hand circular polarization (LHCP) can be obtained with wide impedance matching. Furthermore, by filling with LD two adjacent cavities, linear polarization (LP) can be realized. It is shown that by tuning the height of the LD in the LP mode of operation continuous center frequency tuning between 3.3 to 4.0 GHz can be achieved while obtaining good radiation pattern characteristics. The cross-polarization of the antenna in the LP state is lower than -25 dB for all tuning states, and the gain loss is less than 0.15 dB when compared with a static patch antenna built on the same substrate.