Tunable patch antenna using a liquid crystal substrate

Patch antennas are attractive in many mobile communication applications since they are light-weight and simple to manufacture. However, the traditional patch antenna suffers from narrow frequency bandwidth. In this paper, we propose the use of a liquid crystal substrate for a patch antenna whose frequency can be tuned by changing the biasing voltage across the substrate. It has been found by simulations that by varying the biasing voltage from 0 V through 11 V, the operating frequency of the circular patch antenna can be varied from 1.08 GHz through 2.35 GHz. We have also proposed two novel applications for such tunable antennas: (i) antenna based modulation (ABM) and (ii) antenna based frequency diversity (ABFD).