Low-profile metamaterial antenna with near-arbitrary tunable polarization

Antennas operating in the low UHF band have conventionally required thicknesses in the tens of centimeters. Artificial magnetic conducting (AMC) substrates have been shown to reduce the profile (height) of these antennas, but at the expense of operating bandwidth. Adding tunability has restored the flexibility of dynamically adjusting the communication channel over a wide range. Here we introduce a low-profile antenna system with additional tunability that produces a reconfigurable polarization for a 1-2% operating channel adjustable across a wide overall bandwidth, all from a single feed without phase shifters. The polarization is controlled by adjusting the input admittances of crossed end-loaded dipoles; a 90° difference in the phase of the input admittances leads to circularly polarized radiation. Varying the tuning parameters can also lead to either right-handed or left-handed circular or elliptical polarizations, as well as linear polarizations with various orientations.