Reconfigurable Patch Antennas with Four- Polarization States Agility Using Dual Feed Ports

Polarization reconfigurable patch antennas which can switch polarization states among vertical and horizontal linear polarization (LP), leftand right-hand circular polarization (CP) is demonstrated in this paper. The original orthogonal linear polarized antenna is a square patch fed by two ports at the adjacent edges. CP operations can be activated by introducing perturbations at the opposite corners of the patch. If a diode is loaded on every perturbed corner, the antenna polarization states can be alternated by controlling the bias voltage of two PIN diodes. Perturbation elements can be cut on the patch or on the ground. Two antenna prototypes are suggested, simulated, and verified by experiments. These polarization reconfigurable antennas have good antenna performances of low reflection coefficient, axial ratio, and cross-polarization (X-pol), and high isolation between two LP operations. They have concise structure with only two PIN diodes being required. The two reconfigurable antennas are low cost and can be integrated easily in wireless communication systems.