A reconfigurable patch antenna with quadri-polarization states using dual feed ports

A novel reconfigurable microstrip antenna that can switch operating polarization states among vertical and horizontal linear polarization, left- and right-hand circular polarization is proposed in this paper. The original square patch is fed by two orthogonal ports, which excite horizontal and vertical linear polarizations. Two opposite corners are slotted on the patch with a diode being loaded on every slot. By controlling PIN diodes and using different feed ports, the polarization sense alternates among four states. The antenna´s performances of the four polarization states are simulated and measured. This polarization agile antenna has good radiation characteristics, concise structure and low cost.