A Planar Polarization-Reconfigurable Antenna

This paper reports a planar polarization-reconfigurable antenna with a simple switching topology. A dual-mode substrate integrated waveguide (SIW) cavity is adopted for the element antenna having two input ports. Four radiation slots are etched on the top surface of the SIW cavity for generating the circularly polarized radiation, whose radiation phases can be adjusted by switching the input port. The left-hand circular polarization, right-hand circular polarization, and linear polarization can be realized by properly choosing the state of the excitation. A $2 \times 2$ array antenna is designed for the demonstration of the array application, and experiments are carried out to validate the design. Good agreement among the simulated and measured results is obtained. Different to the reported antenna architectures in the studies, which usually require complicated switching networks and more switching elements when designing an array for obtaining a high radiation gain, the proposed array antenna does not need additional switching elements for the large array applications. It has a low cost and a simple structure, and can be used for the polarization diverse applications of the wireless system.