A quadrature-hybrid-integrated reconfigurable feeding network for wideband quad-polarization-agile antenna design

In this article, a reconfigurable antenna with quad-polarization radiations is proposed based on a switchable feeding network. A wideband quad-mode feeding network is first designed by integrating a simple impedance converter with a modified hybrid coupler. By switching the p-i-n diodes, four-transmission status with specific amplitudes and phase differences at feeding output ports can be obtained over a wide frequency range, hence enhancing the radiating bandwidth of two linear and two circular polarizations. Finally, a prototype of the proposed quad-polarization-agile reconfigurable antenna is designed and fabricated. The measured results show a wide overlapped bandwidth of 782 to 1010 MHz (25.4%) for all four polarizations with a competitive size and gain performance.