Polarization Reconfigurable High-Gain Fabry–Perot Cavity Antenna

We propose an innovative polarization reconfigurable high-gain Fabry–Perot cavity (FPC) antenna. The antenna can electrically select its polarization among three linear polarization (LP) modes of
$x$
-,
$y$
-, and 45°-direction with stable high gain. To achieve these properties, we devise a novel polarization conversion partially reflective surface (PCPRS) as a superstrate. The PCPRS plays two crucial roles simultaneously; it reconfigures antenna polarization and maintains high gain using an FP resonance between the PCPRS and a ground plane. The FP resonance, which is the key point in our antenna design, is essential to maximize both antenna gain and polarization reconfigurability. Therefore, in order to stably achieve the FP resonance for all three polarization modes, we have designed the PCPRS to keep its reflection behavior as constant as possible for all LP modes. To the best of our knowledge, this is the first FPC antenna introducing a partially reflective surface (PRS) which also functions as an active polarizer. Consequently, the proposed antenna attains remarkable polarization conversion performance with higher than 20 dB cross-polarization suppression level for all polarization modes. Moreover, in all modes, our antenna well maintains reasonably high gain of about 15 dBi with good impedance matching properties. Good agreement between measurements and simulations proves the validity of our design approach.