A Low-Profile Dual-Band Full-Space Antenna Combining an FTA and a Multipolarized FPCA

Previously reported bidirectional radiating hybrid Fabry–Pérot cavity antennas and folded transmitarray antennas employing polarization multiplexing can generate only a single-polarization beam in each spatial direction, and often suffer from limited bandwidth and efficiency. To address these limitations, a novel frequency-multiplexed bidirectional radiating hybrid antenna is proposed. The antenna consists of a lower multifunctional metasurface, an upper multifunctional metasurface, a low-band patch antenna, and a high-band waveguide feed. A prototype was designed, fabricated, and experimentally verified, showing good agreement with simulations. At Ka-band, the antenna achieves <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</i>-polarized radiation with a 3-dB gain bandwidth of 28.4% and a peak aperture efficiency of 37.5% in the upper hemisphere. At X-band, it provides 3-dB gain bandwidths of 10.8% and 8.9%, with corresponding aperture efficiencies of 31.6% and 32.6% for the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</i>- and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">y</i>-polarizations in the lower hemisphere, respectively. Furthermore, a quadrature phase shift keying wireless link was established to demonstrate the system-level performance of the multipolarized capability at X-band.