Circularly Polarized Polarization Conversion Metasurface-Inspired Antenna Array With Low RCS Over a Wide Band

A circularly polarized (CP) metasurface-inspired antenna array with a low radar cross Section (RCS) over a wideband based on polarization conversion metasurface (PCM) is proposed. Without increasing the structural complexity, the PCM units serve directly as antenna radiators, which not only maintains good radiation characteristics but also reduces both the in-band and out-of-band RCS of the antenna. Simulations show that the proposed PCM-inspired antenna array has an impedance bandwidth of 37.6% (8.2–12 GHz), a 3 dB axial ratio (AR) bandwidth of 32.5% (8.5–11.8 GHz), and a 3 dB gain bandwidth of 23.3% (9.5–12 GHz). The RCS of the proposed antenna array is greatly reduced for both polarizations in the frequency range of 7.6–16.2 GHz (72.3%) compared to the conventional microstrip patch antenna array, with a maximum reduction of 20.6 dB. Moreover, the proposed PCM-inspired antenna array has a smaller element size compared to conventional low-RCS metasurface antennas, making it more conducive to the composition of a phased array. Finally, the proposed array is fabricated and measured, and the results confirm the simulations.