Wideband Fabry–Perot Resonator Antenna Employing Multilayer Partially Reflective Surface

A method for designing wideband Fabry-Perot resonator antennas (FPRAs) using multilayer partially reflective surface (PRS) is presented. The proposed partially reflecting structure employs a pair of closely spaced PRSs to obtain a positive reflection phase gradient over a wide range of frequencies. Each PRS layer is composed of complementary square apertures and patches printed on either side of a thin dielectric sheet. The distance between the two PRS layers is only λ
_o
/12 ( λ
_o
being wavelength at the center frequency of 13 GHz). Due to the presence of strong couplings between the two PRS layers, the designed PRS unit cell gives a positive reflection phase gradient from 11 to 15 GHz, thereby forming the basis of a wideband FPRA. Based on the proposed PRS, a compact FPRA with overall dimensions of 2.4λ
_o
×2.4λ
_o
×0.66λ
_o
is designed and experimentally validated, which gives a 3 dB gain bandwidth and a maximum realized gain of 32.3% and 14 dBi, respectively.