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Wideband Circularly Polarized Fabry–Perot Resonator Antenna in Ku-Band

A gain enhancement method is proposed for the circularly polarized (CP) magneto-electric dipole antenna (MEDA) over the whole Ku-band in this letter. Together with the CP MEDA as a feeding antenna, a single-layer partially reflecting surface made by a substrate with arrays of metal patches printed on both the top and bottom forms a Fabry–Perot resonator antenna. Five types of symmetrical patch, i.e., double printed circular, square, circular-ring, square-ring patches, and single printed circular patch, are compared and optimized for a better reflective phase property. Finally, the circular patch type is chosen because of its gentler reflective phase gradient, and hence the gain value of the CP MEDA is much enhanced over the whole operating band. A prototype is optimized and fabricated to verify the analysis. Measured results show that the 10 dB return-loss bandwidth is about 54% (11.7–19.8 GHz), the 3 dB gain bandwidth is 42.3% (11.7–17.2 GHz), and the 3 dB axial-ratio bandwidth is about 29.3% (12.4–16.8 GHz). The overlapped bandwidth of the three is 29.3%, and the maximum CP gain is 11.45 dBic at 14 GHz. A gain enhancement of about 2.1–5.2 dB is achieved as compared with the unloaded type. This method is a good option to design antennas in satellite communication with the merits of wide CP bandwidth.