A Metasurface-Loaded Wideband High-Gain Filtering Antenna Array for CubeSat Application

Abstract

This letter presents a Ka-band high-gain antenna array loaded with a three-layer metasurface (MS) superstrate filter for radiation-domain filtering and in-band gain enhancement. The reference radiator source is a single-port 8 × 8 patch array designed at the 29.2 GHz center frequency. A new shape three-layer bandpass MS filter with a good roll-off factor is positioned above the array with an optimized air gap. Unlike conventional filtering antennas that mainly exhibit selectivity in the input reflection coefficient, the proposed structure shows its dominant filtering effect in the realized-gain and efficiency responses, while maintaining acceptable impedance matching. The operating mechanism uses the MS’s bandpass transmission response and the induced E-field on the MS superstrate by the incident wave of the reference array. This configuration simultaneously enhances in-band realized gain through constructive interference, while suppressing out-of-band radiation via the MS’s frequency-selective rejection. Simulated and measured results confirm that the proposed MS-loaded filtering array preserves good in-band matching from 27.5 GHz to 31 GHz, covering the Ka-band uplink, and improves the boresight gain by approximately 3.1 dBic at 29.2 GHz, while attenuating the undesired lower band gain by 21.1 dBic and the upper band by 20.4 dBic. These metrics make it suitable for Ka-band CubeSat communication systems.