Beam-Switching Digital Metasurface Reflectarray Antenna With Extreme Offset Illumination for Satellite Communications

This article introduces a compact wideband beam-switching digital metasurface reflector (MSR) array antenna featuring extreme offset illumination for satellite communications in the Ka band. The MSR comprises phase-modulating subwave length unit cell elements. The unit cell consists of a cross dipole loaded with curved stubs. The arrangement of the stubs across the dipole modulates the phase characteristics of the incident electric field. An MSR composed of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$15\times 15$ </tex-math></inline-formula> metabits is designed, fabricated, and validated. The metasurface reflectarray is excited by three antipodal Vivaldi antennas with an extreme offset configuration, which effectively mitigates the blockage due to the feeding source. The measured results show highly directive, stable beam-switching characteristics over a broad spectrum ranging from 26 to 32 GHz. A beam steering range of −35° to +35° is obtained along the azimuthal plane, with a maximum measured peak gain of 19.1 dBi at 28.5 GHz and maximum beam-switching loss of 1.5 dBi. A maximum measured aperture efficiency of 35% is obtained, and a 3-dB gain bandwidth of 20.7%.