Aperture-Coupled Low-Profile Wideband Patch Antennas for CubeSat

This communication presents the design and measurement results of aperture-coupled stripline-fed wideband patch antennas for nanosatellite applications. The low-profile requirements lead to a strong back radiation from the coupling aperture. Instead of suppressing the resulting electric field in the feeding stripline, an advantageous field distribution is used to boost the electromagnetic coupling to the radiating element. This effect is achieved by enclosing the stripline feeding structure with vertical conductive walls, effectively creating a cavity. The obtained antenna has a low profile of 0.08 λ0 at 2 GHz and exhibits 3 dB gain and axial ratio bandwidths of 27% and 32%, respectively. The effect of cavity resonances is analyzed in detail and we show how it is used to reduce the interference in adjacent frequency bands. This communication also proposes an elegant method of integrating this type of antennas into the satellite chassis, which reduces the antenna extrusion on the satellite surface. The two proposed methods are demonstrated through another antenna prototype mounted on a low-cost CubeSat mock-up.