Planar Surface-Wave Antenna for CubeSats with Directive Radiation Exactly at Endfire

A two-layer planar surface-wave antenna (SWA) with directive gain exactly at endfire is proposed for applications including integration with solar panels, CubeSats, and other small satellites. Moreover, by co-design and including air vias (AVs) for the surface-wave aperture, the structure becomes semi-transparent and can be positioned on top of solar panels, and this can improve solar power harvesting capabilities. Structure excitation is made possible by a leaky T-junction dual-feeder using substrate-integrated waveguide (SIW) technology, creating a uniform wavefront that propagates through a truncated parallel-plate waveguide (PPW) section. In addition, a matching section based on an array of subwavelength printed patches is also included at the interface between the PPW and the grounded dielectric slab (GDS), while the AV section is positioned between the GDS and air region to improve antenna radiation. These features allow for an efficient and compact aperture, and findings are competitive compared to other relevant structures. For instance, the measured prototype demonstrated a peak realized gain (RG) of 17.5 dBi at 18.6 GHz, as well as high radiation efficiency and sidelobe levels (SSLs) of about −10 dB. This makes the SWA suitable for high data rate downlink communications when nondeployable designs are required on CubeSats, for example, or wherever a low-profile, simple, and planar antenna is needed with radiation directly at endfire.