Compact Leaky-Wave SIW Antenna with Broadside Radiation and Dual-Band Operation for CubeSats

This letter presents a substrate-integrated waveguide (SIW) antenna for CubeSat applications. The compact structure utilizes middle-point feeding and shorting walls to achieve broadside radiation in the far-field at two distinct frequencies. In particular, this dual-frequency behavior is related to the transition from a dominant leaky wave (LW) on the aperture at lower frequencies to more hybrid radiation (at higher frequencies) due to LW fields and structure resonance due to truncation. This response is generated by the shorting vias at the lateral ends of the SIW antenna. Given these conditions, the developed leaky-wave antenna (LWA) prototype is well matched ($|S_{11}|$ $\leq$ -10 dB) from 23.2 to 23.5 GHz and 24.8 to 25.2 GHz with realized gains of 8 and 6 dBi, respectively. Maximum efficiency (including the connector) is around 87%. Such dual-frequency operation could enable up-link and down-link operation in the K-band. Overall dimensions of the antenna are 2 $\lambda _0$ × 2.6 $\lambda _0$ (at the lower frequency). Possible placement on CubeSats can be underneath solar panels, thus increasing the available surface area for solar power harvesting. Also, to the best knowledge of the authors, no similar dual-frequency SIW-LWA has been previously reported.