Reducing Antenna Leakage in Quasi-Monostatic Satellite Radar Using Planar Metamaterials

In an autonomous robotic space debris removal mission, an essential sensor used for navigation is an FMCW radar designed for close-range relative navigation. To achieve the required range performance, minimizing RF leakage between the transmitter (Tx) and receiver (Rx) antennas is essential for the accurate detection of the range and velocity of the targeted space debris. Antennas positioned above the metallic satellite front face are highly susceptible to RF leakage, primarily caused by surface current propagation and lateral waves traveling parallel to the platform. This study presents two lightweight, single-layer planar metamaterials—a novel compact electromagnetic bandgap (EBG) and a non-uniform high-impedance surface (HIS)—optimized to suppress both surface waves and interact with space waves within the 9.3–9.8 GHz frequency range. These designs address strict size, weight, and power (SWaP) constraints while ensuring compatibility with extreme space conditions and resistance to mechanical shocks. Experimental validation indicates that a minimum Tx/Rx isolation improvement of 10 dB is achieved using the HIS, and 20 dB is achieved using the EBG across the radar’s operational bandwidth (5%).