A cryogenic metamaterial antenna platform with high radiation efficiency across the Ka-band

High-efficiency radio-frequency antennas operating at millimeter-wave frequen cies are essential for emerging satellite and high-capacity communication systems, yet their performance is often constrained by conductor losses, thermal insta bility and limited reconfigurability. These challenges become more pronounced in the Ka-band, where conventional metallic antennas suffer from reduced radi ation efficiency and increased sensitivity to environmental variations. Here we present a cryogenic metamaterial antenna platform that achieves high radiation efficiency across the Ka-band by integrating superconducting radiating elements with engineered metamaterial structures. The platform exploits the suppressed ohmic loss of high-temperature superconductors under cryogenic operation and employs sub-wavelength metamaterial unit cells to control electromagnetic radia tion characteristics over a broad frequency range. Experimental characterization demonstrates radiation efficiencies exceeding 90% from 20 to 40 GHz, sta ble performance under cryogenic temperatures between 4.2 K and 77 K, and robust operation after thermal cycling and vacuum testing. Array-level mea surements further show improved gain uniformity and reduced mutual coupling compared with conventional metallic antenna implementations. This cryogenic metamaterial antenna platform provides a scalable hardware approach for high efficiency Ka-band operation and offers opportunities for next-generation satellite communications and cryogenic radio-frequency electronic systems.