High‐Performance and Space‐Qualified L‐Band to Ka‐Band Up‐Converter Based on Hybrid Local‐Oscillator Architecture

This paper proposes a high‐reliability design for a space‐qualified L‐Ka (band) up‐converter used in millimeter‐wave communication systems. The design addresses key challenges related to phase noise, image rejection, output power, and environmental adaptability. It adopts a hybrid local‐oscillator (LO) structure that combines a direct digital synthesizer (DDS), a phase‐locked loop (PLL), and a frequency multiplier chain. Together with a double‐balanced mixer, a cavity filter, and a cascade switch, the system achieves excellent phase‐noise performance of −120 dBc/Hz@1 MHz and an image‐rejection ratio of at least 75 dB. For reliability, the system follows the space‐qualified processes and complies with the “six‐property” criteria. Measures such as derating, cavity‐based electromagnetic shielding, and thermally redundant power‐supply design extend the mean time between failures (MTBF) to 21,739 h. A modular architecture and remote intelligent monitoring further enable on‐orbit maintainability. Experimental and simulation results show that the proposed up‐converter outperforms existing reference designs in gain‐control accuracy, 1 dB compression point, spurious suppression, and other core metrics. Several performance indicators approach the international state of the art. This study provides an engineering‐ready solution for high‐reliability, space‐qualified millimeter‐wave equipment and contributes to improving system performance and autonomy in related applications.