X/Ku-Band Shared-Aperture Phased Array With Low-Frequency Ratio and High Isolation

This article presents an X-/Ku-band shared-aperture phased array antenna featuring a low-frequency ratio of 1.2 and achieving over 30 dB of isolation between the X-band (10.7–12.7 GHz) and Ku-band (13.7–14.5 GHz). To address high mutual coupling challenges inherent in low-frequency ratio systems, the design integrates two key innovations: an isolation cavity and a grounded resonant patch (GRP). First, the isolation cavity leverages resonant behavior to form a standing wave, effectively blocking low-frequency energy. Second, the GRP forms a resonant circuit to suppress high-frequency coupling, ensuring minimal inter-band interference. A fabricated prototype demonstrated exceptional performance, with a ±45° scanning range and 70% aperture efficiency for both bands. These results highlight the antenna’s superior isolation and efficiency, making it a practical solution for compact hybrid satellite communication systems.