A High-Isolation Self-Packaged Filter Array Using a 3-D Hybrid Integrated Shielding Cavity

A self-packaged and 3D hybrid integrated shielding cavity filter array that achieves > 50 dB adjacent-channel isolation in an ultra-compact multilayer PCB footprint (39.60 mm × 39.60 mm × 1.82 mm) is presented, eliminating the need for bulky external metal shielding cavities. The design integrates four X/Ku-band bandpass filters (centered at 7.75 GHz, 8.75 GHz, 9.75 GHz, and 10.75 GHz) using a 3D hybrid isolation strategy that synergistically combines orthogonal polarization, vertical layer segregation, a gold-ribbon shielding fence, and a central metallic island for cavity-mode suppression. Measured results demonstrate that the in-band insertion loss is below 7.0 dB, the stopband rejection exceeds 40 dBc across all channels, and the inter-channel isolation is better than 50 dB over 7.5-8 GHz, 8.5-9 GHz, 9.5-10 GHz, and 10.5-11 GHz ranges. Full-wave simulations corroborate the measurements, validating the efficacy of the proposed architecture. This approach offers a scalable, low-cost, and highly integrable solution for dense microwave front-ends in next-generation phased-array radars and software-defined radio systems.