2026/3/2

【基础射频器件创新论文】

A Compact Third-Order Cross-Coupled BPF Based on SISL Photonic Crystals

Abstract—This paper leverages the advantages of substrate integrated suspended line (SISL) and photonic crystals to propose a novel third-order cross-coupled band-pass filter (BPF) characterized by compactness and self-packaging. By altering the structural size of the photonic crystal, the slow-wave and bandgap effects can be flexibly adjusted in SISL structure. An effective balance can be archived among compact size, filtering performance, and insertion loss—since reducing size tends to significantly increase loss. Electrical and magnetic couplings serve as cross-coupling mechanisms to realize a cascaded trisection (CT) topology, which introduces a transmission zero (TZ) on the left of the passband. To validate this design, a compact third-order cross-coupled BPF with a center frequency of 4.658 GHz was fabricated and measured. The results show good agreement with simulations and demonstrate an upper out-of-band rejection exceeding 30 dB. The overall circuit size is 0.39λ_g × 0.22λ_g × 0.06λ_g.

Siyu Yang(博士生杨思雨), Qianyin Xiang*, Longchuan Liu, and Quanyuan Feng, A Compact Third-Order Cross-Coupled BPF Based on SISL Photonic Crystals，IEEE Microwave and Wireless Technology Letters，DOI: 10.1109/LMWT.2026.3670613.