A High-Impedance Line Self-Packaged Low-Pass Filter Based on SISL Technique

This paper presents a novel self-packaged low-pass filter (LPF) based on the substrate-integrated suspended line (SISL) technique, employing a high-impedance line structure. The core circuit of the proposed LPF integrates three distinct transmission line technologies: stripline (SL), grounded coplanar waveguide (GCPW), and SISL. Leveraging these advanced techniques, the prototype LPF with a cutoff frequency (f0) of 3 GHz has been successfully designed and fabricated. Comprehensive measurements reveal that the LPF exhibits an insertion loss (S21) of greater than −0.74 dB within the pass-band, while maintaining a stop-band ranging from 5 GHz to 12.2 GHz, achieving a suppression level exceeding 15 dB. Additionally, the highest internal solid-line impedance reaches 110 Ω. Given its superior performance characteristics, the proposed LPF is highly suitable for application in radio frequency (RF) front-end systems, specifically for filtering and screening signals within designated frequency bands.