A Self-Packaged Low-Loss and Compact SISL DBBPF With Multiple TZs

In this letter, a dual-band bandpass filter (DBBPF) with multiple transmission zeros (TZs) based on the substrate-integrated suspended line (SISL) technology platform is proposed. The DBBPF is designed by using a short-stub-loaded resonator and a pair of modified feed lines. The feed lines are special for exciting the circuit on G6, simultaneously forming the second passband and introducing TZs through input-output coupling. Particularly, the design adopts the patterned suspended substrate structure, and it shows loss reduction of 0.22 and 0.24 dB in two passbands. The implemented SISL DBBPF shows a low insertion loss of only 0.59 and 0.55 dB with the fractional bandwidths of 45.43% and 21.64% centered at 2.4 and 5.2 GHz, respectively.