A Novel Bandpass Filtering Switch with Reconfigurable Notched Band

In this paper, a novel filtering switch with three operating states has been proposed. The proposed structure consists of two coupling paths, a multi-mode bandpass filter (BPF) and an E-shaped notched band structure. A new transmission zero (TZ) can be introduced through the source load coupling structure. PIN diodes are loaded at both ends of the branches of the multi-mode resonator and the branches of the notched band structure to switch different operating modes. The measured results show that the dual-band bandpass filter (DB-BPF) mode is centered at 2.35/3.23 GHz with 3-dB fractional bandwidth (FBW) of 10.2%/19.8%, and the minimal insertion isolation within the passband of 1.8/1.28 dB. The single-band bandpass filter (SB-BPF) mode is centered at 2.9 GHz, and the insertion loss (IL) is lower than 2.3 dB with FBW of 46.9%. The all-stop filter (ASF) mode has an attenuation better than 27 dB from 1 GHz to 7 GHz. Simulated results and measured results show good agreement.