All-Frequency Absorptive CL Dual-Band BPF With Complementary Lossy Bandstop Branches
Yifan Zhang, Yongle Wu, Huiting Yu, Weimin Wang
Abstract
In this brief, input-/two-port all-frequency absorptive dual-band bandpass filters (BPFs) based on complementary duplexer architecture are proposed for the first time. The design consists of a simple coupled-line (CL) based dual-band BPF section and auxiliary dual-band bandstop filter (BSF) sections with resistively terminated absorptive stubs. The dual-band BPF can transmit spectral energy in two passbands with good in-band filtering response, while the out-of-band RF-signal energy can be absorbed by auxiliary BSF sections, which indicates all-frequency absorption from dc. The impedance of the absorptive stub and the value of the resistor can be independently adjusted to enhance the absorption. The operational foundations and explicit design equations are discussed and derived. Good agreements between the simulated and measured results verify the design theory.