Multi-functional Ultrawideband BPFs with Reconfigurable Absorptive and Tunable Attenuation Characteristics

This paper presents a new class of wideband RF co-designed bandpass filters (BPFs) with two distinct reconfigurable modes of operation. It is based on cascaded BPF stages, each one formed by a resistively-terminated asymmetric coupled-line section and two resistively-connected stubs that are at its RF input/output ports. Reconfigurability is achieved by readily altering the values of the resistive terminations. Specifically in its Mode 1 of operation, it functions as a bandpass filter-attenuator with variable attenuation levels. In the second mode of operation, Mode 2, it operates as a highly-selective absorptive BPF. To validate the proposed concept, two multi-functional example BPF configurations (one-stage and two-stage) were designed, built and tested.