Microstrip switchable diplexer based on dual-mode stub-loaded stepped-impedance resonators with three operating states

• Published in: Electronics letters 2019-10, Vol.55 (22), p.1188-1190
• Main Authors: Chen, C.-F, Chen, R.-Y, Zhou, K.-W, He, Y.-H
• Format: Article
• Language: English
• Subjects: distributed coupling structure; dual‐mode stub‐loaded stepped‐impedance resonators; input coupled‐line; microstrip filters; microstrip switchable diplexer; Microwave technology; multiplexing equipment; p‐i‐n diodes; resonator filters; SL‐SIR; structural parameters; switching control; three‐state switchable diplexer; two‐pole filtering response
• ISSN: 0013-5194; 1350-911X; 1350-911X
• DOI: 10.1049/el.2019.2204

A new three-state switchable diplexer based on dual-mode stub-loaded stepped-impedance resonators (SL-SIRs) has been proposed. The three-state diplexer comprised six SL-SIRs with a distributed coupling structure. By appropriately adjusting the structural parameters of the SL-SIRs, a two-pole filtering response can be implemented at each channel passband. In addition, three p-i-n diodes, which were connected to the T-junction of the input coupled-line, were used to control the switching between the three operating states. Moreover, each operating state can be switched independently. For the purpose of demonstration, a three-state switchable diplexer was designed and fabricated using microstrip technology. The simulated results were consistent with the measured results, which indicate that the proposed switchable diplexer not only has a good in-band performance but also provides good isolation of better than 25 dB between output channels.