Engineering

Bandwidth (computing)

Materials science

Low-pass filter

Stub (electronics)

Planar

Computer graphics (images)

Literature

Telecommunications

Computer science

Antenna (radio)

Prototype filter

Multi-band device

Physics

Microstrip

Optics

Passband

Electronic engineering

Resonator

Fractional bandwidth

Topology (electrical circuits)

Dual (grammatical number)

Band-pass filter

Optoelectronics

Electrical engineering

IEEE Transactions on Circuits & Systems II Express Briefs

Based on a novel microstrip terminated cross-shaped resonator (TCSR), the dual-band bandpass filters (DB-BPFs) with fixed and reconfigurable bandwidths are proposed in this brief. In addition to the basic TCSR's three poles and four zeros, the extra four poles and three zeros can be introduced with the help of a pair of symmetrical parallel-coupled lines and open-ended stubs. Therefore, a planar DB-BPF with multiple transmission poles and zeros can be realized. To achieve the reconfigurable bandwidths, a capacitor is inserted into the basic TCSR's lower stub. It is found that the lower bandedge of the first passband can be tuned while the other three bandedges are kept unchanged. Two prototypes, including fixed-bandwidth filter (Filter I) with 3-dB fractional bandwidths (FBWs) of 20.8% and 17.3%, and reconfigurable-bandwidth filter (Filter II) with 3-dB FBW variation from 22.5% to 34.7% for the first passband and 19.8% for the second passband, are designed, fabricated, and experimentally characterized. The experimental characterizations of these two filters verify the proposed design.

Design of Dual-Band Bandpass Filters With Fixed and Reconfigurable Bandwidths Based on Terminated Cross-Shaped Resonators