Compact sext‐band bandpass filter based on single multimode resonator with high band‐to‐band isolations

Abstract

On the basis of a single multimode resonator (MMR), a miniaturised microstrip sext‐band bandpass filter (BPF) with high band‐to‐band isolations has been presented. The proposed MMR is an stepped impedance resonator (SIR) with one short‐circuited stub loaded in the middle and two identical open‐circuited stubs located at two sides. Transmission poles (TPs) and transmission zeros (TZs) can be excited when the electrical lengths of two open stubs increase. The TZs introduced by open stubs separate the TPs into multiple groups; therefore, the design of a sext‐band BPF becomes available. Moreover, two input/output tapped branches and radical stub‐loaded short‐circuited lines are treated as perturbation structures in order to increase design freedoms for improving filter performance. Good agreement between simulated and measured results validates the design method.

Quad‐ and sext‐band bandpass filter based on multimode resonator utilizing SIRs‐loaded tapered‐line

“…There is an increasing need for high‐performance multiband filter in modern wireless communication system and numerous designs in view of multimode resonator are proposed . Certain quint‐ or sext‐band bandpass filter designs utilizing multimode resonator in conjunction with mixed electric and magnetic coupling have been presented . Two multiband bandpass filters are reported, whereas six pairs of SIR are employed to implement sext‐band .…”

“…Two multiband bandpass filters are reported, whereas six pairs of SIR are employed to implement sext‐band . However, a great deal of resonators in previous works are built up by SIR with or without loaded stubs, which introduces discontinuities and causes higher‐order modes or radiation loss unavoidably. Since tapered‐line has served as an important item in the application of impedance transformation, to the best of our knowledge, there are hardly any multiband designs using tapered‐line.…”

Compact quint‐band Bandpass Filter design in a rigorous manner utilizing multimode stub‐loaded taper

“…There is an increasing demand for high‐performance multiband filter in modern wireless communication system and numerous designs in view of MMR are proposed . On account of MMR and mixed electric magnetic coupling scheme, certain quint‐ or sext‐band BPFs have been presented . Some multiband filters are reported, whereas uniform or asymmetric SIR is employed to implement these passbands.…”

“…1 On account of MMR and mixed electric magnetic coupling scheme, certain quint-or sext-band BPFs have been presented. [2][3][4] Some multiband filters are reported, 5,6 whereas uniform or asymmetric SIR is employed to implement these passbands. However, resonators in previous works are built up by SIRs at the cost of introducing discontinuities and radiation loss.…”

Sext‐band bandpass filter with compactness based on cascading stage of SIRs

“…, whereas six pairs of SIRs are employed to implement sext‐band at the cost of absolutely vast dimensions. Certain quint‐ or sext‐band bandpass filter designs utilizing multimode resonator in conjunction with mixed electric magnetic coupling have been presented . However, extra structures like radical stub‐loaded short‐circuited lines or loaded‐stubs with stub‐to‐stub coupling are needed for improving isolation between multimode, which increases physical size.…”