Dual-band filter

Abstract

The invention discloses a dual-band filter applied to the communication field. The dual-band filter comprises a medium substrate provided with a grounding through hole, a main circuit located on the upper surface of the medium substrate, and a metal floor located on the lower surface of the medium substrate. The main circuit is formed by concatenation of two dual-band resonators arranged in an axial symmetry mode, the two dual-band resonators are connected through the grounding through hole, and each dual-band resonator is connected with an input transmission line or an output transmission line. Each dual-band resonator comprises a low-impedance transmission line, an L-shaped short circuit high-impedance transmission line and an open circuit transmission line, wherein the L-shaped short circuit high-impedance transmission line and the open circuit transmission line are respectively connected on the low-impedance transmission line. The dual-band filter overcomes the defects that a traditional dual-band filter is complex in structure, large in size and the like, and has the advantages of being high in frequency selectivity, good in interband isolation performance, compact in structure and small in size, and center frequency and bandwidth can be controlled easily.

Description

technical field [0001] The invention belongs to the technical field of microwave communication, and in particular relates to a dual-band filter suitable for microwave and millimeter wave planar circuits. Background technique [0002] The rapid development of multi-band and multi-standard wireless communication systems puts forward higher design requirements for the frequency of multi-band bandpass filters. At present, there are many ways to realize dual-band bandpass filters. The more common structures and their existing problems are as follows: (1) Two sets of single-band resonances are connected in parallel to realize dual-band filters. The existing problems are An additional matching circuit is often required, and the structure is complex and bulky; (2) A dual-band filter is designed by introducing a transmission zero in the passband of a wideband bandpass filter, but the filter has a complex structure and is difficult to design; (3) The traditional half-wavelength stepp...

AI Technical Summary

Problems solved by technology

At present, there are many ways to realize dual-band bandpass filters. The more common structures and their existing problems are as follows: (1) Two sets of single-band resonances are connected in parallel to realize dual-band filters. The existing problems are An additional matching circuit is often required, and the structure is complex and bulky; (2) A dual-band filter is designed by introducing a transmission zero in the passband of a wideband bandpass filter, but the filter has a complex structure and is difficult to design; (3) The traditional half-wavelength stepped impedance resonator is used for dual-band filter design, but the passbands of the dual-band filter affect each other, making the design difficult and bulky

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