A novel dual-passband filter

Abstract

The present invention belongs to the technical field of microwave communication and provides a dual-passband filter suitable for microwave and millimeter wave planar circuits. The dual-passband filter includes a dielectric substrate provided with a grounding through hole, a main line on the upper surface of the dielectric substrate and a metal floor positioned below the dielectric substrate. The main line is formed by concatenation of two annular stepped impedance resonators which are distributed in axial symmetry. The two loading knot annular stepped impedance resonators are connected through a grounding through hole. The two annular stepped impedance resonators are respectively connected to an input feed line and an output feed line. The novel dual-passband filter is characterized in that the side of the ring of each annular stepped impedance resonator is embedded with an open circuit transmission line. The dual-passband filter solves the problem of miniaturization of a traditional dual-passband filter, and simultaneously has the characteristics of easy center frequency and bandwidth control, high frequency selectivity, good isolation between bands, a compact structure and a small size.

Description

technical field [0001] The invention belongs to the technical field of microwave communication, and specifically relates to a double-passband filter suitable for microwave and millimeter wave planar circuits. Background technique [0002] In the increasingly crowded spectrum resources and complex electromagnetic environment, communication systems have higher and higher requirements for filter miniaturization and high selectivity. And with the emergence of the multi-passband pattern, more and more transceiver systems must support multiple channels to work at the same time, so the advantages of multi-passband filters in spectrum resource utilization and frequency band compatibility are becoming more and more obvious. It can work in two or more required working frequency bands at the same time according to the requirements of the communication system, and filter out the interference signals of other frequency bands on the basis of being compatible with the existing communicatio...

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Problems solved by technology

[0003] There are many ways to realize the dual-passband filter at present, and the common structure and its existing problems are as follows: (1) carry out certain connection with two existing single-band filters to form the dual-passband filter, and its The problem is that an additional impedance matching network is often required, which increases the difficulty of circuit design; (2) By adding stub lines of different lengths on the basis of a band-stop filter, multiple The attenuation pole divides two passbands, but this method is highly targeted and poor in versatility; (3) a double passband filter is designed by introducing a transmission zero in the passband of a wideband bandpass filter, but The structure of the filter is complex and the design is difficult; (4) the traditional half-wavelength stepped impedance resonator is used to design the dual-passband filter, but the passbands of the dual-passband filter affect each other, and the design is difficult, and Big size

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