Dual-passband band-pass filter based on asymmetric coupling lines

Abstract

The invention provides a dual-passband band-pass filter based on asymmetric coupling lines. The filter comprises a dielectric substrate, a filter positioned on the upper surface of the dielectric substrate, and a metal grounding plate positioned on the lower surface of the dielectric substrate, the filter comprises an H-shaped multi-mode resonator with an improved center, asymmetric parallel coupling lines loaded on the left side and the right side of the multi-mode resonator, stepped impedance branches loaded on the upper side and the lower side of the multi-mode resonator, parallel three-line coupling lines composed of high impedance lines and the parallel coupling lines, and open circuit branches loaded on the lower side of a left port feeder line. According to the invention, under thestrong coupling effect of the multi-mode resonator loaded with a stepped impedance stub and the asymmetric coupling line structure, the selectivity of a passband is improved, and the size of the filter is reduced. The two passbands are low and adjustable in insertion loss, so the filter is good in out-of-band characteristic, compact in structure, low in cost, convenient to process and easy to integrate with other circuits.

Description

technical field [0001] The invention belongs to the technical field of microwave communication, and more specifically relates to a double-pass band-pass filter based on an asymmetric coupled line. Background technique [0002] With the rapid development of modern literature communication technology, more and more mobile communication, satellite communication, radar tracking and remote sensing technology need to rely on microwave and millimeter wave technology, which leads to an increasingly complex electromagnetic environment and ultimately makes spectrum resources more and more tense. [0003] Therefore, in order to effectively utilize more and more frequency channels, and to reduce the volume and weight of communication circuit equipment, the research of dual-band devices has attracted more and more attention. [0004] At present, the design methods for realizing dual-band filtering mainly include: [0005] 1. Use an external impedance matching network to cascade two band...

AI Technical Summary

Problems solved by technology

[0005] 1. Use an external impedance matching network to cascade two bandpass filters with different center frequencies, but this will increase the size and loss of the filter;

[0006] 2. Connect resonators with open or short-circuit stubs in series or in parallel in the broadband bandpass filter, so that a transmission zero point is generated in the passband, thereby obtaining high selectivity, but the design is complicated and the circuit area will be increased at the same time ;

[0007] 3. Using the high-order characteristics of the base-layer waveguide resonator can also design a dual-pass band-pass filter, but the filter is difficult to adjust and has poor flexibility

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