Four-order microstrip band-pass filter with diagonal coupling box type topological structure

Abstract

The invention belongs to the technical field of microwaves, and particularly relates to a four-order microstrip band-pass filter with a diagonal coupling box type topological structure. The filter comprises three isosceles right triangle patch resonators, a stepped impedance microstrip line resonator and input and output feeder lines, wherein the three isosceles right triangle patch resonators arearranged side by side in a stepped shape and have short-circuited right-angle ends; the stepped impedance microstrip line resonator is positioned above the three isosceles right triangle patch resonators with short-circuited right-angle ends; and gaps exist among the three isosceles right triangle patch resonators with the short-circuited right-angle ends, and gaps exist between the stepped impedance microstrip line resonator and the three isosceles right triangle patch resonators with the short-circuited right-angle ends. The filter not only can realize the characteristics of on-demand configuration of two limited transmission zeros, including asymmetric frequency response, approximate elliptical response and linear phase response, but also can realize product miniaturization.

Description

technical field [0001] The invention belongs to the field of microwave technology, in particular to a fourth-order microstrip band-pass filter with a diagonal coupling box topology. Background technique [0002] As a frequency-selective device, microwave filters are widely used in front-end circuits of communication systems. With the rapid development of wireless communication technology, the communication system puts forward higher and higher requirements on the weight, volume, integration and electrical performance of the RF front-end circuit. [0003] In order to improve the selectivity of the passband of the filter, cross-coupling paths are added between non-adjacent resonators, thereby realizing finite transmission zeros (finite transmission zeros, FTZs) on both sides of the passband of the filter. [0004] A third-order filter can be implemented based on a traditional delta-element coupling topology, and an FTZ can be implemented that produces an FTZ above the passban...

AI Technical Summary

Problems solved by technology

For the simulation model that has been built, changing the response type requires remodeling, which is cumbersome and increases time costs.

[0006] In order to realize a filter with a limited transmission zero position that can be configured on demand, a combination of a double-mode square ring and a single-mode resonator is used to realize a box-type topology microstrip bandpass filter, such as the literature "Q.Liu, D.Zhou and D. Zhang, "Generalized Chebyshev function bandpass filters in box-like topologies based on the properties of dual-mode loop microstrip resonator," IET Microwaves, Antennas & Propagation, vol.13, no.10, pp.1515-1521, 14 8 2019." But The diagonal coupling strength is not easy to control, and the square ring resonator occupies a large size, which is not conducive to the miniaturization of the filter

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