Substrate integrated waveguide bandpass filter with wide stop-band characteristic

Abstract

The invention discloses a substrate integrated waveguide bandpass filter with a wide stop-band characteristic. The filter comprises a substrate integrated waveguide and a feed part, wherein the substrate integrated waveguide adopts rectangular substrate integrated waveguide cavities and is commonly defined by a plurality of metal through holes penetrating through a medium substrate and a metal patch on the upper surface of the medium substrate; four rectangular substrate integrated waveguide cavities with the same sizes and a distribution form like the Chinese character 'tian' are formed and comprise a first cavity, a second cavity, a third cavity and a fourth cavity in sequence from the beginning of an input end along the clockwise direction; the output end of the substrate integrated waveguide is connected with the fourth cavity; the feed part comprises a microstrip impedance transition line, an input end, an output end and a coplanar waveguide; the first cavity and the fourth cavity are respectively transited to the microstrip impedance transition lines at corresponding sides through the coplanar waveguide; the microstrip impedance transition lines on the outer sides of the first cavity and the fourth cavity are respectively connected with the input end and the output end. The whole structure of the filter is in an axisymmetric structure about a common side of the second cavity and the third cavity. The filter has the advantages of wide stop-band characteristic and smaller in-band return loss.

Description

a technical field [0001] The invention relates to the technical field of microwave filters, in particular to a substrate integrated waveguide bandpass filter with wide stopband characteristics. Two background technology [0002] The main implementation forms of microstrip filters include lumped elements and transmission line types, and the basic structures of transmission line filters include waveguides, coaxial lines, striplines, and microstrips. Coaxial microwave filters have the advantages of good electromagnetic shielding performance, low loss and small size, but when the operating frequency is high, there will be processing difficulties caused by too small physical size; waveguide microwave filters have low loss, The advantages of high quality factor and large power capacity, but its biggest disadvantage is its large size, which is not conducive to the miniaturization and integration of the system; the most common microstrip filter in planar circuits has the advantages ...

AI Technical Summary

Problems solved by technology

However, since the SIW structure often contains large metal planes and metallized vias, its own loss is scattered

The traditional directly cascaded substrate-integrated waveguide bandpass filter has unsatisfactory stopband characteristics; in order to improve the stopband characteristics, the transmission path is increased by cross-coupling the physical structure, but the structure of the cross-coupled filter is complex and difficult to implement

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