Suspended stripline cross-coupled bandpass filter

Abstract

The invention discloses a cross-coupled bandpass filter with suspended strip lines, and mainly aims at solving the problem that a traditional filter cannot simultaneously achieve reduction of the insertion loss and miniaturization. The cross-coupled bandpass filter comprises a rectangular outer cavity (1), a suspended dielectric substrate (2), a Z-shaped input feeder (3), a Z-shaped output feeder (4), rectangular suspended strip line resonators (5) and U-shaped cross-coupled lines (6), wherein each of the Z-shaped input feeder (3) and the Z-shaped output feeder (4) comprises three vertical microstrip lines which are distributed on ports and the upper side and the lower side of the dielectric substrate respectively; the multiple stages of rectangular suspended strip line resonators are set into six stages which are the same in structure; each stage of rectangular suspended strip line resonator comprises two rectangular patches and metal through holes; the two rectangular patches are distributed on the upper surface and the lower surface of the dielectric substrate and are connected at one end of an open circuit through the metal through holes; and each U-shaped cross-coupled line comprises double side branches and an upper side branch which are distributed among the strip line resonators. By the cross-coupled bandpass filter with the suspended strip lines, the insertion loss and the circuit dimension of the filter can be reduced; miniaturization of the circuit is achieved; and the cross-coupled bandpass filter can be applied to a wireless communication system.

Description

technical field [0001] The invention belongs to a suspension stripline device, in particular to a cross-coupling bandpass filter, which can be used for a radio frequency front end of a wireless communication system. Background technique [0002] In the current practical application, the requirements for multi-frequency and multi-channel work in radar, microwave communication, mobile communication and other departments are becoming more and more common, and the requirements for separation frequency are also getting higher and higher, so a large number of microwave filters need to be used, especially It is a bandpass filter, which can filter out the signals on both sides of the passband, which can limit the radiation of high-power transmitters in the specified frequency band, and in turn can be used to prevent the receiver from being interfered with outside the working frequency band. In microwave and millimeter wave circuits, transmission lines such as microstrip lines and wa...

AI Technical Summary

Problems solved by technology

However, although this scheme has four transmission zero points, there is only one transmission zero point that can actually be controlled, and only the position is controllable, and the polarity is not controllable; at the same time, due to the existence of the "U"-shaped branch There is a relatively obvious glitch phenomenon between the passband of the bandpass filter and the controllable transmission zero, which affects the passband and out-of-band rejection characteristics

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