Microstrip band-pass filter

Abstract

The invention relates to the field of microwave and millimeter wave circuits, and discloses a microstrip band-pass filter, which comprises a substrate, input ports and a resonator group consisting ofresonators, wherein the resonator group is arranged on the substrate in a mirror symmetry manner, the input ports are respectively connected to the resonators at the two ends of the resonator group, and the input ports are connected to the resonators at the two ends of the resonator group. A folding resonator pair is arranged in the middle of the resonator group; the folding resonator pair comprises two folding resonators which are in mirror symmetry; the equivalent electrical length of each resonator and each folding resonator is a quarter wavelength, and the shape of each folding resonator can be changed according to actual conditions. According to the microstrip band-pass filter provided by the invention, at least one group of folding quarter-wavelength resonator pairs are embedded in the middle of a traditional interdigital microstrip band-pass filter, so that a transmission zero point is generated at the low end of a filter passband, and the out-of-band rejection capability of thelow end of the passband is further improved, and out-of-band rejection of the low pass-band end and the high pass-band end is promoted to be relatively symmetrical.

Description

technical field [0001] The invention relates to the field of microwave and millimeter wave circuits, in particular to a microstrip bandpass filter. Background technique [0002] Microwave filters play the role of filtering clutter in microwave integrated circuits. With the rapid development of wireless communication technology, the spectrum coverage of various applications is getting wider and wider, which puts forward higher and higher requirements for the out-of-band suppression ability of filters. [0003] The traditional interdigitated microstrip bandpass filter is widely used due to its advantages of small size and easy planar integration, but its out-of-band frequency response presents an asymmetric phenomenon of upturning at the low end and concave at the high end, resulting in a low passband. The problem of poor out-of-band rejection. Therefore, there are certain limitations in applications that require high out-of-band suppression at the low end of the passband. ...

AI Technical Summary

Problems solved by technology

like Figure 4 and Image 6 Shown is a traditional 6th-order interdigitated microstrip bandpass filter and its frequency response. There is no transmission zero at the low end of the passband, which makes the out-of-band rejection at the low end poor, showing an asymmetrical phenomenon of upturning at the low end and concave at the high end.

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