Small ultra-wideband bandpass filter with notch performance

Abstract

The invention relates to a small ultra-wideband bandpass filter with a notch performance. The whole filter is made of microstrip lines. A microstrip structure comprises three layers which are an upper-layer microstrip structure, a middle-layer dielectric substrate and lower-layer grounded metal respectively. The upper-layer microstrip structure comprises an input feeder line, an output feeder line, a parallel coupled microstrip line, a metal through hole, an open circuit branch line and two short circuit branch lines; the two short circuit branch lines are connected to two ends of the parallel coupled microstrip line respectively and used for generating transmission zeros at two ends of a filter pass band, so that the selectivity of the ultra-wideband filter is enhanced; and the position of each transmission zero can be changed by adjusting the length of each short circuit branch line. The frequency band and bandwidth of a notch can be flexibly changed by adjusting parameters such as the line width, the length and the like of the open circuit branch line. According to the filter, the pass band range can be ensured to cover the whole ultra-wide frequency band and interfering frequency components in the frequency band can be pointedly inhibited; and the filter has the characteristics of simple and compact structure and excellent performance.

Description

technical field [0001] The invention belongs to the field of microwave and millimeter wave technology, in particular to a small ultra-wideband band-pass filter with notch characteristics. Background technique [0002] In 2002, the Federal Communications Commission of the United States lifted the ban on the ultra-wideband (UWB) related frequency bands located at 3.1-10.6 GHz. With the rapid development of ultra-wideband wireless communication technology, higher requirements are put forward for ultra-wideband wireless communication electronic equipment. High performance and miniaturization have become an inevitable trend in the development of ultra-wideband wireless communication systems. In the past ten years, due to the advantages of simple structure and miniaturization, ultra-wideband filters with microstrip structure have become the main direction of research, and various forms of ultra-wideband filters have emerged. [0003] The ultra-wideband characteristics of the filt...

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Problems solved by technology

[0003] The ultra-wideband characteristics of the filter are realized by cascading a high-pass filter and a low-pass filter. This filter is easy to implement, but due to the high- and low-pass cascading, the filter size is large and not compact enough; the traditional quarter-wavelength The short-circuit stub bandpass filter has the advantages of wide operating bandwidth and simple structure, but the out-of-band suppression ability of this filter is poor. To improve the selectivity of this filter, it is necessary to increase the number of

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