Planar CQ (Cascade Quadruplet) band-pass filter

Abstract

The invention relates to a planar CQ (Cascade Quadruplet) band-pass filter which is made on a double-sized copper-coated micro-strip plate by a mode of a printed circuit board. An input end feeding head port 1 for inputting an electromagnetic wave signal, an output end feeding head port 2 for outputting the electromagnetic wave signal, a first port feeding line, a second port feeding line, a first half-wavelength micro-strip resonator, a fourth half-wavelength micro-strip resonator, a second quarter-wavelength micro-strip resonator, a third quarter-wavelength micro-strip resonator and a grounding through hole are respectively made on the same surface of the double-sized copper-coated micro-strip plate, and a copper-coated grounding plate is arranged on the other surface of the micro-strip plate. The planar CQ band-pass filter is formed by cascading the two half-wavelength resonators and the two quarter-wavelength resonators, so that the filter can have simple controlled functions of electric coupling and magnetic coupling when the filter has small volume; crossed coupling is introduced among the resonators, two transmission zero points can be generated at the two sides of a pass band of the filter, the frequency selectivity and out-of-band rejection of the filter are improved, and the planar CQ band-pass filter has the advantages of good frequency selectivity, low insertion loss, small volume and a simple structure.

Description

technical field [0001] The invention relates to a planar bandpass filter in the form of a microstrip line, in particular to a planar CQ bandpass filter, which can meet the design requirements of high frequency selectivity, low insertion loss, small size, simple structure and low cost. Background technique [0002] Radio frequency / microwave filters are an indispensable part of modern microwave relay communication, satellite communication, wireless communication and electronic countermeasure systems, and are also the most important and most technical microwave passive components. Among them, the band-pass filter is one of the important components in the circuit system, and its performance determines the working quality of the system to a large extent. The bandpass filter mainly works in the RF front end of the communication system, and is used to pass useful signals in a certain frequency range with low loss, while attenuating frequency components in other frequency ranges to ...

AI Technical Summary

Problems solved by technology

However, in some structures, due to the use of half-wavelength resonator structures, the filter volume is too large, which is not conducive to integration

In addition, although the quarter-wavelength resonator structure reduces the filter volume, it will complicate the design of the coupling structure

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