A dual-band-pass balanced filter with double-layer structure

Abstract

The invention discloses a dual-band bandpass balanced filter with a double-layer structure, which includes an upper structure and a lower structure, the upper structure includes a first dielectric substrate and a first microstrip line structure, and the lower structure includes a second dielectric substrate and a second A microstrip line structure, the first microstrip line structure is arranged on the top surface of the first dielectric substrate, and the second microstrip line structure is arranged on the bottom surface of the second dielectric substrate; the first microstrip line structure includes a first resonator, The first step impedance branch, the first port feeder and the second port feeder, the second microstrip line structure includes the second resonator and the second step impedance branch, the first step impedance branch is loaded on the first resonator The center of the second step impedance branch is loaded on the center of the second resonator; a metal sheet is arranged between the upper structure and the lower structure, and a gap is opened on the metal sheet, and the upper structure is coupled with the lower structure through the gap. The filter of the invention has good in-band performance, strong out-of-band suppression ability and excellent common-mode suppression performance.

Description

technical field [0001] The invention relates to a band-pass balanced filter, in particular to a dual-frequency band-pass balanced filter with a double-layer structure, which belongs to the field of wireless communication. Background technique [0002] Wireless communication technology is playing an increasingly important role in real social life. As an important part of the wireless communication field, the demand for band-pass filters is also increasing. Dual-band band-pass filter (DB-BPF) has received great attention due to its wide application in modern wireless communication systems. Balanced filters have excellent anti-interference ability, so they are widely used in advanced wireless communication systems. Dual-band bandpass balanced filter is one of the current research hotspots. At present, most balanced filters need to introduce additional lumped parameter elements to suppress common-mode interference. Recently, the slot-line structure is mostly used in the desig...

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Problems solved by technology

[0006] 3) In 2012, Yen-Ju Lu et al. published a paper titled "A Differential-Mode Wideband Bandpass Filter With Enhanced Common-Mode Suppression Using Slotline Resonator" on IEEE Microwave and Wireless Components Letters to design a broadband balanced filter using slot line resonators The bandwidth of the differential mode -10dB echo reflection reaches 105%, and the common mode rejection reaches more than 47.5dB, but the size of this structure is too large

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