Tunable filter

Abstract

The invention relates to a tunable filter, which is characterized in that each cavity of the filter is internally provided with a resonant column to form a structure close to a coaxial resonant cavity, the side wall of the quasi-coaxial structure is provided with at least two gaps which surround the resonant column and are arranged in the axial direction, a dielectric sheet extends into the resonant cavity through the gaps to realize the adjustment of the passband frequency range of the tunable filter. The tunable filter is suitable for the lower frequency band of microwave point-to-point communication, and the volume of the filter can be reduced through the loading of the resonant columns and the quasi-coaxial cavity loading technology. The band cross coupling is realized by a double-layer dielectric sheet structure which is matched with the cavity arrangement. In the whole tuning range of the tunable filter, the distance between a transmission zero point realized by cross coupling and a passband can be basically kept unchanged, the passband width of the filter can be basically kept unchanged, and the echo of the filter can be kept at a relatively good level at the same time. Thetransmission zero point is realized by adopting cross coupling, and the out-of-band rejection degree of the filter can be greatly increased.

Description

technical field [0001] The invention relates to the field of adjustable microwave devices, in particular to an adjustable filter. Background technique [0002] In recent years, due to the needs of the development of communication systems, tunable filters in the microwave frequency band have a wide range of needs. Such as Huawei, ZTE, NEC, Ericsson, etc. have carried out in-depth research in this field. Among them, NEC started research in this area as early as 2005, and published relevant research results in 2010. [0003] At present, the methods used in the microwave field mainly include the following: 1. The medium rotation method proposed by NEC Corporation of Japan to realize the tunable filter (patent number: WO2010150815A1), using a piece of high dielectric constant medium as the tuning mechanism, through the stepping motor Drive a shaft to rotate and turn the medium sheet to tune, so as to achieve an adjustable effect. 2 Huawei's tunable filter (WO2016095165A1) uses...

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Problems solved by technology

2 Huawei's tunable filter (WO2016095165A1) uses screw debugging to realize the tunable filter. At that time, the screw method itself had problems such as insufficient stability, electromagnetic leakage, and production difficulties.

For the point-to-point communication system in the 6G or 7 / 8GHz frequency band, if the above method is still used, the size of the adjustable filter / duplexer will be too large, resulting in the system being too bulky

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