Dielectric loaded tunable filter and its design method, tunable duplexer

Abstract

The invention discloses a medium loading adjustable filter which comprises a rectangular waveguide, a tuning medium piece, and a driving mechanism. The cavity is divided into a plurality of resonant cavities by a set of partition walls arranged in the cavity and parallel to the E face, the wide edge pipe wall of one side of the rectangular waveguide is provided with at least one slit correspondingto the position of each resonant cavity, the slit is distributed along the bisector of the E face, and the length direction of the slit is parallel to the E face, the tuning medium piece is a comb-shaped structure with a set of comb teeth pieces, the length and the thickness of each comb tooth piece are the same, all the comb teeth pieces of the comb-shaped structure can be inserted into the cavity of the rectangular waveguide without friction through the slit at the same time, the number of the comb teeth pieces inserted into each resonant cavity is the same; and the driving mechanism is used for driving the tuning medium piece and adjusting the insertion depth. The invention further discloses a design method of the filter and an adjustable duplexer. According to the invention, the electrical performance is better, the structure is simpler, and the production cost is lower.

Description

Technical field [0001] The invention relates to a tunable filter, in particular to a medium-loaded tunable filter. Background technique [0002] Tunable filters are an important part of the microwave reconstruction system and are widely used in frequency hopping radios, electronic countermeasures, multi-function receivers, dynamic frequency allocation systems, etc. Common tunable filters are mostly implemented by means of radio frequency switches to control the loading capacitor, or piezoelectric capacitors. These tunable filters can only work in lower frequency bands. [0003] In recent years, due to the development of communication systems, tunable filters in the microwave frequency band have been widely required. In order to be able to meet the use of higher microwave frequency bands, the design method of radio frequency band tunable filters is obviously no longer applicable. In order to be able to design qualified tunable filters in the microwave frequency band, it is current...

AI Technical Summary

Problems solved by technology

But these two methods have disadvantages: 1. The filters themselves of these two forms of adjustable filters are all filters in the form of E-face metal diaphragm partitions. This is due to the thickness of the diaphragm at the input and output ends. Very thin, therefore, the bandwidth of this form of filter cannot be made very wide, and the metal diaphragm is easily damaged, which fundamentally limits the performance of these two adjustable filters; 2. The filter divides the resonant cavity between The partition wall adopts a diaphragm structure, resulting in the tuning mechanism can only be adjusted in half of the cavity, which limits the tuning range and results in a wide enough tuning bandwidth. According to reports, the adjustable bandwidth is only 2%-5%;3 , Out-of-band suppression, in-band insertion loss and in-band echo deteriorate seriously during the tuning process, and the bandwidth changes continuously with tuning

[0005] In addition, the biggest disadvantage of the NEC solution is that the dielectric sheet can only rotate 90 degrees at most, so the tuning is very sensitive. In order to reduce the sensitivity of tuning, NEC uses a reduction structure composed of multiple gears similar to a gearbox. This structure reduces tuning. However, the disadvantages of the deceleration structure are also very obvious. Firstly, the structure is complex, the volume is large and the cost is high. Secondly, due to the torsion problem of the deceleration structure, the motor must always be energized to maintain the locked state during the working process, which reduces the life of the motor. increase energy consumption

Huawei's solution uses a dielectric sheet to push flatly, but the push rod of the supporting medium cannot be made of metal, only a high-strength dielectric rod, which is easy to damage, and how to ensure the consistency of installation and the balance of the forward push when the motor is driven is also a problem. a big problem

[0006] Jiangsu Beifude Communication Technology Co., Ltd. provides a tunable filter that uses a stepping motor to drive a beryllium bronze diaphragm, which can be tuned in a wide range (patent number: ZL201521082510.4), but beryllium bronze contains The highly toxic metal beryllium is a banned material in many countries

Due to the current on the metal surface, if you want to reduce the leakage, you must put the tuning piece in good contact, so there will be a lot of friction, so that the motor cannot push the tuning piece, so the leakage problem of this solution is also very difficult to solve The problem

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