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A Miniaturized Broadband Electrically Adjustable Cavity Filter

A cavity filter and electric tuning technology, which is applied in the direction of waveguide devices, circuits, electrical components, etc., can solve the problems of inaccurate frequency modulation, inability to maintain, small adjustable range, etc., to achieve tuning range, small radiation loss, The effect of reducing complexity

Active Publication Date: 2019-03-26
XIDIAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the initial performance of the tunable filter is relatively poor, mainly in the small adjustable range and large size.
During the entire tuning process, good passband performance cannot be maintained, and since mechanical or magnetic materials have been used for tuning, the filter has problems such as slow tuning speed and inaccurate frequency modulation.
[0004] In 2013, S.Fouladi, F.Huang et al published "High-Q narrowband tunable comblinebandpass filters using MEMS capacitor banks and piezomotors”, proposed an electrically adjustable coaxial cavity bandpass filter, which uses a radio frequency micro-electromechanical capacitor group loaded outside the cavity, and realizes a six-level narrow-band adjustable bandpass through the radio frequency micro-electromechanical system RF-MEMS control circuit The filter has the characteristics of compact structure and fast tuning speed. The filter works in the 2.634GHz to 2.59GHz frequency band, and the tuning range is only 44MHz. It has the disadvantages of too small tuning range and large volume

Method used

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  • A Miniaturized Broadband Electrically Adjustable Cavity Filter
  • A Miniaturized Broadband Electrically Adjustable Cavity Filter
  • A Miniaturized Broadband Electrically Adjustable Cavity Filter

Examples

Experimental program
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Effect test

Embodiment 1

[0020] In recent years, wireless communication has developed rapidly, and various communication services have emerged in different frequency bands. Especially in FM communication systems such as radar and electronic countermeasures, it is necessary to support multi-band and multi-mode reconfigurable RF front-ends to cover various communications. System data transfer. The tunable RF filter device is one of the core key devices of the reconfigurable RF front-end, which is responsible for specific frequency selection or specific frequency suppression. Therefore, it is of great significance to study tunable RF filter devices with high unloaded figure of merit, wide adjustable range, high tuning speed, high-frequency selection characteristics and miniaturization. Tunable filters are mainly divided into two types: mechanical tuning and electrical tuning. The mechanically tuned filter has the advantages of high no-load quality factor and wide adjustable range, but has the disadvanta...

Embodiment 2

[0024] The overall composition and structure of the miniaturized broadband electric cavity filter are the same as those in Embodiment 1. The square inner cavity 22 at the open end of the resonator 2 of the present invention has a cutout section on one side of the bottom, and the width of the cutout section is 0.5mm-2mm. , see Fig. 2, if there is no such cut section, the electric field is mainly concentrated on the outside of the metal wall at the open end of the resonator 2, and the electric field inside the square inner cavity 22 is very weak, and the tuning screw 4 extends into the space between the inside of the square inner cavity 22 and the inner cavity wall The capacitance value of the capacitor is very small, which has little influence on the frequency of the resonator 2, and cannot play the role of fine-tuning the frequency. And have this notch section, make rectangular body 21 and the square cavity 22 that is arranged on its upper end actually form SIR stepped impedanc...

Embodiment 3

[0026] The overall composition and structure of the miniaturized broadband electronically tuned cavity filter are the same as those in Embodiment 1-2, see image 3 , the L-shaped metal branch is loaded on the bottom of the open circuit end of the resonator 2. The L-shaped branch is equivalent to an open circuit branch, which is equivalent to a parallel capacitance C. The loading of the L-shaped metal branch makes the length of the resonator L 2 unchanged, increased With the value of the capacitance C in the middle denominator, the resonant frequency f is lowered, and miniaturization is realized. The resonant frequency of each level of resonator will shift due to the difference in the surrounding environment. By adjusting the length of the L-shaped branch 3, the resonant frequency of each level of resonator can be calibrated to the designed center frequency. See figure 2 .

[0027] In this example, the square inner cavity 22 at the open circuit end of the resonator 2 has a sl...

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Abstract

The invention discloses a minimal broadband electric tunable cavity filter which solves the problem that a conventional electric tunable filter can not realize tuning in broadband and the size is large. The structure includes five-stage cascade resonators, a square inner cavity is arranged in the open circuit end of each-stage of resonator, a rectangular notch is arranged on one side of the bottom, and an L-shaped branch is loaded on the open circuit end of the resonator to reduce size. One end of a tuning screw is screwed in the square inner cavity, and the other end passes through a dielectric substrate and electrically connected with the center of a metal sheet on the dielectric substrate. The metal sheet and a grounding metal ring are connected sequentially through four capacitor-pad-PIN switches, and each stage of resonator realizes group selected loading for the four capacitors to realize resonant frequency tuning. PIN switches in the same capacitor of the five resonators share a dc offset voltage source to control the on / off of the four voltage sources, thereby realizing rapid frequency modulation of the filter. Tuning in broadband is realized, and the size is small. Tuning in broadband is possible, the minimal broadband electric tunable cavity filter as a basic element of a microwave circuit is applicable to the front section of radio frequency of a wireless communication system.

Description

technical field [0001] The invention belongs to the technical field of microwave filters, and in particular relates to an electric tuning filter, in particular to a miniaturized broadband electric tuning cavity filter, which can be used in a radio frequency front end of a wireless communication system. Background technique [0002] In recent years, wireless communication has developed rapidly, and various communication services have emerged in different frequency bands. Especially in FM communication systems such as radar and electronic countermeasures, it is necessary to support multi-band and multi-mode reconfigurable RF front-ends to cover various communications. System data transfer. The tunable RF filter device is one of the core key devices of the reconfigurable RF front-end, which is responsible for specific frequency selection or specific frequency suppression. Therefore, it is of great significance to study tunable RF filter devices with high unloaded figure of mer...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01P1/208
CPCH01P1/208
Inventor 吴边郭泳欣夏磊徐扬许梅
Owner XIDIAN UNIV