A Varactor Electrically Tunable Microstrip Filter

Abstract

The invention discloses a varactor electrically-adjustable micro-strip filter. The varactor electrically-adjustable micro-strip filter comprises an input micro-strip line, a first resonator, a second resonator, a third resonator, a fourth resonator and an output micro-strip line, wherein the first resonator and the fourth resonator are opened outwards and are arranged in parallel in a mirror image manner; the adjacent parts of the first resonator and the fourth resonator form magnetic coupling; the second resonator and the third resonator are opened inwards, arranged in parallel in a mirror image manner and positioned above the first resonator and the fourth resonator; the adjacent parts of the second resonator and the third resonator form electric coupling; and the input micro-strip line and the output micro-strip line are positioned below the first resonator and the fourth resonator respectively and are arranged in parallel in a mirror image manner. By adoption of the magnetic coupling and electric coupling cross coupling structure, the filter has the ellipse-like function characteristics and has transmission zero point on the sideband, so that the filter has good rectangular coefficient and improved filtering performance.

Description

technical field [0001] The invention relates to the technical field of signal processing in the electronics industry, and in particular to a variable capacitance tube electrically adjustable filter. Background technique [0002] Electrically tunable filters are used in occasions where frequency changes, especially in the field of radar detection, to filter signals, so as to obtain a relatively pure spectrum and improve the anti-interference ability of the system. Electrically tunable filters are generally classified into two types: Yttrium Iron Garnet (YIG for short) electrically tunable filters and varactor electrically tunable filters. YIG electric tunable filter has a high quality factor, but due to the influence of hysteresis effect, its tuning speed is slow, so it cannot be applied to frequency agility occasions. The tuning speed of the varactor electronically tuned filter is fast, which can meet the needs of agile frequency conversion, and a high quality factor can be...

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Problems solved by technology

[0004] In the process of realizing the present invention, the applicant realizes that the following technical defects exist in the prior art: the existing varactor electric tuning filter usually adopts Butterworth synthesis or Chebyshev synthesis, and the design scheme square coefficient of these filters is not good, and there is no Steep edges, so the filtering effect on sidebands is not good, so it cannot meet the requirements in occasions with high requirements for sideband suppression

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