A tunable bandpass filter

Abstract

A tunable bandpass filter, including a filter body, is placed in an external magnetic field. The main body of the filter includes a resonant cavity, an upper substrate and a lower substrate arranged in the resonant cavity, a radio frequency input terminal provided at one end of the resonant cavity and a radio frequency output terminal at the other end; Both are equipped with microstrip lines, the RF input terminal is connected to the microstrip line of the lower substrate, and the RF output terminal is connected to the microstrip line of the upper substrate; both the upper substrate and the lower substrate are provided with a YIG substrate, and the YIG substrate is connected to the microstrip line. The YIG substrate includes a GGG substrate connected with a microstrip line and a YIG film arranged on the top surface of the GGG substrate, and there is a predetermined distance between the YIG film surfaces of the upper and lower YIG substrates. Through the structural design of the resonant cavity, and using the YIG substrate formed by the YIG film and the GGG substrate, the center frequency of a certain frequency range can be adjusted, and it has the characteristics of simple structure and easy assembly.

Description

technical field [0001] The invention belongs to the technical field of radio frequency microwaves, and in particular relates to a band-pass filter with adjustable center frequency. Background technique [0002] Yttrium iron garnet (YIG) magnetically tuned filter, referred to as YTF, is a filter with tunable center frequency. In recent years, due to the demand for miniaturization in electronic countermeasures and test equipment, YIG magnetic modulation filters can be used as preselectors to replace the switching filter banks in receivers. By adjusting the size of the magnetic field and changing the center frequency of the filter, interference can be suppressed Signal, through the useful signal, so as to realize the small volume characteristics of the entire electronic system. In addition to the advantages of fast tuning within a wide frequency band of several octaves, the YIG magnetically tuned filter also has the advantages of high tuning linearity and high out-of-band reje...

AI Technical Summary

Problems solved by technology

However, in order to realize a filter with good performance, YIG balls need to go through a complicated polishing process to obtain small balls with precise dimensions, extremely low eccentricity and optical precision; at the same time, it is necessary to adjust the orientation of multiple YIG balls to achieve The easy axis is parallel to achieve synchronous tuning, which requires a complex tuning device to fine-tune the ball

Therefore, it is not easy to achieve mass production of products using YIG balls as harmonic oscillators

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