CN-121978424-A - Multichannel microwave diagnosis system based on double microwave sources

CN121978424ACN 121978424 ACN121978424 ACN 121978424ACN-121978424-A

Abstract

The invention discloses a multi-channel microwave diagnosis system based on double microwave sources, which comprises two independent microwave sources, a power divider, a frequency doubler, a band-pass filter, two directional couplers and a transmitting antenna, wherein the two independent microwave sources are used for generating microwave signals with different frequencies, each microwave source can generate a signal with a specific frequency, the power divider (used as a beam combiner) is used for combining the generated microwave signals with different frequencies into a composite signal, the frequency doubler is used for doubling the input composite signal into a series of spaced microwave signals, the band-pass filter is used for retaining the microwave signals with an effective frequency band, and finally the microwave signals with the effective frequency band are transmitted into plasmas through the transmitting antenna and used for detecting the microwave signals. The system can solve the problems that a plurality of microwave sources are needed in a superposition scheme of a plurality of microwave sources, so that the cost of the microwave sources is high, and the power distribution and adjustment of a plurality of signals are complex.

Inventors

ZHOU CHU
SHI WENXIANG
LIU ADI
ZHUANG GE

Assignees

中国科学技术大学

Dates

Publication Date: 20260505
Application Date: 20260210

Claims (6)

1. A multi-channel microwave diagnostic system based on dual microwave sources, the system comprising two independent microwave sources, a power divider, a frequency doubler, a bandpass filter, two directional couplers, and a transmitting antenna, wherein: the microwave signals of different frequencies are generated by two independent microwave sources, each microwave source being capable of generating a signal of a specific frequency, expressed as And Wherein ; Combining the generated microwave signals with different frequencies into a composite signal by a power divider, the frequency being expressed as The frequency difference of the two microwave signals is ; Frequency doubling of an input composite signal using a frequency doubler to a series of intervals Is a microwave signal of (2); a band-pass filter is used for retaining microwave signals of an effective frequency band; And finally, transmitting the microwave signals of the effective frequency band into plasma through a transmitting antenna to be used for detecting the microwave signals.
2. A dual microwave source-based multi-channel microwave diagnostic system according to claim 1, wherein the composite signal is passed through a frequency doubler prior to use The band-pass filter and the attenuator remove the impurity peak and control the power to meet the input power requirement of the frequency doubler.
3. The dual microwave source-based multi-channel microwave diagnostic system according to claim 1, wherein the band-pass filter is used for retaining the microwave signals in the effective frequency band, and the specific process is as follows: the band-pass filter is formed by cascading a high-pass filter band and a low-pass filter band, and the microwave signals of an effective frequency band are reserved by utilizing the frequency characteristics of a capacitor element passing high frequency, low frequency and a resistor element passing low frequency, high frequency and low frequency, so that the set frequency band is ensured The signals in the frequency band are smoothly transmitted, and the signals outside the frequency band are greatly attenuated.
4. The dual microwave source-based multi-channel microwave diagnostic system according to claim 1, wherein the directional coupler is a three-port passive microwave device for proportionally taking out the forward or reverse partial signals in the main transmission path; the first directional coupler is used for reserving a path of transmitting signals as reference signals of a secondary I/Q mixing part, and the secondary I/Q mixing part is called a reference path; the second directional coupler is used to receive the returned Doppler back scattered signal and is called the receiving path in the secondary I/Q mixing section.
5. The dual microwave source-based multi-channel microwave diagnostic system according to claim 1, wherein the frequency difference between the two microwave sources is varied by varying the frequency difference between the two microwave sources Adjusting the frequency interval between the microwave signals of each channel; Wherein the frequency of the two microwave sources is different Equal to the frequency interval of each microwave signal, and the frequencies of the multiple microwave signals are used for Is a tolerance and at the same time comprises And Is a positive integer arithmetic progression of (c), expressed as: ; And is also provided with ; K represents the kth microwave signal.
6. The dual microwave source-based multi-channel microwave diagnostic system according to claim 1, wherein the power distribution between the multi-channel microwave signals after the frequency multiplier is adjusted by varying the power distribution between the two microwave sources; Wherein in particular by increasing Output power of (2) Increasing the frequency Less than the reference frequency By conversely increasing the power of the transmitted signal Output power of (2) Increasing the frequency Greater than the reference frequency Is provided.

Description

Multichannel microwave diagnosis system based on double microwave sources Technical Field The invention relates to the technical field of microwave diagnosis, in particular to a multichannel microwave diagnosis system based on double microwave sources. Background The design of single channel doppler backscatter (Doppler Backscattering, DBS) diagnostic systems is relatively simple, focusing mainly on determining the proper operating frequency and selecting the mode of fixed frequency or swept frequency operation, but single channel DBS can only measure the density fluctuation and velocity fluctuation of the plasma at a single radial position, cannot measure the radial distribution of the radial electric field, etc., and lacks radial coverage capability. The multi-channel measurement scheme can be divided into two types in principle, one is a multiple microwave source superposition scheme, which generates microwave signals of different frequencies by using multiple independent signal sources or single sideband modulators (SSBs). Each signal source or modulator may generate a signal of a particular frequency, which is then combined by a combiner into a composite signal for transmission. The method has the advantages that the system is simple in structure and easy to realize, each signal source can be independently adjusted, maintenance and replacement are convenient, however, mutual interference among the signal sources, frequency and power distribution need to be carefully managed, and meanwhile, the scheme needs a plurality of signal sources, so that the cost of the signal sources is high. The second is to design a multi-frequency generation scheme that generates signals of multiple frequencies from a single signal source, a common multi-frequency generation method includes a comb spectrum generator scheme, which has the advantage of generating clean signals and is relatively simple. However, this method has the problem of unstable power distribution between frequency peaks, requires periodic adjustment to maintain uniformity of frequency peaks, a VCO modulation scheme which can achieve precise control of multi-channel frequencies but requires complex modulation and control circuitry, and a double sideband modulator (DSBM) double frequency scheme which can produce signals with specific frequency shifts but requires optimization to reduce spurious signals and improve purity of the signals. In view of this, the present invention has been made. Disclosure of Invention The invention aims to provide a multi-channel microwave diagnosis system based on double microwave sources, which solves the technical problems in the prior art. The system can solve the problems that the cost of the microwave source is high due to the fact that a plurality of microwave sources are needed in a multi-microwave source superposition scheme, and the power distribution and adjustment of a plurality of signals are complex. The invention aims at realizing the following technical scheme: a dual microwave source based multi-channel microwave diagnostic system comprising two independent microwave sources, a power divider, a frequency doubler, a bandpass filter, two directional couplers, and a transmitting antenna, wherein: the microwave signals of different frequencies are generated by two independent microwave sources, each microwave source being capable of generating a signal of a specific frequency, expressed as AndWherein; Combining the generated microwave signals with different frequencies into a composite signal by a power divider, the frequency being expressed asThe frequency difference of the two microwave signals is; Frequency doubling of an input composite signal using a frequency doubler to a series of intervalsIs a microwave signal of (2); a band-pass filter is used for retaining microwave signals of an effective frequency band; And finally, transmitting the microwave signals of the effective frequency band into plasma through a transmitting antenna to be used for detecting the microwave signals. Compared with the prior art, the system provided by the invention can solve the problems that a plurality of microwave sources are needed in a superposition scheme of a plurality of microwave sources, so that the cost of the microwave sources is high, and the power distribution and adjustment of a plurality of signals are complex, can simultaneously measure turbulence, the polar rotation speed of plasma and the like at a plurality of radial positions, and can calculate the radial distribution of a radial electric field. Drawings In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the description of the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort f