CN-121978058-A - Capacitive type refractometer based on variable capacitor

CN121978058ACN 121978058 ACN121978058 ACN 121978058ACN-121978058-A

Abstract

The invention provides a capacitance type reflectometer based on a variable capacitor, which relates to the technical field of atmospheric waveguide parameter detection and comprises a capacitance detection circuit, a frequency mixing module, a filtering circuit and a data processing module which are sequentially connected, wherein a capacitance sensor adopting the variable capacitor is arranged in the capacitance detection circuit, the capacitance value of the capacitance sensor is related to an entering gas, the capacitance detection circuit is used for detecting and acquiring a detection electric signal influenced by the capacitance value of the variable capacitor, the frequency mixing module is used for mixing the detection electric signal, the filtering circuit is used for filtering the mixed electric signal to generate a stable oscillation signal, the data processing module is also connected with a temperature compensation module, the temperature compensation module is used for detecting and acquiring the temperature electric signal, and the data processing module is used for performing digital-to-analog conversion and data processing on the stable oscillation signal and the temperature electric signal to obtain the refractive index.

Inventors

SHI SHUIE
LI MENGYAO
QU LILI
WANG JIAWEI
LIU LINLIN
WANG YUMIAO

Assignees

河南师范大学

Dates

Publication Date: 20260505
Application Date: 20260309

Claims (8)

1. A variable capacitance-based capacitive reflectometer, comprising: The device comprises a capacitance detection circuit, a frequency mixing module, a filter circuit and a data processing module which are sequentially connected, wherein a capacitance sensor adopting a variable capacitance is arranged in the capacitance detection circuit, and the capacitance value of the capacitance sensor is related to the entering gas; The detection circuit is used for detecting and acquiring detection electric signals influenced by the capacitance value of the variable capacitance, the detection electric signals are mixed through the mixing module, and the mixed electric signals are filtered through the filtering circuit to generate stable oscillation signals; The data processing module is also connected with a temperature compensation module, the temperature compensation module is used for detecting and obtaining a temperature electric signal, and the data processing module is used for carrying out digital-to-analog conversion and data processing on the stable oscillation signal and the temperature electric signal to obtain a corrected refractive index.
2. The capacitive refractometer of claim 1, wherein the capacitive refractometer comprises, The capacitance sensor adopts a variable capacitance structure with a cylindrical capacitance and a variable pole pitch, positive electrodes and negative electrodes which are alternately arranged in sequence are arranged in the capacitance sensor, wherein the positive electrodes are connected through connecting wires to form the positive electrode of the capacitance sensor, the negative electrodes are connected through another connecting wire to form the negative electrode of the capacitance sensor, the contact area and the distance between the positive electrode and the negative electrode are adjusted to adjust the initial value of the capacitance, and when gas enters the interval between the positive electrode and the negative electrode, the capacitance sensor outputs an electric signal corresponding to the gas.
3. The capacitive refractometer of claim 1, wherein the capacitive refractometer comprises, The outside of the capacitive sensor is provided with a copper sheet, an opening is arranged at the corresponding position of the capacitive sensor on the copper sheet, and a latticed copper sheet is arranged at the opening.
4. The capacitive refractometer of claim 1, wherein the capacitive refractometer comprises, The capacitance detection circuit adopts a capacitance feedback type three-section oscillator.
5. The capacitive refractometer of claim 1, wherein the capacitive refractometer comprises, The filtering circuit adopts a 5-order LC resonant circuit, wherein the filtering circuit comprises 5 reactance elements which are sequentially connected in series, and corresponding loop capacitances are connected in parallel between each reactance element, and the loop capacitances are connected in parallel.
6. The capacitive refractometer of claim 1, wherein the capacitive refractometer comprises, An operational amplifier is also connected between the filter circuit and the data processing module, wherein the operational amplifier is a decoupled single-power operational amplifier bias circuit.
7. The capacitive refractometer of claim 1, wherein the capacitive refractometer comprises, The capacitive sensor, the mixing module and the filter circuit are all arranged on the PCB.
8. The capacitive refractometer of claim 1, wherein the capacitive refractometer comprises, The temperature compensation module adopts a temperature compensation circuit based on an LM35DT sensor.

Description

Capacitive type refractometer based on variable capacitor Technical Field The invention relates to the technical field of atmospheric waveguide parameter detection, in particular to the field of measurement of atmospheric refractive index, and particularly relates to a capacitance type refractometer based on a variable capacitor. Background The atmospheric refractive index is a key physical parameter slightly greater than 1 that describes how slow the propagation velocity of an electromagnetic wave in the atmosphere is relative to vacuum. It varies with temperature, air pressure, humidity, and height and position. The atmospheric refractive index, which is a seemingly tiny physical quantity, plays an extremely important role in many scientific and engineering fields because it directly affects the propagation path and characteristics of electromagnetic waves (light, radio waves, microwaves, radar waves, etc.) in the atmosphere, such as beyond-the-horizon propagation, i.e., under certain atmospheric conditions (such as the presence of a strong reverse temperature layer or humidity gradient), the gradient of the refractive index with altitude is large enough that the degree of bending down of the radio waves or radar waves exceeds the effect of the curvature of the earth. This may allow the signal to travel far beyond the normal line of sight distance, i.e. "beyond line of sight". This is critical to radar detection range, design of the radio communication link and interference prediction. Currently, the devices for measuring the atmospheric refractive index mainly comprise a microwave refraction rate meter and a 59 type sonde, but the microwave refraction rate meter is inconvenient to arrange when measuring the atmospheric refractive index at high altitude, and the 59 type sonde has advantages in stability, especially the smoothness of humidity data, is still partially researched and introduced so far, however, the device has short plates in high-layer precision, response speed and data consistency. Therefore, accurate measurement, modeling and prediction of the atmospheric refractive index and its changes are critical for scientific research, engineering applications, national defense security and daily life. The method is bridge parameters for connecting electromagnetic wave propagation physics with a plurality of fields such as atmospheric science, space information technology, communication engineering and the like. Disclosure of Invention In view of the above, the present invention proposes a capacitive refractometer based on a variable capacitor to solve the above-mentioned problems of the prior art. In order to achieve the above object, the present invention provides a capacitive reflectometer based on a variable capacitor, comprising: The device comprises a capacitance detection circuit, a frequency mixing module, a filter circuit and a data processing module which are sequentially connected, wherein a capacitance sensor adopting a variable capacitance is arranged in the capacitance detection circuit, and the capacitance value of the capacitance sensor is related to the entering gas; The detection circuit is used for detecting and acquiring detection electric signals influenced by the capacitance value of the variable capacitance, the detection electric signals are mixed through the mixing module, and the mixed electric signals are filtered through the filtering circuit to generate stable oscillation signals; The data processing module is also connected with a temperature compensation module, the temperature compensation module is used for detecting and obtaining a temperature electric signal, and the data processing module is used for carrying out digital-to-analog conversion and data processing on the stable oscillation signal and the temperature electric signal to obtain a corrected refractive index. The capacitance sensor comprises a cylindrical capacitor, a variable capacitance structure, a positive electrode, a negative electrode, an electric signal and a gas inlet, wherein the cylindrical capacitor is connected with the variable capacitance structure through a variable pole pitch, the variable capacitance structure is formed by combining a cylindrical capacitor with a variable pole pitch, positive electrodes and negative electrodes which are sequentially and alternately arranged are arranged in the capacitance sensor, the positive electrodes are connected through connecting wires to form the positive electrode of the capacitance sensor, the negative electrodes are connected through another connecting wire to form the negative electrode of the capacitance sensor, the contact area and the interval between the positive electrodes and the negative electrodes are adjusted to adjust the initial value of the capacitance, and when the gas enters the interval between the positive electrodes and the negative electrodes, the capacitance sensor outputs the electric signal corresponding to the gas. Optiona