阅读说明：本技术 一种不同物理温度下室内目标的毫米波发射率测量方法 (Method for measuring millimeter wave emissivity of indoor target at different physical temperatures ) 是由 胡飞 苏金龙 胡演 于 2019-09-30 设计创作，主要内容包括：本发明公开了一种不同物理温度下室内目标的毫米波发射率测量方法,包括将待测目标和黑体目标设置于同一室温下,使得所述待测目标和所述黑体目标的物理温度相同；构建不同亮温的室内均匀辐射环境,依次将金属目标、待测目标和黑体目标置于其中；利用辐射计分别对同一位置的金属目标、待测目标、黑体目标进行测量,得到第一电压、第二电压和第三电压；利用第一电压、第二电压和第三电压进行差值分析,得到待测目标的发射率。本发明通过对待测目标加热至指定温度,并使黑体目标也保持在相同温度下进行测量获取目标在不同物理温度下的发射率,不受外部环境的限制。(The invention discloses a method for measuring millimeter wave emissivity of an indoor target at different physical temperatures, which comprises the steps of arranging a target to be measured and a blackbody target at the same room temperature, so that the physical temperatures of the target to be measured and the blackbody target are the same; constructing indoor uniform radiation environments with different brightness temperatures, and sequentially placing a metal target, a target to be detected and a black body target in the indoor uniform radiation environments; respectively measuring a metal target, a target to be measured and a black body target at the same position by using a radiometer to obtain a first voltage, a second voltage and a third voltage; and performing difference value analysis by using the first voltage, the second voltage and the third voltage to obtain the emissivity of the target to be measured. The target to be measured is heated to the specified temperature, and the black body target is also kept at the same temperature to be measured to obtain the emissivity of the target at different physical temperatures, so that the method is not limited by the external environment.)

1. A method for measuring millimeter wave emissivity of indoor targets at different physical temperatures is characterized by comprising the following steps:

(1) setting the target to be measured and the blackbody target at the same room temperature T₁Then, enabling the physical temperatures of the target to be measured and the blackbody target to be the same;

(2) construction of a light temperature of T₂The metal target, the target to be detected and the black body target are sequentially placed in the indoor uniform radiation environment;

(3) respectively measuring a metal target, a target to be measured and a black body target at the same position by using a radiometer to obtain a first voltage, a second voltage and a third voltage;

(4) and performing difference value analysis by using the first voltage, the second voltage and the third voltage to obtain the emissivity of the target to be measured.

2. The measurement method according to claim 1, wherein the step (4) is implemented in a specific manner as follows:

and subtracting the first voltage from the second voltage to obtain a first difference value, subtracting the first voltage from the third voltage to obtain a second difference value, and dividing the second difference value by the first difference value to obtain the emissivity of the target to be measured.

3. The measurement method according to claim 1, wherein the step (2) is realized in a specific manner as follows:

the wave-absorbing material is fully paved in the direction which can be observed by the radiometer in an indoor uniform radiation environment, and the temperature of the wave-absorbing material is controlled.

4. The measurement method according to claim 1, characterized in that the main beam of the radiometer is projected completely on a metal target, a target to be measured or a black body target.

5. The measurement method of claim 4, wherein the metal target, the target to be measured, and the blackbody target are the same size.

6. The method of measurement according to claim 1, wherein the room uniform radiant light temperature is different from the physical temperature of the blackbody target, T₂≠T₁。

7. The measurement method according to claim 1, wherein when an included angle between the antenna of the radiometer and the target to be measured changes, the emissivity of the target to be measured at the corresponding angle also changes.

8. The method according to claim 7, wherein the angle between the antenna of the radiometer and the target is the angle between the normal vector of the plane of the target and the opposite direction of the normal vector of the antenna aperture of the radiometer.

9. The measurement method according to claim 1, wherein after rotating the radiometer, steps (3) to (4) are performed to obtain the emissivity of the target to be measured under different polarizations.

Technical Field

The invention belongs to the technical field of passive microwave remote sensing and detection, and particularly relates to a method for measuring millimeter wave emissivity of an indoor target at different physical temperatures.

Background

All natural and artificial substances spontaneously radiate electromagnetic energy to space in the form of electromagnetic waves when the physical temperature is higher than absolute zero, and a millimeter wave radiometer receives the electromagnetic signals to remotely sense and detect a target, and the technology is generally called as passive millimeter wave radiometry technology. Millimeter wave radiometry has the advantages of all-time, quasi-all-weather operation, concealment, good penetrability, etc., and thus has been applied to fields such as atmospheric remote sensing, ocean monitoring, soil and vegetation remote sensing, agricultural detection, security inspection, etc.

The millimeter wave radiometer receives millimeter wave radiation of an interested scene through the antenna, the radiation intensity of the millimeter wave radiometer is corresponded to through the value of the output voltage, and further, through a calibration process, the output voltage of the radiometer is converted into radiation brightness and temperature, and millimeter wave radiation measurement is achieved. Factors influencing spontaneous millimeter wave radiation of a substance in a scene are various, and the property, structure, size and the like of the substance influence the state of the spontaneously radiated electromagnetic wave. The difference of the factors causes the difference of the radiated electromagnetic waves to be displayed in the millimeter wave radiation brightness temperature, so that the target of interest is detected and identified.

It is also a difficult point for the acquisition of the information of the object to be measured to be the hotspot of the current research. The emissivity is a basic parameter for reflecting the millimeter wave radiation characteristic of a substance and is also a key parameter for distinguishing the material category, and the millimeter wave radiation capability of the substance can be accurately judged by measuring the emissivity.

Currently, the target brightness temperature, the ambient brightness temperature and the target physical temperature are usually measured outdoors in a direct or indirect manner, and emissivity calculation is performed by combining the results. However, this type of method does not allow emissivity measurement in rainy weather. The chinese patent application, entitled "method for measuring emissivity of target based on output voltage of radiometer" (application No. 201810472195.8, application date: 2018.05.16), requires that the physical temperatures of the target to be measured and the black body target are consistent during the measurement process, but the physical temperatures of the target to be measured and the black body target are difficult to be consistent under the sun exposure. In summary, outdoor weather conditions are complex and variable, and are often unsuitable for emissivity measurement.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide a method for measuring the millimeter wave emissivity of an indoor target at different physical temperatures, and aims to solve the problem that the environment is uncontrollable in the measurement of the emissivity of the outdoor target.

In order to achieve the above object, the present invention provides a method for measuring millimeter wave emissivity of indoor targets at different physical temperatures, comprising the following steps:

(1) setting the target to be measured and the blackbody target at the same room temperature T₁Then, enabling the physical temperatures of the target to be measured and the blackbody target to be the same;

(2) construction of a light temperature of T₂The metal target, the target to be detected and the black body target are sequentially placed in the indoor uniform radiation environment;

(3) respectively measuring a metal target, a target to be measured and a black body target at the same position by using a radiometer to obtain a first voltage, a second voltage and a third voltage;

(4) and performing difference value analysis by using the first voltage, the second voltage and the third voltage to obtain the emissivity of the target to be measured.

Further, the specific implementation manner of the step (2) is as follows:

the wave-absorbing material is fully paved in the direction which can be observed by the radiometer in an indoor uniform radiation environment, and the temperature of the wave-absorbing material is controlled.

Further, the specific implementation manner of step (4) is as follows:

and subtracting the first voltage from the second voltage to obtain a first difference value, subtracting the first voltage from the third voltage to obtain a second difference value, and dividing the second difference value by the first difference value to obtain the emissivity of the target to be measured.

Further, the main beam of the radiometer is completely projected on a metal target, a target to be measured or a black body target.

Furthermore, the metal target, the target to be measured and the black body target have the same shape and size, and the metal target, the target to be measured and the black body target are located at the same position and have the same surface normal vector.

Further, the indoor uniform radiation environment brightness temperature is different from the physical temperature of the blackbody target, T₂≠T₁。

Furthermore, the included angle between the antenna of the radiometer and the target to be measured is the reverse included angle between the normal vector of the plane of the target to be measured and the normal vector of the antenna aperture surface of the radiometer, and when the included angle between the antenna of the radiometer and the target to be measured is changed, the emissivity of the target to be measured under different angles is obtained.

Through the technical scheme, compared with the prior art, the invention has the following beneficial effects:

1. the emissivity measuring method provided by the invention can obtain the emissivity of the target at different physical temperatures by heating the target to be measured to the specified temperature, keeping the blackbody target at the same temperature, and then measuring the blackbody target in indoor uniform radiation environments at different room temperatures;

2. the emissivity measuring method provided by the invention can be used for indoor measurement, is not limited by weather conditions, and can be suitable for more extreme environments.

Drawings

FIG. 1 is a schematic flow chart of a method for measuring millimeter wave emissivity of an indoor target at different physical temperatures according to the present invention;

fig. 2 is a schematic structural diagram of an indoor uniform radiation environment provided by the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

The emissivity is a basic parameter for reflecting the millimeter wave radiation characteristic of a substance and is also a key parameter for distinguishing the material category, and the microwave/millimeter wave radiation capability of the substance can be accurately judged by measuring the emissivity.

The invention provides a method for measuring millimeter wave emissivity of indoor targets at different physical temperatures, which comprises the following steps of:

(1) setting the target to be measured and the blackbody target at the same room temperature T₁Then, the physical temperatures of the target to be measured and the blackbody target are the same, i.e. T in this embodiment₁＝295K；

(2) Construction of a light temperature of T₂The metal target, the target to be measured and the black body target are arranged in the indoor uniform radiation environment, wherein T is arranged in the embodiment₂＝350K；

(3) Respectively measuring a metal target, a target to be measured and a black body target at the same position by using a radiometer to obtain a first voltage V₁A second voltage V₂And a third voltage V₃；

(4) Using a first voltage V₁A second voltage V₂And a third voltage V₃And performing difference analysis to obtain the emissivity of the target to be detected. The method specifically comprises the following steps:

applying a second voltage V₂Minus the first voltage V₁Obtaining a first difference value, and applying a third voltage V₃Minus the first voltage V₁Obtaining a second difference value, and dividing the first difference value by the second difference value to obtain the emissivity e of the target to be measured, wherein the formula is as follows:

e＝(V₂-V₁)/(V₃-V₁)

in this embodiment, the incident angle is 45 °, the polarization mode of the radiometer antenna is vertical polarization, and the radiometer is used for measurement, so that the first voltage 4.7V, the second voltage 4.1V and the third voltage 3.9V are obtained, and the vertical polarization emissivity e of the target to be measured at the incident angle of 45 ° at the physical temperature of 295K is obtained as (4.1-4.7)/(3.9-4.7) as 0.75.

Specifically, as shown in fig. 2, the specific implementation manner of step (2) is as follows:

the left side surface, the right side surface, the upper surface and the back surface of the object to be detected are fully paved with wave-absorbing materials, the wave-absorbing materials are externally insulated by foam, the wave-absorbing materials are heated by a heating sheet, and the physical temperature of the wave-absorbing materials is controlled to be 350K.

Specifically, the main beam of the radiometer is completely projected on a metal target, a target to be measured or a black body target, the metal target, the target to be measured and the black body target have the same shape and size, and the metal target, the target to be measured and the black body target are located at the same position and have the same surface normal vector.

Specifically, an included angle between the antenna of the radiometer and the target to be measured is an included angle between a normal vector of a surface where the target to be measured is located and a normal vector of a surface where the antenna of the radiometer is located, and when the included angle between the antenna of the radiometer and the target to be measured is changed, emissivity of the target to be measured under different angles is obtained.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.