CN102435324A - Temperature-changing source device of linearly-polarized microwave radiometer - Google Patents

Abstract

The invention relates to a temperature-changing source device of a linearly-polarized microwave radiometer. The temperature-changing source device comprises a cold source, a heat source and a polarization network, wherein central points of the cold source, the heat source and the polarization network are located on the same horizontal plane; the cold source is used for providing a low-temperature brightness temperature to output; the heat source is used for providing a high-temperature brightness temperature to output; the polarization network is used for outputting a changed linearly-polarized microwave radiation brightness temperature through changing a rotating angle of the polarization network; the cold source and the heat source are respectively arranged at two sides of the polarization network; and the center of the polarization network and the center of a test antenna of the microwave radiometer are located at a central axis of the system. The temperature-changing source device is characterized in that: the polarization network is rotatably arranged by taking the central axis of the plane, on which the polarization network is arranged, as a center. The temperature-changing source device of the linearly-polarized microwave radiometer has the advantages that: the microwave radiometer is calibrated, a microwave radiometer receiver is debugged, the linearity and the flexibility of the microwave radiometer are tested, the temperature-changing time is short and the test is convenient.

Description

A kind of linear polarization microwave radiometer alternating temperature source apparatus

Technical field

The present invention relates to microwave radiometer alternating temperature source apparatus, particularly a kind of linear polarization microwave radiometer alternating temperature source apparatus.

Background technology

Microwave radiometer is a kind of microwave remote sensor of passive type, and this microwave comprises millimeter wave and submillimeter wave.Can round-the-clock, round-the-clock the space meteorological datas such as global atmosphere temperature and humidity, moisture content, rainfall amount that obtain; And geophysical parameters such as marine surface temperature, ocean wind field, soil moisture, in atmospheric exploration and oceanographic observation, have vital role.

No matter be ground, airborne and satellite-borne microwave radiometer, the time all need the alternating temperature source,, measure the indexs such as sensitivity and the linearity of calibration coefficient, the system of system, so that satisfy the quantification request for utilization so that receiver is debugged or calibrated in debugging and calibration.

Traditional microwave radiometer alternating temperature source is made up of calibration body and attemperating unit, reaches the purpose of alternating temperature output through control calibration body physical temperature.The shortcoming of this mode is that the calibration body is long to the another one adjustment time from a temperature, generally needs 30 minutes～60 minutes, the bad control of temperature.Especially under hot vacuum environment, need regulate several hrs sometimes and can make the calibration temperature stable and even.

Summary of the invention

The objective of the invention is to, make microwave radiometer calibration and test fast, and improve microwave radiometer measuring accuracy and calibration precision.

For realizing the foregoing invention purpose, the present invention proposes a kind of linear polarization microwave radiometer alternating temperature source apparatus.

Described a kind of linear polarization microwave radiometer alternating temperature source apparatus, this alternating temperature source apparatus comprises: central point is positioned at low-temperature receiver, thermal source and the polarization grid on the same surface level;

Described low-temperature receiver is used to provide the output of low temperature brightness temperature;

Described thermal source is used to provide the output of high temperature brightness temperature;

Described polarization grid is used for exporting the bright temperature of linear polarization microwave radiation of variation through changing the polarization grid anglec of rotation;

Described low-temperature receiver and described thermal source are divided into the both sides of described polarization grid, and the center of the center of described polarization grid and microwave radiometer test antenna is all on the central axis of system; It is characterized in that,

Described polarization grid is the rotatable setting in center with the central shaft perpendicular to polarization grid place face.

The temperature of described cold/heat source keeps fixed value.

The main body of described cold/heat source is a black matrix.

Described polarization grid is rounded.

Described low-temperature receiver is placed perpendicular to the central axis of system, and described thermal source is parallel to the central axis of system to be placed, and described polarization grid is arranged on the angular bisector of radiating surface 90 angles of radiating surface and described thermal source of described low-temperature receiver.

The brightness temperature T of described linear polarization microwave radiometer output _h, T _vWith the bright temperature T of thermal source _HOT, the bright temperature T of low-temperature receiver _COLDAnd the relational expression between the polarization grid anglec of rotation θ is:

$\left[\begin{array}{c}{T}_v\\ T_h\end{array}\right]=\left[\begin{array}{cc}\frac{2{\cos }^2\mathrm{\θ}}{1+{\cos }^2\mathrm{\θ}}& \frac{{\sin }^2\mathrm{\θ}}{1+{\cos }^2\mathrm{\θ}}\\ \frac{{\sin }^2\mathrm{\θ}}{1+{\cos }^2\mathrm{\θ}}& \frac{2{\cos }^2\mathrm{\θ}}{1+{\cos }^2\mathrm{\θ}}\end{array}\right]\·\left[\begin{array}{ccc}{r}_{\left|\right|}& t_{\left|\right|}& L_{\left|\right|}\\ r_{\⊥}& t_{\⊥}& L_{\⊥}\end{array}\right]\·\left[\begin{array}{c}{T}_{\mathrm{HOT}}\\ T_{\mathrm{COLD}}\\ T_G\end{array}\right]---\left(1\right)$

In the formula (1), T _GThe physical temperature of expression metal grill; r _||, t _||, and L _||The reflection coefficient of representing metal grill when the mesh lines direction is parallel with the polarization of ele direction respectively, transmission coefficient and ohmic loss; r _⊥, t _⊥, L _⊥Represent reflection coefficient, transmission coefficient and ohmic loss when vertical respectively.

When described polarization grid is the perfect polarization grid, the brightness temperature T of described linear polarization microwave radiometer output _hAnd T _vWith the bright temperature T of thermal source _HOT, the bright temperature T of low-temperature receiver _COLDAnd the relational expression between the polarization grid anglec of rotation θ is:

$\left[\begin{array}{c}{T}_v\\ T_h\end{array}\right]=\left[\begin{array}{cc}\frac{2{\cos }^2\mathrm{\θ}}{1+{\cos }^2\mathrm{\θ}}& \frac{{\sin }^2\mathrm{\θ}}{1+{\cos }^2\mathrm{\θ}}\\ \frac{{\sin }^2\mathrm{\θ}}{1+{\cos }^2\mathrm{\θ}}& \frac{2{\cos }^2\mathrm{\θ}}{1+{\cos }^2\mathrm{\θ}}\end{array}\right]\·\left[\begin{array}{c}{T}_{\mathrm{HOT}}\\ T_{\mathrm{COLD}}\end{array}\right]---\left(2\right).$

The invention has the advantages that; The linear polarization microwave radiometer alternating temperature source apparatus that the present invention proposes reaches the purpose of this equipment output brightness temperature of control through the rotary polarization grid; Thereby realize a plurality of brightness temperature points of output; Thereby can realize to Calibration of Microwave Radiometer, microwave radiometer receiver debugging, the microwave radiometer linearity and sensitivity test, and the alternating temperature time is short, convenient test.

Description of drawings

The vertical view of Fig. 1 linear polarization microwave radiometer alternating temperature source apparatus;

The polarize front elevation of grid of Fig. 2;

Fig. 3 linear polarization microwave radiometer alternating temperature source output brightness temperature and polarization grid anglec of rotation graph of a relation.

Embodiment

Below in conjunction with accompanying drawing and specific embodiment linear polarization microwave radiometer alternating temperature source apparatus of the present invention is carried out detailed explanation.

Fig. 1 is the vertical view of linear polarization microwave radiometer alternating temperature source apparatus, and Fig. 2 is the front elevation of polarization grid.Illustrated in figures 1 and 2, the present invention is made up of low-temperature receiver, thermal source and polarization grid.The brightness temperature T that exports among Fig. 2 _hAnd T _vWith heat source temperature T _HOT, sink temperature T _COLDAnd the relation between the polarization grid anglec of rotation is suc as formula shown in (3):

$\left[\begin{array}{c}{T}_v\\ T_h\end{array}\right]=\left[\begin{array}{cc}\frac{2{\cos }^2\mathrm{\θ}}{1+{\cos }^2\mathrm{\θ}}& \frac{{\sin }^2\mathrm{\θ}}{1+{\cos }^2\mathrm{\θ}}\\ \frac{{\sin }^2\mathrm{\θ}}{1+{\cos }^2\mathrm{\θ}}& \frac{2{\cos }^2\mathrm{\θ}}{1+{\cos }^2\mathrm{\θ}}\end{array}\right]\·\left[\begin{array}{ccc}{r}_{\left|\right|}& t_{\left|\right|}& L_{\left|\right|}\\ r_{\⊥}& t_{\⊥}& L_{\⊥}\end{array}\right]\·\left[\begin{array}{c}{T}_{\mathrm{HOT}}\\ T_{\mathrm{COLD}}\\ T_G\end{array}\right]---\left(3\right)$

Wherein, T _HOTAnd T _COLDBe respectively the bright temperature of thermal source and low-temperature receiver, T _GIt is the physical temperature of metal grill.r _||, t _||, and L _||Be respectively reflection coefficient, transmission coefficient and the ohmic loss of mesh lines direction metal grill when parallel with the polarization of ele direction.r _⊥, t _⊥, L _⊥Reflection coefficient when being respectively vertical, transmission coefficient and ohmic loss.Because the polarization characteristic of polarization grid is good among the present invention, can treat as the perfect polarization grid, formula (3) can be simplified an accepted way of doing sth (4) so:

$\left[\begin{array}{c}{T}_v\\ T_h\end{array}\right]=\left[\begin{array}{cc}\frac{2{\cos }^2\mathrm{\θ}}{1+{\cos }^2\mathrm{\θ}}& \frac{{\sin }^2\mathrm{\θ}}{1+{\cos }^2\mathrm{\θ}}\\ \frac{{\sin }^2\mathrm{\θ}}{1+{\cos }^2\mathrm{\θ}}& \frac{2{\cos }^2\mathrm{\θ}}{1+{\cos }^2\mathrm{\θ}}\end{array}\right]\·\left[\begin{array}{c}{T}_{\mathrm{HOT}}\\ T_{\mathrm{COLD}}\end{array}\right]---\left(4\right)$

Can find out T from formula (4) _vAnd T _hChange with θ, promptly when the θ angle changed, the output brightness temperature in microwave radiometer alternating temperature source also changed, and chooses a plurality of θ, just can obtain a plurality of brightness temperature outputs, reached the purpose of alternating temperature source output.Alternating temperature source output brightness temperature is shown in formula (5)～(8) under some special angle.

Case hot source temperature T _HOTBe 300K, sink temperature T _COLDBe 80K, through the anglec of rotation, just can obtain any temperature between these two temperature so.Fig. 3 is linear polarization microwave radiometer alternating temperature source output brightness temperature and polarization grid anglec of rotation graph of a relation, can find out from figure and pass through rotary polarization grid angle so, just can obtain any temperature between low-temperature receiver and the heat source temperature, realizes the alternating temperature purpose.

$\left\{\begin{array}{c}{T}_v=\frac{6}{7}{T}_{\mathrm{HOT}}+\frac{1}{7}{T}_{\mathrm{COLD}}\\ T_h=\frac{1}{7}{T}_{\mathrm{HOT}}+\frac{6}{7}{T}_{\mathrm{COLD}}\end{array}\right.$ θ＝30° (5)

$\left\{\begin{array}{c}{T}_v=\frac{2}{3}{T}_{\mathrm{HOT}}+\frac{1}{3}{T}_{\mathrm{COLD}}\\ T_h=\frac{1}{3}{T}_{\mathrm{HOT}}+\frac{2}{3}{T}_{\mathrm{COLD}}\end{array}\right.$ θ＝45° (6)

$\left\{\begin{array}{c}{T}_v=\frac{2}{5}{T}_{\mathrm{HOT}}+\frac{3}{5}{T}_{\mathrm{COLD}}\\ T_h=\frac{3}{5}{T}_{\mathrm{HOT}}+\frac{2}{5}{T}_{\mathrm{COLD}}\end{array}\right.$ θ＝60° (7)

$\left\{\begin{array}{c}{T}_v=T_{\mathrm{COLD}}\\ T_h=T_{\mathrm{HOT}}\end{array}\right.$ θ＝90° (8)

It should be noted last that above embodiment is only unrestricted in order to technical scheme of the present invention to be described.Although the present invention is specified with reference to embodiment; Those of ordinary skill in the art is to be understood that; Technical scheme of the present invention is made amendment or is equal to replacement, do not break away from the spirit and the scope of technical scheme of the present invention, it all should be encompassed in the middle of the claim scope of the present invention.

Claims (7)

1. linear polarization microwave radiometer alternating temperature source apparatus, this alternating temperature source apparatus comprises: central point is positioned at low-temperature receiver, thermal source and the polarization grid on the same surface level;

Described low-temperature receiver is used to provide the output of low temperature brightness temperature;

Described thermal source is used to provide the output of high temperature brightness temperature;

Described polarization grid is used for exporting the bright temperature of linear polarization microwave radiation of variation through changing the polarization grid anglec of rotation;

Described low-temperature receiver and described thermal source are divided into the both sides of described polarization grid, and the center of the center of described polarization grid and microwave radiometer test antenna is all on the central axis of system; It is characterized in that,

Described polarization grid is the rotatable setting in center with the central shaft perpendicular to polarization grid place face.

2. linear polarization microwave radiometer alternating temperature source apparatus according to claim 1 is characterized in that, the temperature of described cold/heat source keeps fixed value.

3. linear polarization microwave radiometer alternating temperature source apparatus according to claim 1 is characterized in that the main body of described cold/heat source is a black matrix.

4. linear polarization microwave radiometer alternating temperature source apparatus according to claim 1 is characterized in that described polarization grid is rounded.

5. linear polarization microwave radiometer alternating temperature source apparatus according to claim 1; It is characterized in that; Described low-temperature receiver is placed perpendicular to the central axis of system; Described thermal source is parallel to the central axis of system to be placed, and described polarization grid is arranged on the angular bisector of 90 ° of angles of radiating surface of radiating surface and described thermal source of described low-temperature receiver.

6. linear polarization microwave radiometer alternating temperature source apparatus according to claim 5 is characterized in that, the brightness temperature T of described linear polarization microwave radiometer output _h, t _vWith the bright temperature T of thermal source _HOT, the bright temperature T of low-temperature receiver _COLDAnd the relational expression between the polarization grid anglec of rotation θ is:

$\left[\begin{array}{c}{T}_v\\ T_h\end{array}\right]=\left[\begin{array}{cc}\frac{2{\cos }^2\mathrm{\θ}}{1+{\cos }^2\mathrm{\θ}}& \frac{{\sin }^2\mathrm{\θ}}{1+{\cos }^2\mathrm{\θ}}\\ \frac{{\sin }^2\mathrm{\θ}}{1+{\cos }^2\mathrm{\θ}}& \frac{2{\cos }^2\mathrm{\θ}}{1+{\cos }^2\mathrm{\θ}}\end{array}\right]\·\left[\begin{array}{ccc}{r}_{\left|\right|}& t_{\left|\right|}& L_{\left|\right|}\\ r_{\⊥}& t_{\⊥}& L_{\⊥}\end{array}\right]\·\left[\begin{array}{c}{T}_{\mathrm{HOT}}\\ T_{\mathrm{COLD}}\\ T_G\end{array}\right]---\left(1\right)$

In the formula (1), T _GThe physical temperature of expression metal grill; r _||, t _||, and L _||The reflection coefficient of representing metal grill when the mesh lines direction is parallel with the polarization of ele direction respectively, transmission coefficient and ohmic loss; r _⊥, t _⊥, L _⊥Represent reflection coefficient, transmission coefficient and ohmic loss when vertical respectively.

7. linear polarization microwave radiometer alternating temperature source apparatus according to claim 6 is characterized in that, when described polarization grid is the perfect polarization grid, and the brightness temperature T of described linear polarization microwave radiometer output _hAnd T _vWith the bright temperature T of thermal source _HOT, the bright temperature T of low-temperature receiver _COLDAnd the relational expression between the polarization grid anglec of rotation θ is:

$\left[\begin{array}{c}{T}_v\\ T_h\end{array}\right]=\left[\begin{array}{cc}\frac{2{\cos }^2\mathrm{\θ}}{1+{\cos }^2\mathrm{\θ}}& \frac{{\sin }^2\mathrm{\θ}}{1+{\cos }^2\mathrm{\θ}}\\ \frac{{\sin }^2\mathrm{\θ}}{1+{\cos }^2\mathrm{\θ}}& \frac{2{\cos }^2\mathrm{\θ}}{1+{\cos }^2\mathrm{\θ}}\end{array}\right]\·\left[\begin{array}{c}{T}_{\mathrm{HOT}}\\ T_{\mathrm{COLD}}\end{array}\right]---\left(2\right).$

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