Radiometer for microwave receiver and method for measuring temperature of detector

Abstract

A radiometer for a microwave receiver according to an embodiment of the present invention includes an antenna line receiving radiated power corresponding to a temperature of a detector from an antenna, a first reference rod having a first reference temperature fixed in advance, a second reference rod having a second reference temperature fixed in advance, a first microwave switch selectively switching the antenna line, the first reference rod, and the second reference rod, a second microwave switch switched with the same clock as the first microwave switch, a demodulator multiplying a signal output from the second microwave switch by a predetermined gain value and outputting the result, an integrator integrating the signal output from the demodulator, and a controller measuring the temperature of the detector based on the signal output from the integrator.

Description

[Technical field]

[0001] The present invention relates to a radiometer for a microwave receiver and a method for measuring the temperature of a detector using the radiometer, and more particularly to a radiometer for a microwave receiver and a method for measuring the temperature of a detector using the radiometer, which can easily and accurately measure the temperature of a detector without the need to vary the reference temperature of a reference rod. [Background technology]

[0002] According to Plank's blackbody radiation principle, the wavelength and amount of components of light and radio waves radiated by a material can be expressed as a function of temperature. In the microwave frequency range (300MHz~300GHz), the radiated signal is given by the following [Equation 1] according to the Rayleigh-Jeans law, and has a value proportional to the square of the frequency f and the temperature T. Therefore, the radiated power Pn within the frequency bandwidth BW received by the antenna is given by the following [Equation 2]. If the radiated power received through a microwave receiver, i.e., the noise power, is amplified and finally measured using [Equation 2], it becomes possible to measure the temperature proportional to this, which is called a radiometer.

[0003]

number

[0004] (k: Boltzmann constant, c: speed of light in a vacuum, T: absolute temperature, f: frequency)

[0005]

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[0006] There are two types of radiometers: total power radiometers, which simply amplify the received radiated power (noise) and measure the output, and Dicke radiometers, which have excellent temperature resolution.

[0007] FIG. 1 is a diagram for explaining a conventional Dicke radiometer and the principle of its receiving operation.

[0008] Referring to FIG. 1, in the conventional Dicke radiometer, microwave switches 2a and 2b and a demodulator 6 are switched by the same clock. The temperature of the object to be detected is detected by the antenna 1 as "T A The first microwave switch 2a receives the radiated power corresponding to T A For comparison, the reference rod (ref.Load) 3 "T ref The reference power corresponding to " is received by the receiver 4 according to the switching of the first microwave switch 2a. A Radiated power or T ref The receiver 4 processes the input power signal and outputs it to the detector 5, and the output of the detector 5 is input to the second microwave switch 2b.

[0009] When the first microwave switch 2a is connected to the antenna 1, the second microwave switch 2b connects the detector 5 to the first amplifier P1 of the demodulator 6, while when the first microwave switch 2a is connected to the reference rod 3, the second microwave switch 2b connects the detector 5 to the second amplifier P2 of the demodulator 6. Here, the first amplifier P1 and the second amplifier P2 have the same gain and opposite polarities (+A, -A).d " is the detector constant of detector 5.

[0010] The demodulator 6 combines the outputs of the first amplifier P1 and the second amplifier P2 and outputs them to the integrator 7, and the output voltage V out is input to a controller 8.

[0011] The integrator 7 has T for half a period t1. A The radiated power corresponding to and for the remaining half period t2 is T ref The reference power corresponding to is input as a negative number. After passing through the integrator 7, the output voltage V out is "kBG RX C d At0(T A -T ref )" where T A =T ref If the output voltage V out becomes "0". Unlike a total power radiometer, such a conventional Dicke radiometer has an output voltage (T A -T ref ) so that T of receiver 4 RX is unaffected, and the gain of receiver 4, G RX It is also insensitive to changes in T ref T A can also be sought.

[0012] However, the conventional Dicke radiometer only measures the temperature of the object to be measured, i.e., the radiated power entering through the antenna 1, called "T A For the measurement of "T ref However, such control is complicated and difficult to implement. Specifically, the conventional Dicke radiometer controls the resistance or equivalent temperature T ref Vary T A This is the output voltage V of the integrator 7. outThis is the moment when T becomes "0". ref It is difficult to find exactly the T ref It is not easy to make such a radiometer. Therefore, a radiometer that can measure the temperature of a detector more easily and accurately is needed. Summary of the Invention [Problem to be solved by the invention]

[0013] The present invention provides a radiometer for a microwave receiver and a method for measuring the temperature of a detector, which can easily and accurately measure the temperature of a detector to be measured. [Means for solving the problem]

[0014] A radiometer for a microwave receiver according to an embodiment of the present invention includes an antenna line receiving radiated power corresponding to a temperature of a detector from an antenna, a first reference rod having a first reference temperature fixed in advance, a second reference rod having a second reference temperature fixed in advance, a first microwave switch selectively switching the antenna line, the first reference rod, and the second reference rod, a second microwave switch switched with the same clock as the first microwave switch, a demodulator multiplying a signal output from the second microwave switch by a predetermined gain value and outputting the result, an integrator integrating the signal output from the demodulator, and a controller measuring the temperature of the detector based on the signal output from the integrator.

[0015] In addition, a method for measuring the temperature of a detector in a radiometer for a microwave receiver according to another embodiment of the present invention includes, in the radiometer according to the embodiment, a first switching step in which the first microwave switch is alternately switched between the antenna line and the first reference rod according to the clock, a second switching step in which the first microwave switch is alternately switched between the antenna line and the second reference rod according to the clock, and a measurement step in which the temperature of the detector is measured based on a first output voltage output from the integrator by the first switching step and a second output voltage output from the integrator by the second switching step. Effect of the Invention

[0016] The microwave receiver radiometer according to the embodiment of the present invention has an advantage that the temperature of a detection object can be measured easily and accurately.

[0017] In particular, compared to conventional Dicke radiometers, there is an advantage that there is no need to variably control the reference temperature of the reference rod, and the temperature of the detector can be measured easily and simply by using two reference temperatures fixed at specific values. [Brief description of the drawings]

[0018] FIG. 1 is a diagram for explaining a conventional Dicke radiometer and the principle of its receiving operation.

[0019] FIG. 2 is a radiometer for a microwave receiver according to an embodiment of the present invention.

[0020] FIG. 3 is a graph showing a temperature T of a detector of the microwave receiver radiometer according to the embodiment of the present invention shown in FIG. A 1 is a flow chart of a method for measuring

[0021] FIG. 4 is a graph showing a state where the microwave receiver radiometer according to the embodiment of the present invention shown in FIG. 2 detects the temperature T A 1 is a graph for explaining a method for measuring DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Hereinafter, the embodiments disclosed herein will be described in detail with reference to the attached drawings, and the same or similar components will be given the same reference numerals regardless of the drawing numbers, and the repeated description thereof will be omitted. In describing the embodiments disclosed herein, if it is determined that a detailed description of the related publicly disclosed technology may obscure the gist of the embodiments disclosed herein, the detailed description will be omitted. In addition, the attached drawings are merely for making the embodiments disclosed herein easier to understand, and the technical ideas disclosed herein are not limited by the attached drawings, and should be understood to include all modifications, equivalents, or alternatives included in the ideas and technical scope of the present invention.

[0023] FIG. 2 is a radiometer for a microwave receiver according to an embodiment of the present invention.

[0024] Referring to FIG. 2, a radiometer for a microwave receiver according to an embodiment of the present invention has two reference rods 130a, 130b, in comparison with the conventional Dicke radiometer shown in FIG. 1, and a first microwave switch 120a selectively electrically connects one of the antenna 110, the first reference rod 130a, and the second reference rod 130b to the receiver 140 according to switching.

[0025] More specifically, a radiometer according to an embodiment of the present invention includes an antenna 110, microwave switches 120a, 120b, first and second reference loads 130a, 130b, a receiver 140, a detector 150, a demodulator 160, an integrator 170, and a controller 180.

[0026] The microwave switches 120a and 120b include a first microwave switch 120a and a second microwave switch 120b. The first microwave switch 120a and the second microwave switch 120b are switched by the same clock.

[0027] The first microwave switch 120a is electrically connected to the antenna line and to the first and second reference rods 130a and 130b, respectively. It is also electrically connected to the receiver 140. Here, the antenna line means a path electrically connected to the antenna 110. Components other than the antenna 110 may be located on the line.

[0028] The first microwave switch 120a may include a first terminal electrically connected to the antenna line, a second terminal electrically connected to the first reference rod 130a, a third terminal electrically connected to the second reference rod 130b, and a fourth terminal electrically connected to the receiver 140.

[0029] The first microwave switch 120a electrically connects one of the antenna 110, the first reference rod 130a, and the second reference rod 130b to the receiver 140 according to switching. When the first microwave switch 120a electrically connects the antenna line to the receiver 140, the temperature T Ais input to the receiver 140 through the antenna line. Meanwhile, when the first microwave switch 120a electrically connects the first reference rod 130a to the receiver 140, the first reference temperature T ref1 When the first reference power corresponding to is input to the receiver 140 and the first microwave switch 120a electrically connects the second reference rod 130b to the receiver 140, the second reference temperature T ref2 A second reference power corresponding to is input to the receiver 140.

[0030] The receiver 140 has a bandwidth B and a total power gain G RX The receiver may be a superheterodyne receiver having

[0031] The receiver 140 processes the signal input from the first microwave switch 120a. For example, the receiver 140 receives the power signal input by switching of the first microwave switch 120a, the temperature T A , the first reference temperature T ref1 and a second reference temperature T from the second reference rod 130b. ref2 In this case, it is possible to predetect any one of the power signals of the second reference powers corresponding to the first reference powers.

[0032] The detector 150 may be a square-law detector that outputs a signal proportional to the square of the amplitude of the signal input from the receiver 140, and may be configured with a semiconductor diode.

[0033] The second microwave switch 120b is coupled between the detector 150 and the demodulator 160. The second microwave switch 120b electrically couples the detector 150 to the first amplifier P1 or the second amplifier P2 according to switching. The second microwave switch 120b has a first output terminal coupled to the first amplifier P1 and a second output terminal coupled to the second amplifier P2.

[0034] The demodulator 160 includes a first amplifier P1, a second amplifier P2, and a summer S. The first amplifier P1 and the second amplifier P2 have the same gain but opposite polarities (+A, -A) and are electrically connected to the second microwave switch 120b. The outputs of the first amplifier P1 and the second amplifier P2 are added by the summer S and output.

[0035] The integrator 170 accumulates the signal input from the demodulator 160 for a predetermined time and transmits a predetermined output voltage to the controller 180 .

[0036] The controller 180 calculates the temperature T of the detector based on the output voltage from the integrator 170. A The temperature of the detector T A Specific methods for measuring are described in detail below.

[0037] In the following, the microwave receiver radiometer according to the embodiment of the present invention shown in FIG. A A method for measuring the above will be described with reference to FIG.

[0038] FIG. 3 is a graph showing a temperature T of a detector of the microwave receiver radiometer according to the embodiment of the present invention shown in FIG. A 1 is a flow chart of a method for measuring

[0039] The temperature T of the detector of the microwave receiver radiometer according to the embodiment of the present invention A The measurement method is based on a first reference temperature Tref1 and the second reference temperature T ref2 is used.

[0040] Referring to FIG. 3, the temperature T of the detector of the microwave receiver radiometer according to the embodiment of the present invention is A The measurement method is to measure the first output voltage V between the antenna line and the first reference rod 130a. out1 and measuring a second output voltage V between the antenna line and the second reference rod 130b. out2 and determining the temperature T of the detector based on the measured first and second output voltages. A and measuring 330 .

[0041] A first output voltage V between the antenna line and the first reference rod 130a out1 The step 310 of measuring the first output voltage V of the integrator 170 will be described. If the first and second microwave switches 120a and 120b are switched by the same clock, and the first microwave switch 120a alternately switches between the antenna 110 and the first reference rod 130a while the second microwave switch 120b alternately switches between the first amplifier P1 and the second amplifier P2 of the demodulator 160, out1 is expressed by the following [Equation 3].

[0042]

number

[0043] where k is the Boltzmann constant, B is the receiver bandwidth, and G RX is the receiver gain, C d is the detector constant, A is the gain of the first and second amplifiers, and t0 is the time in half a clock period.

[0044] Next, a second output voltage V between the antenna line and the second reference rod 130b is out2The step 320 of measuring the second output voltage V of the integrator 170 will be described. If the first and second microwave switches 120a and 120b are switched by the same clock, and the first microwave switch 120a alternately switches between the antenna 110 and the second reference rod 130b while the second microwave switch 120b alternately switches between the first amplifier P1 and the second amplifier P2 of the demodulator 160, out2 is expressed by the following [Equation 4].

[0045]

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[0046] Finally, the measured first and second output voltages V out1 ,V out2 Based on the temperature of the detector T A The step 330 of measuring the first output voltage V out1 and the second output voltage V in [Equation 4] above out2 The ratio is as shown in [Equation 5] below.

[0047]

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[0048] The temperature T of the detector to be measured in the above [Equation 5] A When this is rearranged, it becomes as shown in [Equation 6] below.

[0049]

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[0050] The temperature of the detector T is calculated by the above [Equation 6]. A In calculating the temperature of the detector, α is unnecessary and can be removed. A are two reference temperatures T ref1 ,T ref2The first and second output voltages V out1 ,V out2 can be easily and accurately measured.

[0051] FIG. 4 is a graph showing a state where the microwave receiver radiometer according to the embodiment of the present invention shown in FIG. 2 detects a temperature T A 1 is a graphical illustration of a method for measuring

[0052] As shown in the graph in Figure 4, V out Only by knowing the slope α of the linear function A However, the measurement of one reference temperature is T A Therefore, by using the radiometer according to the embodiment of the present invention shown in FIG. ref1 ,T ref2 and two reference temperatures T ref1 ,T ref2 The output voltage V out1 ,V out2 The temperature of the detector T A The radiometer according to the embodiment of the present invention can accurately measure the temperature T A There is no need to control and vary the reference temperature of the reference rod to measure the gain G of the radiometer, and the characteristics of the internal configuration of the radiometer, i.e., the bandwidth B and gain G of the receiver 140, are measured. RX , detector constant C of detector 150 d , the temperature T of the detector is detected regardless of the gain and polarity of the first and second amplifiers P1, P2. A can be easily and accurately measured.

[0053] Meanwhile, the above-described method for measuring the temperature of a detector in a radiometer for a microwave receiver may be embodied in the form of program instructions that can be executed by various computer means and recorded on a computer-readable medium. The computer-readable recording medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions recorded on the medium may be specially designed and constructed for the present invention, or may be publicly available to those skilled in the art of computer software. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tapes, optical media such as CD-ROMs and DVDs, magneto-optical media such as floptical disks, and hardware devices specially configured to store and execute program instructions, such as ROMs, RAMs, flash memories, and the like. Examples of program instructions include not only machine language codes such as those created by a compiler, but also high-level language codes that can be executed by a computer using an interpreter, etc. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

[0054] The features, structures, effects, etc. described in the above embodiments are included in one embodiment of the present invention and are not necessarily limited to one embodiment. Furthermore, the features, structures, effects, etc. exemplified in each embodiment can be combined or modified in other embodiments by a person having ordinary knowledge in the field to which the embodiment belongs. Therefore, the contents related to such combinations and modifications should be interpreted as being included in the scope of the present invention. [Explanation of symbols]

[0055] 110 Antenna 120a 1st microwave switch 120b Second microwave switch 130a 1st Reference Rod 130b 2nd Reference Rod 140 Receiver 150 Detector 160 Demodulator 170 Integrator 180 Controller

Claims

1. an antenna line for receiving radiated power corresponding to the temperature of a detection object from an antenna; a first reference rod having a first pre-fixed reference temperature; a second reference rod having a second pre-fixed reference temperature; a first microwave switch that selectively switches the antenna line, the first reference rod, and the second reference rod; a second microwave switch that is switched by the same clock as the first microwave switch; a demodulator that multiplies the signal output from the second microwave switch by a predetermined gain value and outputs the result; an integrator that integrates a signal output from the demodulator; a controller for measuring the temperature of the detector based on the signal output from the integrator; Including, The signal output from the integrator includes a first output voltage based on the first microwave switch alternately switching between the antenna line and the first reference rod, and a second output voltage based on the first microwave switch alternately switching between the antenna line and the second reference rod, a temperature of the detector is determined based on the first and second reference temperatures and the first and second output voltages; The temperature of the detector is determined by the following formula: [Formula] Here, T A is the temperature of the detector, T ref1 is the first reference temperature, T ref2 is the second reference temperature, and V out1 is the first output voltage, and V out2 is the second output voltage.

2. a receiver and a detector located between the first microwave switch and the second microwave switch; the demodulator includes a first amplifier connected to a first output terminal of the second microwave switch, a second amplifier connected to a second output terminal of the second microwave switch, and a summer that adds output signals of the first amplifier and the second amplifier, 2. The radiometer for a microwave receiver according to claim 1, wherein said first amplifier and said second amplifier have the same gain and opposite polarity.

3. The method for measuring temperature of a detector in a radiometer according to claim 1, a first switching stage in which the first microwave switch is alternately switched between the antenna line and the first reference rod according to the clock; a second switching stage in which the first microwave switch is alternately switched between the antenna line and the second reference rod according to the clock; a measuring step of measuring a temperature of the detector based on a first output voltage output from the integrator by the first switching step and a second output voltage output from the integrator by the second switching step; Including, The temperature of the detector is determined by the following formula: [Formula] Here, T A is the temperature of the detector, T ref1 is the first reference temperature, T ref2 is the second reference temperature, and V out1 is the first output voltage, and V out2 is the second output voltage.

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