High-stability waveguide thermocouple power sensor and method

Abstract

The invention belongs to the technical field of measuring instruments, and relates to a high-stability waveguide thermocouple power sensor and a method. Comprising two branches, wherein the first branch is composed of a microstrip line, a first gradual change structure, a first coplanar waveguide and a first thermocouple chip; the second branch is composed of a microstrip line, a filter, a second gradual change structure, a second coplanar waveguide and a second thermocouple chip; a to-be-measured input signal is transited through the waveguide probe to complete conversion from the waveguide transmission line to the microstrip line, then thermoelectric conversion is completed through the first branch, a direct current signal is generated, and the size of the direct current signal is in direct proportion to the power of a to-be-measured radio frequency signal; and a thermocouple signal reflecting the environment temperature change is generated through the second branch. The invention is more suitable for measuring the signal power of the waveguide device, and avoids the increase of transmission loss and impedance mismatch of the port caused by the introduction of the adapter. According to the sensor, the heat balance time is shortened, meanwhile, the influence of external temperature conversion on the device is reduced, noise drift is reduced, and the stability and environmental adaptability of the device are improved.

Description

Technical Field

[0001] This invention belongs to the field of measuring instrument technology and relates to a high-stability waveguide thermocouple power sensor and method. Background Technology

[0002] Thermocouple power meters are important measuring instruments used for power measurement. Their basic working principle involves converting the signal to be measured into heat through a thin-film resistor, utilizing the Seebeck effect of the thermocouple material to achieve thermoelectric conversion, and then using external detection circuitry to measure the power. This type of power meter features a wide operating frequency range, low VSWR, high linearity, and high measurement accuracy.

[0003] Existing thermocouple power sensors mostly employ coaxial transmission lines, primarily consisting of four parts: a coaxial connector, a planar transmission line, a load terminal, and a thermopile. The microwave signal is transmitted to the load terminal via the coaxial connector and planar transmission line, where the microwave power is converted into heat. The Seebeck effect then causes the thermopile, placed near the load terminal, to convert the heat into DC voltage. Testing waveguide port devices typically requires adapters, and existing thermocouple power sensor designs are susceptible to changes in ambient temperature, requiring prolonged preheating during low-power signal testing and exhibiting susceptibility to noise drift. Summary of the Invention

[0004] To address the problem that existing waveguide thermocouple power sensors are susceptible to the influence of ambient temperature, this invention proposes a highly stable waveguide thermocouple power sensor. Through a dual-path design, the influence of ambient temperature is offset, thereby enhancing the stability and environmental adaptability of the power sensor.

[0005] The technical solution provided by this invention is: a high-stability waveguide thermocouple power sensor, comprising two branches. The first branch consists of a microstrip line, a first gradient structure, a first coplanar waveguide, and a first thermocouple chip; the second branch consists of a microstrip line, a low-pass filter, a second gradient structure, a second coplanar waveguide, and a second thermocouple chip. The input signal to be measured is converted from a waveguide transmission line to a microstrip line via a waveguide probe, and then thermoelectrically converted via the first branch to generate a DC signal. The magnitude of this DC signal is proportional to the power of the radio frequency signal to be measured. A thermocouple DC signal reflecting changes in ambient temperature is generated via the second branch.

[0006] Preferably, the stopband range of the low-pass filter is not less than the operating frequency range of the waveguide thermocouple sensor.

[0007] Furthermore, the present invention also provides a high-stability waveguide thermocouple power measurement method. This method utilizes the sensor provided by the present invention. The input signal to be measured is converted from a waveguide transmission line to a microstrip line via a waveguide probe. Then, the power of the signal to be measured is measured through the first branch, and the thermocouple signal caused by the change in ambient temperature is measured through the second branch. The measured value of the first branch is subtracted from the measured value of the second branch, and the power of the signal to be measured is obtained through data processing of the detection circuit.

[0008] The high-stability waveguide thermocouple power sensor and method provided by this invention are more suitable for waveguide device signal power measurement, avoiding the increase in transmission loss and impedance mismatch at the port caused by the introduction of the adapter; secondly, the sensor of this invention will shorten the thermal equilibrium time, reduce the impact of external temperature changes on the device, reduce noise drift, and improve the stability and environmental adaptability of the device. Attached Figure Description

[0009] Figure 1 This is a structural block diagram of the high-stability waveguide thermocouple power sensor provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of the high-stability waveguide thermocouple power sensor provided in an embodiment of the present invention. Detailed Implementation

[0010] To more clearly understand the technical content of this invention, its solution will now be described in detail with reference to the accompanying drawings and specific embodiments. The accompanying drawings show a preferred embodiment of this invention, but its scope of protection is not limited thereto, and can be flexibly adjusted according to specific usage requirements in practical applications. This embodiment aims to help those skilled in the art to fully and deeply understand the inventive concept of this solution.

[0011] This invention proposes a highly stable waveguide thermocouple power sensor, which uses a dual-path design to offset the effects of ambient temperature, thereby enhancing the stability and environmental adaptability of the power sensor. Figure 1 and 2 As shown, the sensor includes two branches. The first branch 10 consists of a microstrip line 50, a first gradient structure 11, a first coplanar waveguide 12, and a first thermocouple chip 13. The second branch 20 consists of a microstrip line 50, a filter 21, a second gradient structure 22, a second coplanar waveguide 23, and a second thermocouple chip 24.

[0012] The input signal under test is converted from a waveguide transmission line to a microstrip line 50 via a standard waveguide 30 and a probe transition 40. Then, it is converted into a first coplanar waveguide 12 via a first gradient structure 11. Finally, the signal is transmitted to the first thermocouple chip 13, where Joule heat is generated. The thermoelectric conversion is completed using the Seebeck effect of the thermocouple material to generate a DC signal. The magnitude of the DC signal is proportional to the power of the radio frequency signal under test, that is, normal power measurement is achieved in the first branch 10.

[0013] In the second branch 20, the input signal under test is also converted from a waveguide transmission line to a microstrip line via a waveguide probe, then transformed into a second coplanar waveguide 23 via a filter 21 and a second tapered structure 22, and finally connected to the second thermocouple chip 24. In this branch, the stopband range of the filter 21 is designed to be the operating range of the waveguide thermocouple power sensor, or a low-pass filter scheme is used, designing the operating frequency range of the waveguide thermocouple sensor to be within the stopband range of the low-pass filter. At this time, due to the presence of the filter 21, the RF signal under test will only be transmitted along the first branch 10, and will be cut off in the second branch 20. Since there is no signal transmission in the second branch 20, the voltage change generated in the second thermocouple chip 24 reflects the voltage change caused by the change in external temperature. The voltage change generated by the first thermocouple chip 13 in the first branch 10 is subtracted from the voltage change generated by the second thermocouple chip 24 in the second branch 20. Furthermore, the measured value of the first branch is subtracted from the measured value of the second branch. Through data processing of the detection circuit, the voltage change caused by the RF signal input can be obtained, thereby reducing the influence of ambient temperature and the temperature imbalance problem introduced by the device under test.

[0014] The high-stability waveguide thermocouple power sensor proposed in this invention achieves a transition from the standard waveguide port to the thermocouple chip coplanar waveguide through a waveguide-probe-microstrip-gradient structure-coplanar waveguide-thermocouple chip transition design, thus meeting the testing requirements of waveguide devices. The first branch is used for normal signal power testing, and the second branch is used for thermocouple signal change testing under external temperature variations. Through data processing of the detection circuit, the influence of external temperature changes on the entire sensor is reduced, thereby improving stability and environmental adaptability.

Claims

1. A high-stability waveguide thermocouple power sensor, characterized in that: It includes two branches. The first branch consists of a microstrip line, a first tapered structure, a first coplanar waveguide, and a first thermocouple chip. The second branch consists of a microstrip line, a filter, a second tapered structure, a second coplanar waveguide, and a second thermocouple chip. The input signal under test is converted from a waveguide transmission line to a microstrip line via a waveguide probe, and then thermoelectrically converted via the first branch to generate a DC signal. The magnitude of the DC signal is proportional to the power of the RF signal under test. The second branch generates a thermocouple signal that reflects changes in ambient temperature.

2. The high-stability waveguide thermocouple power sensor according to claim 1, characterized in that: The operating frequency range of the waveguide thermocouple power sensor is within the stopband range of the filter.

3. A method for testing the power of a high-stability waveguide thermocouple, characterized in that: This method utilizes the sensor described in claim 1 or 2. The input signal to be measured is converted from a waveguide transmission line to a microstrip line via a waveguide probe. Then, the power of the signal to be measured is measured through the first branch, and the thermocouple signal caused by the change in ambient temperature is measured through the second branch. The measured value of the first branch is subtracted from the measured value of the second branch, and the power of the signal to be measured is obtained through data processing of the detection circuit.

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