CN110133367B - Load for millimeter wave calorimetric microwave power meter - Google Patents
Load for millimeter wave calorimetric microwave power meter Download PDFInfo
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- CN110133367B CN110133367B CN201910516309.9A CN201910516309A CN110133367B CN 110133367 B CN110133367 B CN 110133367B CN 201910516309 A CN201910516309 A CN 201910516309A CN 110133367 B CN110133367 B CN 110133367B
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- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R21/00—Arrangements for measuring electric power or power factor
- G01R21/02—Arrangements for measuring electric power or power factor by thermal methods, e.g. calorimetric
Abstract
The invention discloses a load for a millimeter wave calorimetric microwave power meter, which comprises: the microwave dry load, the liquid circulation and heat conduction channel, the liquid channel inlet, the liquid channel outlet, the waveguide mode converter, the heat insulation device and the sealed shell; the sealed shell is fixed in the inner cavity of the heat insulation device, the microwave dry load is arranged in the cavity of the sealed shell, the input end of the waveguide mode converter extends out of the heat insulation device, the output end of the waveguide mode converter is connected with the microwave inlet of the microwave dry load, and the waveguide mode converter is used for converting the microwave inlet of the microwave dry load into a waveguide interface with standard specification; a liquid circulation and heat conduction channel is arranged between the microwave dry load and the inner wall of the sealed shell, and a liquid channel inlet and a liquid channel outlet are arranged between the heat insulation device and the sealed shell; the load can overcome the problems that the direct measurement and high-power water load method in the prior art can not measure the millimeter wave power from a few watts to a few hundred watts, and the precision of a coupling measurement method is not enough.
Description
Technical Field
The invention relates to the field of microwave power measurement of millimeter wave frequency bands, in particular to a load for a millimeter wave calorimetric microwave power meter.
Background
Among the key radio metering parameters specified by the international metering agency, power is the most basic quantity, and millimeter wave power measurement plays an important role in civil communication and military and defense fields. Typically, low power millimeter waves (in the order of milliwatts) can be measured directly and accurately by existing commercial equipment. When measuring medium and low power millimeter waves (several watts to hundreds of watts), a small power microwave with equal proportion can be obtained through the directional coupler, then the small power microwave is directly measured, and then microwave power is obtained according to the coupling coefficient of used devices, but the coupling coefficient coefficients of the devices under different frequencies and different powers can be changed, so that the measurement accuracy is not high. The calorimetric water load can also be used for millimeter wave power measurement, water flowing at a certain speed of the load is used as a microwave absorbing medium, microwave energy is lost in the water and converted into heat energy of the water, and the microwave power can be calculated through a formula by measuring the temperature difference of an inlet and an outlet of the water load. However, the existing measurement method is used for high-power millimeter wave measurement, the power is generally above kilowatt level, and otherwise the precision cannot be guaranteed.
Disclosure of Invention
The invention provides a load for a millimeter wave calorimetric microwave power meter, and aims to solve the problems that the millimeter wave power of several watts to several hundred watts cannot be measured by a direct measurement method and a high-power water load method, and the precision of a coupling measurement method is not enough.
In order to achieve the above object, the present application provides a load for a millimeter wave calorimetric microwave power meter, the load comprising:
the microwave dry load, the liquid circulation and heat conduction channel, the liquid channel inlet, the liquid channel outlet, the waveguide mode converter, the heat insulation device and the sealed shell;
the heat insulation device and the sealing shell are both cavity bodies, the sealing shell is fixed in an inner cavity of the heat insulation device, the microwave dry load is installed in a cavity of the sealing shell, the input end of the waveguide mode converter extends out of the heat insulation device, the output end of the waveguide mode converter is connected with a microwave inlet of the microwave dry load, and the waveguide mode converter is used for converting the microwave inlet of the microwave dry load into a waveguide interface with a standard specification; a liquid circulation and heat conduction channel is arranged between the microwave dry load and the inner wall of the sealed shell, and a liquid channel inlet and a liquid channel outlet are arranged between the heat insulation device and the sealed shell.
The microwave dry load consists of a cavity and a solid wave-absorbing material and has the characteristic of low standing-wave ratio in a working frequency band, namely only a tiny part of microwave energy is reflected back to ensure that the microwave energy is absorbed by the wave-absorbing material and converted into heat energy; the solid wave-absorbing material can be silicon carbide, carbon powder and other materials with excellent millimeter wave absorption characteristics.
The waveguide mode converter converts a microwave inlet of the microwave dry load into a waveguide interface with a standard specification, so that the microwave dry load can be connected with a waveguide with the standard specification in a matching manner, and the lowest reflection and loss of microwave energy in the transmission process are ensured.
The liquid circulation and the heat conduction channel are tightly attached to the part of the wave-absorbing material which generates heat, so that the liquid medium can uniformly flow in the channel and absorb heat energy, and the system can form stable temperature difference at the inlet and the outlet of the liquid channel when in normal operation, wherein the liquid medium can be water, alcohol, kerosene, ether and the like.
The liquid channel interface is composed of a liquid inlet and a liquid outlet, wherein the liquid inlet is far away from the part of the microwave dry load generating heat as far as possible, and the heat energy is prevented from being conducted to the liquid inlet through the liquid or the wall of the liquid channel. And the liquid outlet is far away from the microwave dry load interface part as far as possible, so that the heat energy is prevented from being conducted to the outside through the microwave dry load interface.
The heat insulation device is of a cavity structure and is made of heat insulation materials or metal vacuum technology, the microwave dry load, the liquid circulation and the heat conduction channel are wrapped in the heat insulation device, a liquid channel interface is reserved, the microwave dry load interface can be connected with the outside, and heat energy generated by the microwave dry load is guaranteed not to exchange heat with the outside as much as possible.
Wherein, millimeter wave calorimetric microwave power meter includes:
the load module, the circulating constant temperature module, the 2 temperature measuring modules, the data acquisition and post-processing module, the flowmeter module and the controller module are arranged in the pipeline;
the load is of a cavity structure, the cavity structure absorbs and converts electromagnetic field energy of millimeter waves generated by the millimeter wave power source to be tested into heat and transfers the heat to the cavity wall, and a liquid medium channel is arranged on the cavity wall;
the circulating constant temperature module is used for generating liquid circulation, continuously taking away heat generated by the load and controlling the temperature of the liquid at the inlet of the load to be constant;
the 2 temperature measuring modules are respectively used for measuring the temperature of liquid flowing into the load inlet and the temperature of liquid flowing out of the load outlet;
a flow meter and controller module for controlling and measuring the flow of the liquid;
and the data acquisition and post-processing module is used for acquiring the temperature data measured by the 2 temperature measurement modules and the flow data measured by the flowmeter and the controller module into a computer or an embedded system, and obtaining the microwave power value through calculation.
One or more technical solutions provided by the present application have at least the following effects or advantages:
1. the invention overcomes the problems that the direct measurement and the high-power water load can not measure the millimeter wave power of several watts to several hundred watts, and the precision of the coupling measurement method is not enough.
2. The invention has the advantages of large measurable millimeter wave frequency bandwidth and large usable range.
3. The invention can adjust the flow speed of the liquid medium in the load according to the measured millimeter wave power so as to widen the power measurement range and achieve the optimal measurement precision.
4. The outermost layer of the invention is designed to be insulated, thus further improving the measurement precision.
Drawings
The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this application, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention;
fig. 1 is a schematic structural view of a load for a millimeter wave calorimetric microwave power meter;
FIG. 2 is a schematic diagram of the structure of a microwave dry load;
FIG. 3 is a schematic view of the structure of the inside of the heat insulating means;
fig. 4 is a schematic structural diagram of a millimeter wave calorimetric microwave power meter.
Detailed Description
In order that the above objects, features and advantages of the present invention can be more clearly understood, a more particular description of the invention will be rendered by reference to the appended drawings. It should be noted that the embodiments and features of the embodiments of the present application may be combined with each other without conflicting with each other.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, however, the present invention may be practiced in other ways than those specifically described and thus the scope of the present invention is not limited by the specific embodiments disclosed below.
The system structure of the invention is shown in fig. 1, and the load comprises:
the microwave dry load is 5, the liquid circulation and heat conduction channel 4, the liquid channel inlet 3, the liquid channel outlet 6, the waveguide mode converter 2, the heat insulation device 1 and the sealed shell 7;
the heat insulation device and the sealing shell are both cavity bodies, the sealing shell is fixed in an inner cavity of the heat insulation device, the microwave dry load is installed in a cavity of the sealing shell, the input end of the waveguide mode converter extends out of the heat insulation device, the output end of the waveguide mode converter is connected with a microwave inlet of the microwave dry load, and the waveguide mode converter is used for converting the microwave inlet of the microwave dry load into a waveguide interface with a standard specification; a liquid circulation and heat conduction channel is arranged between the microwave dry load and the inner wall of the sealed shell, and a liquid channel inlet and a liquid channel outlet are arranged between the heat insulation device and the sealed shell. The liquid medium used is water.
A specific microwave dry load configuration is shown in fig. 2. Comprises a microwave inlet 8, a cylindrical oxygen-free copper metal cavity 9 and wave-absorbing material carbon powder 10. The wave-absorbing material carbon powder is processed into a solid integral structure, and fills the cylindrical metal cavity and leaves an inverted cone-shaped cavity. The size of the metal cavity is 32mm in diameter and 165mm in length, and the microwave inlet is connected with the mode converter by adopting a flange. After being connected with a mode converter with the diameter of 32mm for transforming a standard rectangular waveguide WR28, the standing wave ratio of an input signal is less than 1.15 at 30-38 GHz.
The specific liquid circulation and heat conduction channel, the liquid channel interface and the microwave dry load cavity form an oxygen-free copper metal structure through machining and welding, and the structure is shown in figure 3. Comprises a microwave dry load cavity 11, a liquid channel outlet 13, a liquid channel inlet 14 and a liquid circulation and heat conduction channel 15. The spiral flow guide channel enables the liquid medium to flow around the microwave dry load and takes away heat energy generated by the microwave dry load.
The heat insulation device is of a cuboid cavity structure, the size of the heat insulation device is 40cm x 15cm, the heat insulation device is made of a glass fiber board with a heat insulation effect, a microwave dry load, a liquid circulation channel and a heat conduction channel are fixed in the heat insulation device, a liquid channel interface and a microwave mode converter interface are reserved and can be connected with the outside, meanwhile, the sealing cavity reduces internal gas heat convection, and the heat insulation effect of the heat insulation device is guaranteed.
The liquid channel interfaces are NPT-1/8 threaded interfaces, the liquid channel inlet is close to the microwave dry load interface, the liquid channel outlet is at the tail end of the microwave dry load, and when the system works, the liquid channel inlet and the liquid channel outlet form a stable temperature difference.
Referring to fig. 4, the millimeter wave calorimetric microwave power meter includes:
the load module, the circulating constant temperature module, the 2 temperature measuring modules, the data acquisition and post-processing module, the flowmeter module and the controller module are arranged in the pipeline;
the load is of a cavity structure, the cavity structure absorbs and converts electromagnetic field energy of millimeter waves generated by the millimeter wave power source to be tested into heat and transfers the heat to the cavity wall, and a liquid medium channel is arranged on the cavity wall;
the circulating constant temperature module is used for generating liquid circulation, continuously taking away heat generated by the load and controlling the temperature of the liquid at the inlet of the load to be constant;
the 2 temperature measuring modules are respectively used for measuring the temperature of liquid flowing into the load inlet and the temperature of liquid flowing out of the load outlet;
a flow meter and controller module for controlling and measuring the flow of the liquid;
and the data acquisition and post-processing module is used for acquiring the temperature data measured by the 2 temperature measurement modules and the flow data measured by the flowmeter and the controller module into a computer or an embedded system, and obtaining the microwave power value through calculation.
In the embodiment of the present application, the liquid medium in the millimeter wave calorimetric microwave power meter is purified water, alcohol, kerosene or diethyl ether.
Wherein, in this application embodiment, millimeter wave calorimetric microwave power meter mesocycle constant temperature module includes: a thermostat, a liquid medium transmission channel and a circulating pump; the head end and the tail end of the liquid medium transmission channel are respectively connected with the load liquid inlet and the load liquid outlet, the thermostat is used for controlling the temperature of liquid, and the circulating pump is used for generating circulating power.
In the embodiment of the present application, in the millimeter wave calorimetric microwave power meter, temperature data measured by 2 temperature measurement modules and flow data measured by a flowmeter and a controller module are collected into a computer or an embedded system, and a microwave power value is obtained through calculation, specifically:
according to the thermodynamic formula:
Q＝C·m·ΔT (1)
wherein: q heat, power, in joules (J)
Specific heat capacity, assuming that the medium is water, the specific heat capacity of water is as follows: 4200 Job/(kg. degree. C.), (J/(kg. degree. C.))
m is mass in kilogram (kg)
Delta T is the absolute value of the temperature change in degrees centigrade and DEG C.
After transformation, the formula (1) can be changed into:
P＝70·Δv·ΔT (2)
p is the measured power value in watts and Δ v is the flow rate in units of: liter/minute (L/min)
According to the formula (2), the power can be conveniently obtained by calculating the measured temperature difference and the water flow.
In the embodiment of the application, a method for measuring medium and low power in a calorimetric millimeter wave is further provided based on a millimeter wave calorimetric microwave power meter, and the method comprises the following steps:
step 1: calibrating the low power measurement system;
step 2: connecting a millimeter wave power source to be tested with the load, and transmitting millimeter waves generated by the millimeter wave power source to be tested to the load;
and step 3: controlling the temperature and flow rate of the liquid through a circulating constant temperature module;
and 4, step 4: the reason is that the data acquisition and post-processing module acquires the temperature data measured by the 2 temperature measurement modules and the flow data measured by the flowmeter and the controller module, and the microwave power value of the millimeter wave power source to be measured is calculated based on the acquired data.
The load in the millimeter wave calorimetric microwave power meter is of a cavity structure, a millimeter wave absorbing material composed of carbon powder and graphite nano materials is arranged in the cavity, the energy of millimeter waves is converted into heat energy in the absorbing material, and then the heat energy is transferred to a liquid medium in a winding liquid channel through the cavity, wherein the liquid medium can be water, alcohol, kerosene, ether and the like.
The millimeter wave calorimetric microwave power meter overcomes the problems that the millimeter wave power from a few watts to a few hundred watts cannot be measured by a direct measurement method and a high-power water load method, and the precision of a coupling measurement method is not enough.
The millimeter wave calorimetric microwave power meter adopts the constant temperature module in the circulating liquid channel, ensures the constant temperature of the liquid at the inlet of the power absorption module, ensures the stability of the inlet temperature, is favorable for the stability of a temperature measurement system, and is favorable for improving the precision and the stability of power measurement.
The millimeter wave calorimetric microwave power meter adopts an ultrahigh precision temperature measurement module, a high precision low flow rate flowmeter and a controller to realize millimeter wave calorimetric measurement of several watts to several hundred watts.
While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (9)
1. A load for a millimeter wave calorimeter, wherein the load comprises:
the microwave dry load, the liquid circulation and heat conduction channel, the liquid channel inlet, the liquid channel outlet, the waveguide mode converter, the heat insulation device and the sealed shell;
the heat insulation device and the sealing shell are both cavity bodies, the sealing shell is fixed in an inner cavity of the heat insulation device, the microwave dry load is installed in a cavity of the sealing shell, the input end of the waveguide mode converter extends out of the heat insulation device, the output end of the waveguide mode converter is connected with a microwave inlet of the microwave dry load, and the waveguide mode converter is used for converting the microwave inlet of the microwave dry load into a waveguide interface with a standard specification; be liquid circulation and heat conduction passageway between load and the sealed casing inner wall are done to the microwave, is equipped with liquid channel entry and liquid channel export between heat-proof device and the sealed casing, and the load is done to the microwave includes: the wave absorbing material comprises a metal cavity and a solid wave absorbing material, wherein the solid wave absorbing material is positioned in the metal cavity.
2. The load of claim 1, wherein the metal cavity is cylindrical and the solid absorbing material is located on the inner wall of the cylinder.
3. The load for the millimeter wave calorimetric microwave power meter according to claim 1, wherein the solid wave-absorbing material is silicon carbide or carbon powder.
4. The load for the millimeter wave calorimetric microwave power meter according to claim 1, wherein the liquid medium in the liquid circulation and heat conduction channel is one of water, alcohol, kerosene and ether.
5. The load for a millimeter wave calorimetric microwave power meter according to claim 1, wherein the liquid channel inlet is remote from a portion of the microwave dry load where heat is generated, and the liquid channel outlet is remote from the portion of the microwave dry load interface.
6. The load for a millimeter wave calorimetric microwave power meter according to claim 1, wherein the liquid circulation and heat conduction channel is helical.
7. The load for the millimeter wave calorimetric microwave power meter according to claim 1, wherein the heat insulation device is a cuboid cavity structure and is made of a heat insulation material or a metal vacuum process, the microwave dry load, the liquid circulation and the heat conduction channel are wrapped in the load, and a liquid channel interface is reserved, and the microwave dry load interface can be connected with the outside.
8. The load of claim 1, wherein the liquid circulation and the heat conduction channel are closely attached to the heat generating portion of the solid wave-absorbing material.
9. The load for the millimeter wave calorimetric microwave power meter according to any one of claims 1 to 8, wherein the millimeter wave calorimetric microwave power meter comprises:
the load module, the circulating constant temperature module, the 2 temperature measuring modules, the data acquisition and post-processing module, the flowmeter module and the controller module are arranged in the pipeline;
the load is of a cavity structure, the cavity structure absorbs and converts electromagnetic field energy of millimeter waves generated by the millimeter wave power source to be tested into heat and transfers the heat to the cavity wall, and a liquid medium channel is arranged on the cavity wall;
the circulating constant temperature module is used for generating liquid circulation, continuously taking away heat generated by the load and controlling the temperature of the liquid at the inlet of the load to be constant;
the 2 temperature measuring modules are respectively used for measuring the temperature of liquid flowing into the load inlet and the temperature of liquid flowing out of the load outlet;
a flow meter and controller module for controlling and measuring the flow of the liquid;
and the data acquisition and post-processing module is used for acquiring the temperature data measured by the 2 temperature measurement modules and the flow data measured by the flowmeter and the controller module into a computer or an embedded system, and obtaining the microwave power value through calculation.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201910516309.9A CN110133367B (en) | 2019-06-14 | 2019-06-14 | Load for millimeter wave calorimetric microwave power meter |
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| CN110133367B true CN110133367B (en) | 2020-09-08 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112510379B (en) * | 2020-12-08 | 2021-08-10 | 四川大学 | Water load capable of efficiently absorbing microwave energy |
| CN113552413B (en) * | 2021-07-30 | 2022-10-28 | 中国计量科学研究院 | Resistance tube type high-power sensor for microwave high-power measurement system |
| CN114264889B (en) * | 2021-12-16 | 2023-07-21 | 中国工程物理研究院应用电子学研究所 | High-power millimeter wave power measurement calibration device |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN1010892B (en) * | 1986-03-10 | 1990-12-19 | 中国科学院电子学研究所 | Milimeterwave full band power meter |
| CN100578236C (en) * | 2007-10-12 | 2010-01-06 | 核工业西南物理研究院 | M-w grade microwave power instrumentation system based on calorimetric method |
| CN105425026A (en) * | 2014-12-30 | 2016-03-23 | 北京无线电计量测试研究所 | Novel sealed constant-temperature double-load waveguide calorimeter |
| CN108110391B (en) * | 2016-12-14 | 2021-03-02 | 北京无线电计量测试研究所 | Coaxial water load for medium and high power calorimeter |
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Inventor after: Wang Bin Inventor after: Meng Lin Inventor after: Yin Yong Inventor after: Li Hailong Inventor after: Yuan Xuesong Inventor before: Wang Bin Inventor before: Meng Lin Inventor before: Yin Yong Inventor before: Li Haikong Inventor before: Yuan Xuesong |
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