Thin film technology-based integrated calorimetric load and power measurement method

Abstract

The invention relates to the technical field of millimeter wave power measurement, and provides an integrated calorimetric load based on a thin film technology and a power measurement method. The integrated calorimetric load comprises a waveguide tube and a chip absorber arranged outside the waveguide tube, the chip absorber comprises a silicon-based thin film layer and a functional thin film layer located on the silicon-based thin film layer, and the functional thin film layer comprises a first resistive thin film layer used as a direct-current heating source and a second resistive thin film layer used for measuring temperature. According to the technical scheme, the technical problem that an absorber with good matching characteristics and high replacement efficiency is difficult to design according to a traditional design thought when the signal frequency rises to a millimeter wave frequency band and even a terahertz frequency band in the prior art is solved.

Description

Technical Field

[0001] This invention belongs to the field of millimeter-wave power measurement technology, and more specifically, relates to an integrated calorimetric load and power measurement method based on thin-film technology. Background Technology

[0002] Power is one of the most fundamental parameters in the millimeter-wave field and an important parameter characterizing signal properties. The measurement of power parameters in the millimeter-wave and even terahertz frequency bands is based on converting millimeter-wave energy into energy forms such as heat, force, DC, or low-frequency electrical signals, and then measuring them. A calorimeter is a device that obtains the millimeter-wave power value by measuring the temperature change of a calorimetric load after absorbing DC or millimeter-wave power. Based on the DC / millimeter-wave power substitution principle, it assumes that DC power and millimeter-wave power have the same thermal effect, and thus the value of millimeter-wave power can be traced back to DC power through temperature or temperature difference measurements. Therefore, it is commonly used as a standard for millimeter-wave power.

[0003] As the core component of calorimetric measurements, the calorimetric load is also a key component for realizing the DC / millimeter-wave power substitution principle. Its main functions are to absorb millimeter-wave power and to achieve accurate substitution of millimeter-wave / DC power. Based on this, there are two basic requirements for the calorimetric load: first, it must have good matching characteristics and high millimeter-wave / DC power substitution efficiency; second, the mass of the calorimetric load needs to be appropriately reduced.

[0004] Traditional waveguide calorimetric loads typically consist of a waveguide, an absorber, and a DC heating source. The absorber is usually a wedge-shaped or cone-shaped absorbing material placed inside the waveguide. Currently, as signal frequencies rise to millimeter-wave and even terahertz bands, waveguide dimensions are decreasing, making it extremely difficult to design absorbers with both good matching characteristics and high substitution efficiency using traditional methods. This has become a major technical bottleneck in high-frequency calorimetric measurements. Summary of the Invention

[0005] The purpose of this invention is to provide an integrated calorimetric load and power measurement method based on thin-film technology, thereby solving or at least alleviating one or more of the above-mentioned problems and other problems existing in the prior art.

[0006] The technical solution of the present invention is as follows:

[0007] This invention proposes an integrated calorimetric load based on thin film technology, comprising: a waveguide and a sheet absorber disposed outside the waveguide, the sheet absorber comprising a silicon-based thin film layer and a functional thin film layer thereon, the functional thin film layer comprising a first resistive thin film layer used as a DC heating source and a second resistive thin film layer used for temperature measurement.

[0008] As a further technical solution, the angle between the axis of the waveguide and the surface of the sheet absorber is ≤15°.

[0009] As a further technical solution, the wall thickness of the waveguide is ≤0.1mm.

[0010] As a further technical solution, the functional thin film layer comprises, from bottom to top:

[0011] A metal thin film layer located on the silicon-based thin film layer;

[0012] A first insulating film layer located on the metal film layer;

[0013] The first resistive thin film layer is located at one end of the first insulating thin film layer;

[0014] The second resistive thin film layer is located at the other end of the first insulating thin film layer;

[0015] A second insulating film layer is located on the first resistive thin film layer and the second resistive thin film layer.

[0016] As a further technical solution, the metal thin film layer is a titanium thin film layer with a thickness of 350-400 nm.

[0017] As a further technical solution, the first insulating film layer and the second insulating film layer are each independently silicon dioxide film layers, and the thickness of the first insulating film layer and the second insulating film layer are each independently 500-550 nm.

[0018] As a further technical solution, the first resistive thin film layer is a NiCr metal thin film layer, and the resistance value of the NiCr metal thin film layer is 500 to 550 Ω.

[0019] As a further technical solution, the second resistive thin film layer is a Pt metal thin film layer, and the resistance value of the Pt metal thin film layer is 100 to 150 Ω.

[0020] As a further technical solution, the sheet absorber is bonded to the outside of the waveguide.

[0021] This invention also proposes a power measurement method, employing the aforementioned integrated calorimetric load based on thin-film technology, comprising:

[0022] A millimeter-wave power signal is input to the input end of the waveguide;

[0023] Apply DC power to the first resistive thin film layer;

[0024] Temperature difference is measured using a second resistive thin film layer;

[0025] The millimeter-wave power signal is traced back to the corresponding DC power based on the temperature difference.

[0026] The beneficial effects of this invention are as follows:

[0027] In existing technologies, absorbers are generally wedge-shaped or cone-shaped absorbing materials placed inside waveguides. This invention overcomes this technological bias by placing a thin-film-based sheet absorber outside the waveguide, solving the technical challenge of designing absorbers with both good matching characteristics and high substitution efficiency using traditional design approaches as signal frequencies increase to millimeter-wave and even terahertz bands. The integrated calorimetric load in this invention is suitable for power measurement in millimeter-wave and even terahertz bands. Specifically:

[0028] (1) The integrated calorimetric load of the present invention has high consistency and repeatability, which can ensure that the working load and the reference load have the same microwave and thermal characteristics, and can maximize the temperature distribution consistency between DC heating and microwave heating. It has the characteristics of integrated processing and molding, good microwave characteristics, high substitution efficiency, and high repeatability stability.

[0029] (2) The plate absorber in this invention has both DC heating and temperature measurement functions. The first resistive thin film layer, which serves as the DC heating source, is deposited on the load absorber, realizing the integration of DC heating and millimeter-wave power absorption, and maximizing the heating efficiency of DC power.

[0030] (3) The present invention selects thin film resistive elements as DC heating source materials. They have a small temperature coefficient of resistance, high stability, and are easy to use for a long time. Attached Figure Description

[0031] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. Obviously, the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0032] Figure 1 This is a schematic diagram of the structure of an integrated calorimetric load according to one embodiment of the present invention;

[0033] Figure 2 for Figure 1 A schematic diagram of the structure of a medium-sized absorber.

[0034] Reference numerals: 1. Waveguide; 2. Sheet absorber; 21. Silicon-based thin film layer; 22. Metal thin film layer; 23. First insulating thin film layer; 24. First resistive thin film layer; 25. Second resistive thin film layer; 26. Second insulating thin film layer. Detailed Implementation

[0035] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0036] It should be understood that, unless the context clearly indicates otherwise, the terms "comprising," "including," or "having" as used herein refer to the presence of a particular element, but do not exclude the presence or addition of one or more other elements. Furthermore, as used herein, "comprising" and / or "including" specify the presence of shapes, numbers, steps, operations, members, elements, and / or combinations thereof, and do not exclude the presence or addition of one or more other shapes, numbers, operations, elements, and / or combinations thereof.

[0037] In this invention, the numerical range indicated by "~" refers to the range of values ​​specified as the lower limit and upper limit, respectively, before or after the term. When multiple values ​​for the upper or lower limit of any numerical range are mentioned, the range disclosed herein can be understood as a range with any one of the mentioned upper limit values ​​as its upper limit and any one of the mentioned lower limit values ​​as its lower limit.

[0038] The following will describe in detail an integrated calorimetric load and power measurement method based on thin-film technology according to an embodiment of the present invention.

[0039] According to one aspect of the present invention, an integrated calorimetric load based on thin film technology is proposed, comprising: a waveguide 1 and a sheet absorber 2 disposed outside the waveguide 1, the sheet absorber 2 comprising a silicon-based thin film layer 21 and a functional thin film layer thereon, the functional thin film layer comprising a first resistive thin film layer 24 used as a DC heating source and a second resistive thin film layer 25 used for temperature measurement.

[0040] Please refer to Figure 1 and Figure 2 . Figure 1 A schematic diagram of an integrated calorimetric load. Figure 2 for Figure 1 A schematic diagram of the structure of the plate absorber 2. In this invention, the waveguide 1 can be rectangular, elliptical, circular, etc., preferably rectangular. The dimensions of the waveguide 1 meet international standards such as IEC 60153-2:2025 and IEC 60153-4:2022, depending on its shape. The waveguide 1 can be made of thin-walled stainless steel or thin-walled nickel-based alloy. To reduce ohmic loss and improve conductivity, gold can be plated on the inner wall of the waveguide 1. In the plate absorber 2, the functional thin film layer can be grown on the silicon-based thin film layer 21 by vapor deposition, such as magnetron sputtering or pulsed laser deposition.

[0041] In one embodiment of the present invention, the angle between the axis of the waveguide 1 and the surface of the sheet absorber 2 is ≤15°, preferably 9° to 15°, for example, including but not limited to 9°, 10°, 11°, 12°, 13°, 14°, and 15°.

[0042] In this invention, setting the angle between the axis of the waveguide 1 and the surface of the plate absorber 2 to ≤15° optimizes impedance matching, reduces reflection, lowers multipath interference, ensures good microwave matching in the millimeter-wave and even terahertz frequency bands, and further improves power measurement accuracy. When the angle is >15°, the power measurement accuracy decreases significantly; when the angle is 9° to 15°, the power measurement accuracy can be further improved.

[0043] In one embodiment of the present invention, the wall thickness of waveguide 1 is ≤0.1mm.

[0044] In this invention, when the wall thickness of the waveguide 1 is ≤0.1mm, from a transmission perspective, it can reduce additional loss and interference to millimeter-wave signals, ensuring signal integrity; from a structural design perspective, it can make the overall structure lighter and more compact, facilitating equipment miniaturization. Furthermore, the thinner wall makes it easier to process and shape, reducing manufacturing difficulty and cost, and meeting the comprehensive requirements for performance, size, and cost in practical applications.

[0045] In one embodiment of the present invention, the functional thin film layer comprises, from bottom to top:

[0046] Metal thin film layer 22 located on silicon-based thin film layer 21;

[0047] The first insulating thin film layer 23 is located on the metal thin film layer 22;

[0048] The first resistive thin film layer 24 is located at one end of the first insulating thin film layer 23;

[0049] The second resistive thin film layer 25 is located at the other end of the first insulating thin film layer;

[0050] The second insulating film layer 26 is located on the first resistive thin film layer 24 and the second resistive thin film layer 25.

[0051] In this invention, the thickness of the silicon-based thin film layer 21 is 0.5 to 1 mm, for example, including but not limited to 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, and 1 mm. The metal thin film layer 22 facilitates electron conduction, providing a stable conductive foundation for other functional thin film layers and assisting in DC heating and temperature measurement, thus optimizing overall electrical performance. The first insulating thin film layer 23 effectively isolates the metal thin film layer 22 from the first resistive thin film layer 24 and the second resistive thin film layer 25, preventing short circuits, ensuring independent operation of each layer, guaranteeing accurate operation of DC heating and temperature measurement functions, and improving stability. The first resistive thin film layer 24, as a DC heating source, can precisely control the heating power, realizing the correlation between DC and millimeter-wave heating, and providing thermal effect simulation for power measurement. The second resistive thin film layer 25, with its resistance changing with temperature, can accurately measure temperature differences, providing accuracy assurance for millimeter-wave power tracing. The second insulating thin film layer 26 protects the first resistive thin film layer 24 and the second resistive thin film layer 25 from external interference, stabilizes the internal structure, ensures long-term stable operation of the integrated calorimetric load, and improves its overall reliability.

[0052] In one embodiment of the present invention, the metal thin film layer 22 is a titanium thin film layer with a thickness of 350-400 nm, for example, including but not limited to 350 nm, 360 nm, 370 nm, 380 nm, 390 nm, and 400 nm.

[0053] In this invention, a titanium thin film layer with a thickness of 350–400 nm is preferably used as the metal thin film layer 22. Titanium has strong adhesion and can firmly connect the silicon substrate to other layers. This thickness range ensures good conductivity, aids in electron transport, and is not too thick to avoid increasing costs or affecting overall performance, thus laying the foundation for stable operation of the integrated calorimetric load.

[0054] In one embodiment of the present invention, the first insulating film layer 23 and the second insulating film layer 26 are each independently silicon dioxide film layers, and the thickness of the first insulating film layer 23 and the second insulating film layer 26 are each independently 500-550 nm, for example, including but not limited to 500 nm, 510 nm, 520 nm, 530 nm, 540 nm, and 550 nm.

[0055] The first insulating film layer 23 and the second insulating film layer 26 of this invention are preferably silicon dioxide film layers with a thickness of 500-550 nm. Silicon dioxide film layers have excellent insulating properties, effectively isolating the functional layers and preventing short circuits. Furthermore, this thickness ensures both insulation performance and overall structural stability, providing a favorable environment for the stable operation of the resistive layer and improving the reliability of the integrated calorimetric load.

[0056] In one embodiment of the present invention, the first resistive thin film layer 24 is a NiCr metal thin film layer with a resistance value of 500 to 550 Ω, for example, including but not limited to 500 Ω, 510 Ω, 520 Ω, 530 Ω, 540 Ω, and 550 Ω.

[0057] This invention preferably uses a NiCr metal thin film layer as the first resistive thin film layer 24 for the DC heating source, and more preferably a Ni80Cr20 metal thin film layer, because Ni80Cr20 has excellent oxidation resistance and thermal stability, and can work stably in complex environments. When the resistance value of the NiCr metal thin film layer is 500-550Ω, the DC heating power can be moderate, achieving accurate simulation of the heat absorption effect of millimeter-wave power, providing a reliable basis for temperature difference-based millimeter-wave power measurement, and ensuring the accuracy and stability of the measurement results. Within this range, it avoids both insufficient heat generation due to too small a resistance value, which would prevent effective simulation of the heat conversion of millimeter-wave power absorption and cause measurement deviation, and excessively large a resistance value, which would lead to too rapid a heating rate, making it difficult to accurately control the temperature and thus affecting the measurement accuracy.

[0058] In one embodiment of the present invention, the second resistive thin film layer 25 is a Pt metal thin film layer with a resistance value of 100 to 150 Ω, for example, including but not limited to 100 Ω, 110 Ω, 120 Ω, 130 Ω, 140 Ω, and 150 Ω.

[0059] This invention preferably uses a Pt metal thin film layer as the second resistive thin film layer 25. The Pt metal thin film layer has a stable temperature coefficient of resistance and good linearity, accurately reflecting temperature changes and providing a reliable basis for temperature difference measurement. Setting the resistance value of the Pt metal thin film layer in the range of 100–150 Ω ensures accurate measurement of resistance changes while reducing the burden on the measurement circuit, ensuring accurate and stable power measurement based on temperature difference. If the resistance value is too small, the resistance change is difficult to measure accurately when the temperature changes, resulting in a large temperature difference measurement error and affecting the accuracy of millimeter-wave power tracing. If the resistance value is too large, the power consumption of the measurement circuit increases, potentially introducing additional thermal effects that interfere with the measurement. Furthermore, excessively large resistances place higher demands on the measurement circuit, increasing measurement complexity.

[0060] In one embodiment of the present invention, the sheet absorber 2 is bonded to the outside of the waveguide 1.

[0061] In this invention, the sheet absorber 2 can be bonded and fixed to the outside of the waveguide 1 using insulating adhesive. Epoxy resin insulating adhesive is preferred due to its excellent insulation properties, effectively preventing electrical short circuits between the waveguide 1 and the sheet absorber 2, ensuring independent normal operation of each component. Furthermore, epoxy resin insulating adhesive has high bonding strength, firmly fixing the sheet absorber 2 and maintaining its stability during equipment operation, resisting the influence of external forces such as vibration and impact, and ensuring measurement stability. Moreover, epoxy resin insulating adhesive has good chemical stability, is not easily affected by environmental factors such as humidity and temperature changes, extending the service life of the equipment and providing a guarantee for the long-term reliable operation of the integrated calorimetric load.

[0062] According to another aspect of the present invention, the present invention also proposes a method for power measurement using the above-described integrated calorimetric load based on thin-film technology, comprising:

[0063] A millimeter-wave power signal is input to the input end of waveguide 1;

[0064] DC power is applied to the first resistive thin film layer 24;

[0065] Temperature difference is measured through the second resistive thin film layer 25;

[0066] The millimeter-wave power signal is traced back to the corresponding DC power based on the temperature difference.

[0067] Specifically, the millimeter-wave power signal is transmitted to the input end of waveguide 1 via a waveguide adapter. The connection process must ensure a tight seal to prevent signal leakage or reflection, which could affect measurement accuracy. Next, the lead wire from the first resistive thin film layer 24 is connected to a DC power supply. The power applied to the first resistive thin film layer 24 is controlled by adjusting the output power of the DC power supply, causing the first resistive thin film layer 24 to generate heat equivalent to the millimeter-wave power absorption. Then, the lead wire from the second resistive thin film layer 25 is connected to a resistance measuring instrument to monitor the resistance change of the second resistive thin film layer 25 in real time. Based on the temperature coefficient of resistance of the second resistive thin film layer 25, the resistance change is converted into a temperature change. By averaging multiple measurements, measurement errors are reduced, and the accuracy of temperature difference measurement is improved. Finally, the measured temperature difference is correlated with the applied DC power, accurately tracing the millimeter-wave power signal to the corresponding DC power source.

[0068] The following will describe in detail, with reference to examples, an integrated calorimetric load and power measurement method based on thin-film technology according to the present invention. The embodiments of the present invention described below can be modified in various forms, and therefore the scope of the invention should not be construed as limited to the embodiments described in detail below. The embodiments are provided to help those skilled in the art to more readily understand the present invention.

[0069] Example 1

[0070] like Figure 1 The integrated calorimetric load shown includes a waveguide 1 and a sheet-type absorber layer 2 bonded to the outside of the waveguide 1 with epoxy resin insulating adhesive. The angle between the axis of the waveguide 1 and the surface of the sheet-type absorber 2 is 15°. The waveguide 1 is a rectangular waveguide, with internal dimensions of 2.54mm × 1.27mm as determined by IEC 60153-2:2025. It is made of thin-walled 316L stainless steel with a wall thickness of 0.1mm, and its inner wall is gold-plated to reduce ohmic loss and improve conductivity. A schematic diagram of the sheet-type absorber layer 2 is shown below. Figure 2 As shown, its principle and connection are as follows: First, a titanium thin film layer with a thickness of 350 nm is grown on a 0.5 mm thick silicon-based thin film layer 21 by magnetron sputtering as a metal thin film layer 22, using titanium metal to ensure good conductivity; Second, a silicon dioxide thin film layer with a thickness of 500 nm is grown on the metal thin film layer 22 by magnetron sputtering as a first insulating thin film layer 23 to prevent short circuits; Third, a Ni80Cr20 metal thin film layer with a resistance of 500 Ω is grown on one end of the first insulating thin film layer 23 by magnetron sputtering as a first insulating thin film layer 23. The resistive thin film layer 24 is used for DC heating to simulate the heat absorption effect of millimeter-wave power. Fourth, a Pt metal thin film layer with a resistance of 100Ω is grown on the other end of the first insulating thin film layer 23 by magnetron sputtering as a second resistive thin film layer 25. The temperature difference is measured by utilizing its stable temperature coefficient of resistance and good linearity. Fifth, a silicon dioxide thin film layer with a thickness of 500nm is grown on the first resistive thin film layer 24 and the second resistive thin film layer 25 by magnetron sputtering as a second insulating thin film layer 26 to protect the resistive layer and ensure structural stability.

[0071] In millimeter-wave power measurement, firstly, the millimeter-wave power signal is input through the input end of waveguide 1, ensuring a tight connection to prevent signal leakage or reflection; secondly, the wires leading out of the first resistive thin film layer 24 are connected to a DC power supply, and the power applied to the first resistive thin film layer 24 is controlled by adjusting the output power of the DC power supply; thirdly, the wires leading out of the second resistive thin film layer 25 are connected to a resistance measuring instrument to monitor the resistance change of the second resistive thin film layer 25 in real time, and the resistance change is converted into a temperature change based on the resistance temperature coefficient characteristics of the second resistive thin film layer 25. By taking the average of multiple measurements, the measurement error is reduced and the accuracy of temperature difference measurement is improved; fourthly, the measured temperature difference is correlated with the applied DC power, accurately tracing the millimeter-wave power signal to the corresponding DC power, thus completing the millimeter-wave power measurement.

[0072] This invention solves the technical challenge of designing absorbers with both good matching characteristics and high substitution efficiency by placing a thin-film-based sheet absorber outside the waveguide. This is achieved through traditional design approaches that struggle to create absorbers with both good matching characteristics and high substitution efficiency as signal frequencies increase to millimeter-wave and even terahertz bands. The integrated calorimetric load in this invention is suitable for power measurement in the millimeter-wave and even terahertz bands.

[0073] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An integrated calorimetric load based on thin-film technology, characterized in that, include: A waveguide and a sheet absorber disposed outside the waveguide, the sheet absorber comprising a silicon-based thin film layer and a functional thin film layer thereon, the functional thin film layer comprising a first resistive thin film layer serving as a DC heating source and a second resistive thin film layer serving as a temperature measurement.

2. The integrated calorimetric load based on thin-film technology according to claim 1, characterized in that, The angle between the axis of the waveguide and the surface of the plate absorber is ≤15°.

3. The integrated calorimetric load based on thin-film technology according to claim 1, characterized in that, The wall thickness of the waveguide is ≤0.1mm.

4. The integrated calorimetric load based on thin-film technology according to claim 1, characterized in that, The functional thin film layer comprises, from bottom to top: A metal thin film layer located on the silicon-based thin film layer; A first insulating film layer located on the metal film layer; The first resistive thin film layer is located at one end of the first insulating thin film layer; The second resistive thin film layer is located at the other end of the first insulating thin film layer; A second insulating film layer is located on the first resistive thin film layer and the second resistive thin film layer.

5. The integrated calorimetric load based on thin-film technology according to claim 4, characterized in that, The metal thin film layer is a titanium thin film layer with a thickness of 350-400 nm.

6. The integrated calorimetric load based on thin-film technology according to claim 4, characterized in that, The first insulating film layer and the second insulating film layer are each independently silicon dioxide film layers, and the thickness of the first insulating film layer and the second insulating film layer are each independently 500-550 nm.

7. The integrated calorimetric load based on thin-film technology according to claim 4, characterized in that, The first resistive thin film layer is a NiCr metal thin film layer, and the resistance value of the NiCr metal thin film layer is 500 to 550 Ω.

8. The integrated calorimetric load based on thin-film technology according to claim 4, characterized in that, The second resistive thin film layer is a Pt metal thin film layer, and the resistance value of the Pt metal thin film layer is 100 to 150 Ω.

9. The integrated calorimetric load based on thin-film technology according to claim 1, characterized in that, The sheet absorber is bonded to the outside of the waveguide.

10. A power measurement method, employing the integrated calorimetric load based on thin-film technology as described in any one of claims 1 to 9, characterized in that, include: A millimeter-wave power signal is input to the input end of the waveguide; Apply DC power to the first resistive thin film layer; Temperature difference is measured using a second resistive thin film layer; The millimeter-wave power signal is traced back to the corresponding DC power based on the temperature difference.

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