A low-temperature waveguide noise source

Abstract

The present invention provides a low-temperature waveguide noise source. The noise source comprises: a rectangular waveguide, a matching load, and a temperature control device; the rectangular waveguide comprises an input section, a transition section, and an output section connected in sequence; the matching load is disposed within the input section; the input section is used to be placed in liquid nitrogen to cool the matching load; the thermal conductivity of the transition section is lower than that of the input and output sections; the temperature control device is disposed in the output section; and the temperature control device is used to control the temperature of the output end of the output section to a set temperature. The present invention can control the output end temperature to be constant through the temperature control device; the transition section reduces heat conduction between the input and output ends, reduces the impact of the input end on the output end temperature, and ensures stable output of low-reflection coefficient thermal noise. At the same time, the transition section reduces heat loss at the output end, reducing the power consumption of the temperature control device. In addition, the thermal insulation effect of the transition section can reduce the heat gain at the input end, thereby reducing the volatilization of liquid nitrogen used to cool the input end, saving the amount of liquid nitrogen used.

Description

Technical Field

[0001] The present invention relates to the technical field of noise measurement, and in particular to a low-temperature waveguide noise source. Background Art

[0002] The magnitude of thermal noise depends on the object's thermodynamic temperature. Thermal noise standard sources based on thermodynamic temperature are used for noise parameter measurement and metrological calibration, and are widely used in a wide range of fields, including aerospace tracking and control, radio astronomy, radar, microwave remote sensing, electronic countermeasures, and communications. Depending on the temperature, thermal noise standard sources are divided into cold sources and hot sources. The cold source's matching load is placed inside the input end of a rectangular waveguide, which is cooled by liquid nitrogen. The matching load outputs standard thermal noise at 77.3K through the waveguide's output end.

[0003] However, the input end of the rectangular waveguide placed in liquid nitrogen affects the temperature of the output end, making the temperature of the output end lower than room temperature, thereby affecting the stable low reflection coefficient thermal noise output by the noise source. Summary of the Invention

[0004] An embodiment of the present invention provides a low-temperature waveguide noise source to solve the problem that the input end of a rectangular waveguide affects the temperature of the output end.

[0005] In a first aspect, embodiments of the present invention provide a low-temperature waveguide noise source, comprising: a rectangular waveguide, a matching load, and a temperature control device. The rectangular waveguide comprises an input section, a transition section, and an output section, which are connected in sequence. The matching load is disposed within the input section. The input section is configured to be placed in liquid nitrogen to cool the matching load. The thermal conductivity of the transition section is lower than that of the input and output sections. The temperature control device is disposed in the output section. The temperature control device is configured to control the temperature of the output end of the output section to a predetermined temperature.

[0006] In a possible implementation, the thickness of the waveguide wall of the transition section is smaller than the thickness of the waveguide walls of the input section and the output section.

[0007] In a possible implementation, the transition section includes a first transition section, a first flange, a second flange, and a second transition section connected in sequence. A thermal insulation gasket is provided between the first flange and the second flange.

[0008] In a possible implementation, the thermal insulation gasket is a polytetrafluoroethylene gasket.

[0009] In a possible implementation, the thickness of the polytetrafluoroethylene gasket ranges from 0.1 mm to 0.2 mm.

[0010] In a possible implementation, a first heat-absorbing copper disk is provided on a side of the transition section close to the output section.

[0011] In one possible implementation, the temperature control device includes a heating resistor, a thermistor, and a shielding housing. The heating resistor and the output section are disposed within the shielding housing. The heating resistor is used to heat the output section. The shielding housing is used to shield electromagnetic interference generated by the heating resistor. The thermistor is disposed at the output end and is used to detect the temperature of the output end.

[0012] In a possible implementation, a second heat-absorbing copper disk is provided on a side of the output section close to the output end.

[0013] In one possible implementation, the noise source further includes a liquid nitrogen cooling device. The liquid nitrogen cooling device includes an internal insulation layer and an external structural layer. A through hole is defined in a sidewall of the liquid nitrogen cooling device, extending through the internal insulation layer and the external structural layer. The through hole is used to mount the rectangular waveguide. The input section is positioned within the liquid nitrogen cooling device. The transition section and the output section are positioned outside the liquid nitrogen cooling device.

[0014] In a possible implementation, the waveguide wall thickness of the transition section is 0.5 mm.

[0015] An embodiment of the present invention provides a low-temperature waveguide noise source, comprising: a rectangular waveguide, a matching load, and a temperature control device. The rectangular waveguide includes an input section, a transition section, and an output section, which are connected in sequence. The matching load is located within the input section. The input section is placed in liquid nitrogen to cool the matching load. The thermal conductivity of the transition section is lower than that of the input and output sections. A temperature control device is located in the output section. The temperature control device is used to control the temperature of the output end of the output section to a set temperature. The present application uses the temperature control device to maintain a constant temperature at the output end. By providing a transition section with poor thermal conductivity, heat conduction between the input and output ends is reduced, thereby reducing the impact of the input end on the output end temperature, thereby ensuring that the noise source outputs stable low-reflection coefficient thermal noise. Furthermore, the thermal insulation of the transition section reduces heat conduction from the output end to the input end, reducing heat loss at the output end, thereby reducing heating of the temperature control device and lowering the power consumption of the temperature control device. Furthermore, the thermal insulation of the transition section can reduce heat gain at the input end, thereby reducing the volatilization of liquid nitrogen used to cool the input end, thereby saving liquid nitrogen usage. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 11 is a schematic structural diagram of a low-temperature waveguide noise source provided by an embodiment of the present invention;

[0018] Figure 2 is a schematic diagram of the cross-sectional structure of a noise source provided by an embodiment of the present invention;

[0019] Figure 3 Schematic diagram of the structure of a noise source provided with a heat-insulating gasket according to an embodiment of the present invention;

[0020] Figure 4 1 is a schematic diagram of a cross-sectional structure of a noise source provided with a heat insulating gasket according to an embodiment of the present invention;

[0021] Figure 5 Schematic diagram of the noise source structure provided with a first heat-absorbing copper plate according to an embodiment of the present invention;

[0022] Figure 6 1 is a schematic diagram of a cross-sectional structure of a noise source provided with a first heat-absorbing copper plate according to an embodiment of the present invention;

[0023] Figure 7 is a schematic cross-sectional structural diagram of a temperature control device provided by an embodiment of the present invention;

[0024] Figure 8 Schematic diagram of the noise source structure provided with a second heat-absorbing copper plate according to an embodiment of the present invention;

[0025] Figure 9 1 is a schematic diagram of a cross-sectional structure of a noise source provided with a second heat-absorbing copper plate according to an embodiment of the present invention;

[0026] Figure 10 is a schematic cross-sectional structural diagram of a liquid nitrogen cooling device provided in an embodiment of the present invention;

[0027] Figure 11 2 is a schematic structural diagram of another noise source provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0028] To help those skilled in the art better understand this solution, the following will clearly describe the technical solutions in the embodiments of this solution in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of this solution, not all of it. Based on the embodiments of this solution, all other embodiments obtained by those skilled in the art without creative work should fall within the scope of protection of this solution.

[0029] Throughout the specification, claims, and accompanying figures of this solution, the term "including" and any variations thereof mean "including, but not limited to," and are intended to cover non-exclusive inclusions and are not limited to the examples listed herein. Furthermore, the terms "first" and "second," etc., are used to distinguish between different objects, not to describe a specific order.

[0030] The following is a detailed description of the implementation of the present invention with reference to the accompanying drawings:

[0031] The magnitude of thermal noise depends on the object's thermodynamic temperature. The cold source's matching load is placed inside a rectangular waveguide, one end of which is immersed in liquid nitrogen for cooling. The matching load outputs standard thermal noise at 77.3K. However, the input end of the rectangular waveguide, placed in liquid nitrogen, affects the temperature of the output end, causing it to fall below room temperature, thus affecting the stable low-reflection coefficient thermal noise output by the noise source.

[0032] Figure 1 A schematic structural diagram of a low-temperature waveguide noise source provided by an embodiment of the present invention; Figure 1 , the noise sources include:

[0033] Rectangular waveguide 1, matching load 2, and temperature control device 3. Rectangular waveguide 1 includes an input section 11, a transition section 12, and an output section 13, which are connected in sequence. Matching load 2 is located within input section 11. Input section 11 is placed in liquid nitrogen to cool matching load 2. The thermal conductivity of transition section 12 is lower than that of input section 11 and output section 13. Temperature control device 3 is located in output section 13. Temperature control device 3 is used to control the output end temperature of output section 13 to a set temperature.

[0034] The output end of the rectangular waveguide 1 is the input end of the input section 11. The output end of the rectangular waveguide 1 is the output end of the output section 13. The input and output ends of the rectangular waveguide 1 are closed, and a closed cavity is formed inside.

[0035] The input section 11 of the rectangular waveguide 1 is cooled with liquid nitrogen. Thermal noise generated by the matching load 2 is output through the output of the rectangular waveguide 1. The rectangular waveguide 1 is a hollow metal waveguide with a rectangular cross-section, designed to provide directional electromagnetic wave propagation within the tube. The matching load 2, placed within the input section 11 of the rectangular waveguide 1, generates electromagnetic waves at the target cooling temperature. These waves propagate within the rectangular waveguide 1 and are output through the output of the rectangular waveguide 1.

[0036] The transition section 12 of the rectangular waveguide 1 has a lower thermal conductivity than the input section 11 and the output section 13. That is, the amount of heat that can be conducted through the transition section 12 per unit time is lower than the amount of heat that can be conducted through the input section 11 and the output section 13 per unit time.

[0037] The rectangular waveguide 1 is typically made of metal, which has excellent thermal conductivity. When the temperatures at both ends are inconsistent, heat from the higher end is easily transferred to the lower end. The transition section 12 between the input section 11 and the output section 13 reduces heat conduction and acts as a thermal insulator. This reduces the amount of heat transferred from the output section 13, which is at room temperature, to the input section 11, which is cooled by liquid nitrogen. This reduces the temperature impact of the rectangular waveguide 1's input end on the output end.

[0038] Temperature fluctuations at the output end can affect the stable low-reflection coefficient thermal noise output by the noise source. Due to variations in ambient temperature and air convection, transition section 12 alone cannot ensure stable output temperature. Temperature control device 3, located in output section 13, is used to control the output end temperature of output section 13 to a set temperature. Exemplarily, temperature control device 3 is used to heat output section 13 to maintain the output end temperature at a set temperature. Exemplarily, the set temperature is room temperature. Exemplarily, the set temperature is 25 degrees Celsius.

[0039] A low-temperature waveguide noise source provided by an embodiment of the present invention controls the output temperature to be constant via a temperature control device 3. By providing a transition section 12 with poor thermal conductivity, heat conduction between the input and output ends is reduced, minimizing the impact of the input end on the output end temperature, thereby ensuring that the noise source outputs stable low-reflection coefficient thermal noise. Simultaneously, the thermal insulation provided by the transition section 12 reduces heat conduction from the output end to the input end, reducing heat loss at the output end, thereby reducing heating and power consumption of the temperature control device 3. Furthermore, the thermal insulation provided by the transition section 12 reduces heat gain at the input end, thereby reducing the volatilization of liquid nitrogen used to cool the input end and saving liquid nitrogen usage.

[0040] Figure 2 is a schematic diagram of the cross-sectional structure of the noise source provided by an embodiment of the present invention; Figure 2 :

[0041] In an optional embodiment, the waveguide wall thickness of the transition section 12 is smaller than the waveguide wall thickness of the input section 11 and the output section 13 .

[0042] The thickness of the waveguide wall of the transition section 12 is reduced, the cross-sectional area of ​​heat conduction is reduced, the amount of heat that can be conducted through the transition section 12 per unit time is reduced, the thermal conductivity becomes worse, and thus the transition section 12 can play a heat insulation role.

[0043] Exemplarily, the input section 11, transition section 12, and output section 13 of the rectangular waveguide 1 are connected end to end by welding. Exemplarily, the middle section of the rectangular waveguide 1 with uniform thickness is milled from the outside to the inside to reduce the thickness of the waveguide wall. The milled middle section serves as the transition section 12.

[0044] The transition section 12 with reduced waveguide wall thickness provided in the embodiment of the present invention has a simple structure and processing method. The rectangular waveguide 1 does not need to be equipped with other connecting devices, and the thermal noise and electromagnetic wave loss caused by the addition of connecting devices is small.

[0045] In an optional embodiment, the waveguide wall thickness of the transition section 12 is 0.5 mm.

[0046] Figure 3 Schematic diagram of the structure of a noise source provided with a heat-insulating gasket according to an embodiment of the present invention; Figure 4 Schematic diagram of the cross-sectional structure of a noise source provided with a heat insulating gasket according to an embodiment of the present invention; Figure 3 and Figure 4 :

[0047] In an optional embodiment, the transition section 12 includes a first transition section 121, a first flange 122, a second flange 123, and a second transition section 124 connected in sequence. A heat insulating gasket 125 is provided between the first flange 122 and the second flange 123.

[0048] The thermal insulation gasket 125 ensures that the first flange 122 and the second flange 123 are isolated from each other and do not directly contact each other, thereby reducing heat transfer and further reducing heat conduction between the input section 11 and the output section 13 .

[0049] Exemplarily, one end of the first transition section 121 is connected to the input section 11 , and the other end of the first transition section 121 is connected to the second transition section 124 via the first flange 122 , the thermal insulation gasket 125 , and the second flange 123 . The second transition section 124 is connected to the output section 13 .

[0050] For example, the heat-insulating gasket 125 is a ring-shaped structure with a hole in the center, which ensures that the thermal noise electromagnetic wave is transmitted from the first transition section 121 to the second transition section 124 and reduces the electromagnetic wave loss caused by the heat-insulating gasket 125 blocking.

[0051] Exemplarily, the first flange 122, the thermal insulation gasket 125, and the second flange 123 are fixed by fasteners. Exemplarily, the fasteners include bolts, nuts, screws, or clamps.

[0052] For example, a heat-insulating material with poor thermal conductivity is provided between the fastener and the flange. The fastener is not in direct contact with the flange to reduce heat transfer.

[0053] In an optional embodiment, the thermal insulation gasket 125 is a polytetrafluoroethylene gasket.

[0054] In an optional embodiment, the thickness of the polytetrafluoroethylene gasket ranges from 0.1 mm to 0.2 mm.

[0055] Figure 5Schematic diagram of the noise source structure provided with a first heat-absorbing copper plate according to an embodiment of the present invention; Figure 6 Schematic diagram of the cross-sectional structure of a noise source provided with a first heat-absorbing copper plate according to an embodiment of the present invention; Figure 5 and Figure 6 :

[0056] In an optional embodiment, a first heat-absorbing copper plate 126 is provided on a side of the transition section 12 near the output section 13. The first heat-absorbing copper plate 126 is disposed around the rectangular waveguide 1. A rectangular hole is defined in the center of the first heat-absorbing copper plate 126. The dimensions of the rectangular hole are consistent with the dimensions of the rectangular cross-section of the rectangular waveguide 1.

[0057] Exemplarily, the first heat absorbing copper plate 126 is disposed in the second transition section 124 .

[0058] Exemplarily, the first heat-absorbing copper disc 126 is composed of two semicircles with a rectangular notch at the center. Exemplarily, the two semicircles are connected by fasteners. Exemplarily, the rectangular waveguide 1 and the two semicircles of the first heat-absorbing copper disc 126 are connected by low-temperature structural adhesive. The detachable structure of the two semicircles facilitates adjustment of the position of the heat-absorbing copper discs according to the application scenario. Furthermore, the diameter of the first heat-absorbing copper disc 126 is much larger than the cross-sectional dimensions of the rectangular waveguide 1. This detachable structure facilitates the passage of the noise source through smaller holes, facilitating its installation and use.

[0059] Exemplarily, the first heat absorbing copper plate 126 is connected to the rectangular waveguide 1 by welding.

[0060] Exemplarily, the thickness of the first heat-absorbing copper plate 126 is 7 mm.

[0061] In this embodiment of the present invention, a first heat-absorbing copper disk 126 is provided on the side of the transition section 12 near the output section 13 to further absorb heat from the air, accelerate heat conduction between the air and the transition section 12, increase the temperature of the transition section 12, reduce heat conduction from the input section 11 to the transition section 12, and reduce the temperature impact of the input section 11 on the output section 13. At the same time, heat loss in the output section 13 is reduced, further reducing the power consumption of the temperature control device 3 of the output section 13.

[0062] Figure 7 is a schematic diagram of the cross-sectional structure of the temperature control device provided by an embodiment of the present invention; Figure 7 :

[0063] In an optional embodiment, the temperature control device 3 includes a heating resistor 31, a thermistor 32, and a shielding housing 33. The heating resistor 31 and the output section 13 are disposed within the shielding housing 33. The heating resistor 31 is used to heat the output section 13. The shielding housing 33 is used to shield the electromagnetic interference generated by the heating resistor 31. The thermistor 32 is disposed at the output end and is used to detect the temperature of the output end.

[0064] For example, the thermistor 32 is connected to a thermostat, which is connected to a heating power supply, which is connected to the heating resistor 32. The thermostat controls the on / off of the heating power supply according to a signal from the thermistor 32, thereby controlling the heating resistor 31 to heat.

[0065] For example, the heating resistor 31 is not in direct contact with the rectangular waveguide 1. Heat is conducted by thermal radiation to avoid excessive temperature at a certain point of the rectangular waveguide 1.

[0066] Exemplarily, the heating resistor 31 is two 24W gold-aluminum-shelled resistors. Exemplarily, the thermistor 32 is a PT100 platinum resistor.

[0067] By providing a shielding shell 33 , the embodiment of the present invention can shield the electromagnetic interference generated by the temperature control device 3 in noise measurement or noise calibration application scenarios, thereby reducing the impact of the temperature control device 3 on the noise measurement device or noise calibration device.

[0068] Figure 8 Schematic diagram of the noise source structure provided with a second heat-absorbing copper plate according to an embodiment of the present invention; Figure 9 Schematic diagram of the cross-sectional structure of a noise source provided with a second heat-absorbing copper plate according to an embodiment of the present invention; Figure 8 and Figure 9 :

[0069] In an optional embodiment, a second heat-absorbing copper plate 131 is provided on one side of the output section 13 near the output end. The second heat-absorbing copper plate 131 is disposed around the rectangular waveguide 1. A rectangular hole is provided at the center of the second heat-absorbing copper plate 131. The dimensions of the rectangular hole are consistent with the outer dimensions of the rectangular cross-section of the rectangular waveguide 1.

[0070] Exemplarily, the second heat-absorbing copper disc 131 is composed of two semicircles with a rectangular notch at the center. Exemplarily, the two semicircles are connected by fasteners. Exemplarily, the rectangular waveguide 1 and the two semicircles of the second heat-absorbing copper disc 131 are connected by low-temperature structural adhesive. The detachable structure of the two semicircles facilitates adjustment of the position of the heat-absorbing copper discs according to the application scenario. Furthermore, the diameter of the second heat-absorbing copper disc 131 is much larger than the cross-sectional dimensions of the rectangular waveguide 1. This detachable structure facilitates the passage of the noise source through smaller holes, facilitating its installation and use.

[0071] Exemplarily, the second heat-absorbing copper plate 131 is connected to the rectangular waveguide 1 by welding.

[0072] Exemplarily, the thickness of the second heat-absorbing copper plate 131 is 7 mm.

[0073] In the embodiment of the present invention, a second heat-absorbing copper disk 131 is provided on the side of the output section 13 close to the output end, thereby increasing the heat conduction surface area and accelerating the heat transfer between the heating resistor 31 and the rectangular waveguide 1. The output end temperature reaches a constant value more quickly, the noise source works efficiently, and the power consumption of the temperature control device 3 is reduced.

[0074] Figure 10 is a schematic diagram of the cross-sectional structure of the liquid nitrogen cooling device provided in an embodiment of the present invention; Figure 10 :

[0075] In an optional embodiment, the noise source further includes a liquid nitrogen cooling device 4. The liquid nitrogen cooling device 4 includes an inner insulation layer 41 and an outer structural layer 42. A through hole 43 is provided on the sidewall of the liquid nitrogen cooling device 4, extending through the inner insulation layer 41 and the outer structural layer 42. The through hole 43 is used to mount the rectangular waveguide 1. The input section 11 is located inside the liquid nitrogen cooling device 4. The transition section 12 and the output section 13 are located outside the liquid nitrogen cooling device 4.

[0076] Exemplarily, the material of the inner insulation layer 41 is thermal insulation foam. Exemplarily, the material of the outer structural layer 42 is aluminum.

[0077] For example, the inner insulation layer 41 is in the shape of a hollow cylinder, including a barrel body, a barrel bottom and a barrel cover. The barrel body and the barrel bottom are bonded by low-temperature resistant structural adhesive, and the barrel cover is detachable.

[0078] For example, the thermal insulation foam is processed into a cuboid with a length of 15 cm, a width of 15 cm and a height of 20 cm, and the inner and outer cylinders of the cuboid are cut using an electric heating wire. The bottom and cover of the barrel are then prepared using thermal insulation foam respectively, and finally the bottom and the barrel body are bonded using a low-temperature resistant structural adhesive.

[0079] Figure 11 is a structural diagram of another noise source provided by an embodiment of the present invention; Figure 11 :

[0080] In an optional embodiment, the input section 11 is placed in the liquid nitrogen of the liquid nitrogen cooling device 4, the transition section 12 is placed in the through hole 43 that penetrates the internal insulation layer 41 and the external structural layer 42, the external structural layer 42 is an aluminum shell, the output section 13 is placed outside the aluminum shell, the temperature control device 3 is arranged on the aluminum shell, and the heating resistor 31 is fixed on the outer wall of the aluminum shell.

[0081] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A low-temperature waveguide noise source, characterized in that: include: Rectangular waveguide, matching load and temperature control device; The rectangular waveguide comprises an input section, a transition section and an output section connected in sequence; The matching load is arranged inside the input section; the input section is used to be placed in liquid nitrogen to cool the matching load; The thermal conductivity of the transition section is lower than that of the input section and the output section; the thickness of the waveguide wall of the transition section is smaller than that of the waveguide wall of the input section and the output section; the transition section includes a first transition section, a first flange, a second flange, and a second transition section connected in sequence; a thermal insulation gasket is provided between the first flange and the second flange; the thermal insulation gasket is an annular structure with a hole in the center; The temperature control device is arranged in the output section; the temperature control device is used to control the output end temperature of the output section to be at a set temperature.

2. A low-temperature waveguide noise source according to claim 1, characterized in that: The thermal insulation gasket is a polytetrafluoroethylene gasket.

3. A low-temperature waveguide noise source according to claim 2, characterized in that: The thickness of the polytetrafluoroethylene gasket ranges from 0.1 mm to 0.2 mm.

4. A low-temperature waveguide noise source according to claim 1, characterized in that: A first heat-absorbing copper disk is provided on one side of the transition section close to the output section.

5. A low-temperature waveguide noise source according to claim 1, characterized in that: The temperature control device includes a heating resistor, a thermistor and a shielding shell; The heating resistor and the output section are arranged inside the shielding shell; the heating resistor is used to heat the output section; the shielding shell is used to shield the electromagnetic interference generated by the heating resistor; The thermistor is provided at the output end; the thermistor is used to detect the temperature of the output end.

6. A low-temperature waveguide noise source according to claim 5, characterized in that: A second heat-absorbing copper disk is provided on one side of the output section close to the output end.

7. A low-temperature waveguide noise source according to claim 1, characterized in that: The noise source further includes a liquid nitrogen cooling device; the liquid nitrogen cooling device includes an internal insulation layer and an external structural layer; The side wall of the liquid nitrogen cooling device is provided with a through hole penetrating the internal insulation layer and the external structural layer; The through hole is used to install the rectangular waveguide; the input section is placed inside the liquid nitrogen cooling device; and the transition section and the output section are placed outside the liquid nitrogen cooling device.

8. The low-temperature waveguide noise source according to claim 1, characterized in that: The waveguide wall thickness of the transition section is 0.5 mm.

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