Terahertz refrigeration low-noise receiving front end

Abstract

The embodiment of the invention provides a terahertz refrigeration low-noise receiving front end, and relates to the technical field of terahertz communication, and the receiving front end comprises a micro Dewar refrigeration cavity and a receiving front end body. The receiving front-end body comprises a front-stage device and a rear-stage device, and the front-stage device comprises an antenna and a low-noise amplifier array; the antenna, the low noise amplifier array and the liquid nitrogen refrigeration unit are arranged in the Dewar refrigeration cavity, and the antenna and the low noise amplifier array are fixed on the liquid nitrogen refrigeration unit; the micro Dewar refrigeration cavity is provided with a sealed wave-transparent window, the low noise amplifier array is connected with a heat insulation waveguide, and the heat insulation waveguide is connected to the sealed wave-transparent window and then is connected with the post-stage device. The technical scheme of the invention has the advantages of high sensitivity, high integration level, small size, light weight, low power consumption, wide application range and the like.

Description

Technical Field

[0001] The present application relates to the field of terahertz communication technology, and in particular to a terahertz refrigeration low-noise receiving front end. Background Art

[0002] Refrigeration technology is the most direct and effective way to reduce the noise temperature of the receiver and improve the receiver sensitivity. Theoretical analysis shows that for every 1-fold reduction in the noise temperature of the receiving system, the detection sensitivity of the entire system will increase by 2 times, the detection and reception data rate can be doubled, and the detection distance will increase by more than 20%. Especially in the terahertz frequency band, because the noise coefficient of the LNA device is larger, the effect of refrigeration on reducing the sensitivity of the system is more obvious. The terahertz refrigeration low-noise receiving system can realize the reception of weak terahertz electromagnetic signals and reduce the noise coefficient of the receiving front end. It has broad application prospects in anti-interference communications, space exploration, and long-distance radiometer detection systems based on brightness temperature distribution.

[0003] Traditional cooling front-ends are mainly aimed at low-frequency receiving equipment, and the cooling method mostly adopts mechanical cooling, which is large in size, heavy in weight, and high in power consumption. The atmospheric transmission loss in the terahertz frequency band is large, and long-distance transmission will cause the received signal to be very weak, so it is necessary to study high-sensitivity receiving front-ends. At the same time, for terahertz systems, they are mostly used on airborne or satellite platforms, so the requirements for indicators such as size, weight and power consumption are stringent. Summary of the invention

[0004] The embodiments of the present application provide a terahertz refrigeration low-noise receiving front end to solve the problems of low sensitivity, large refrigeration integrated volume and heavy weight of the current terahertz receiving system.

[0005] Other features and advantages of the present application will become apparent from the following detailed description, or may be learned in part by the practice of the present application.

[0006] According to a first aspect of an embodiment of the present application, a terahertz refrigeration low-noise receiving front end is provided, comprising: a micro-Dewar refrigeration cavity and a receiving front end body;

[0007] The receiving front-end body includes a front-end device and a back-end device, and the front-end device includes an antenna and a low noise amplifier array;

[0008] The antenna, the low noise amplifier array and the liquid nitrogen refrigeration unit are arranged in the Dewar refrigeration chamber, and the antenna and the low noise amplifier array are fixed on the liquid nitrogen refrigeration unit;

[0009] The micro-Dewar refrigeration cavity is provided with a sealed wave-transmitting window, the low-noise amplifier array is connected with an adiabatic waveguide, and the adiabatic waveguide is connected to the sealed wave-transmitting window and then connected to the subsequent device.

[0010] In some embodiments of the present application, based on the above solution, the micro-Dewar refrigeration chamber includes: a micro-Dewar shell and a micro-Dewar wave-transparent cover;

[0011] The sealed wave-transmitting window is arranged on the micro-Dewar housing;

[0012] The micro-Dewar wave-transparent cover is used for the antenna and the low-noise amplifier array to receive external electromagnetic signals, and is sealed and connected to the micro-Dewar housing.

[0013] In some embodiments of the present application, based on the aforementioned solution, a thermally insulated cable is provided on the micro-dewar housing for direct current power supply to the low noise amplifier array.

[0014] In some embodiments of the present application, based on the aforementioned solution, the micro-Dewar shell is made of magnesium-aluminum alloy.

[0015] In some embodiments of the present application, based on the aforementioned solution, the sealed wave-transmitting window includes: a first rectangular waveguide, a sealed dielectric sheet, a box-type structure waveguide, and a second rectangular waveguide;

[0016] The box-type structure waveguide is arranged between the first rectangular waveguide and the second rectangular waveguide;

[0017] The sealing window dielectric sheet is welded on the box-type structure waveguide.

[0018] In some embodiments of the present application, based on the above solution, the sealing window dielectric sheet is made of sapphire material.

[0019] In some embodiments of the present application, based on the aforementioned solution, the liquid nitrogen refrigeration unit includes: a nitrogen storage bottle and a liquid nitrogen pipeline;

[0020] The liquid nitrogen pipeline is connected to the nitrogen storage bottle for filling with liquid nitrogen;

[0021] The antenna and the low noise amplifier array are fixed on the nitrogen storage bottle.

[0022] In some embodiments of the present application, based on the aforementioned solution, the thermal insulation waveguide is made of a lightweight thermal insulation composite material, and a plated metal layer is provided on the surface of the thermal insulation waveguide.

[0023] In some embodiments of the present application, based on the aforementioned solution, the insulating waveguide has a flange, and the flange is embedded in the periphery of the waveguide cavity of the insulating waveguide and fixed to both ends of the waveguide cavity of the insulating waveguide by low-temperature glue.

[0024] In some embodiments of the present application, based on the aforementioned solution, the skeleton of the thermal insulation waveguide is made of a low thermal conductivity material, and the inner wall of the thermal insulation waveguide is provided with a high conductivity metal coating.

[0025] The technical solution of the present application has the advantages of high sensitivity, high integration, small size, light weight, low power consumption and wide adaptability.

[0026] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings herein are incorporated into the specification and constitute a part of the specification, showing embodiments consistent with the present application, and together with the specification, are used to explain the principles of the present application. Obviously, the drawings described below are only some embodiments of the present application, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0028] Figure 1 An exploded schematic diagram of a terahertz cooling low-noise receiving front end according to an embodiment of the present application is shown;

[0029] Figure 2 A schematic diagram of the overall structure of a terahertz cooled low-noise receiving front end according to an embodiment of the present application is shown.

[0030] Description of reference numerals:

[0031] 1-Watt wave-transparent cover, 2-antenna, 3-low noise amplifier array, 4-nitrogen storage bottle, 5-micro Dewar shell, 6-insulated waveguide, 7-post-stage components, 8-mounting frame. DETAILED DESCRIPTION

[0032] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this application will be more comprehensive and complete and fully convey the concept of the example embodiments to those skilled in the art.

[0033] In addition, described feature, structure or characteristic can be combined in one or more embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the embodiments of the present application. However, those skilled in the art will appreciate that the technical scheme of the present application can be put into practice without one or more of the specific details, or other methods, components, devices, steps, etc. can be adopted. In other cases, known methods, devices, realizations or operations are not shown or described in detail to avoid blurring the various aspects of the application.

[0034] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is only a part of the embodiment of the present invention, not all the embodiments. Based on the embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] Some embodiments of the present application will be described in detail below in conjunction with the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments may be combined with each other.

[0036] In order to solve the technical problems existing in the prior art, the present application proposes a terahertz cooled low-noise receiving front end. The present application adopts a micro-Dewar + liquid nitrogen cooling method to reduce the noise temperature of the antenna and low-noise amplifier array of the terahertz front end, and finally obtains a high-sensitivity terahertz receiving front end through the airtight and adiabatic design of the RF and DC input and output of the micro-Dewar cooling system.

[0037] Specifically, the embodiment of the present application shows a terahertz refrigeration low-noise receiving front end, including: a micro-Dewar refrigeration cavity and a receiving front end body;

[0038] The receiving front-end body includes a front-end device and a back-end device, and the front-end device includes an antenna and a low noise amplifier array;

[0039] The antenna, the low noise amplifier array and the liquid nitrogen refrigeration unit are arranged in the Dewar refrigeration chamber, and the antenna and the low noise amplifier array are fixed on the liquid nitrogen refrigeration unit;

[0040] The micro-Dewar refrigeration cavity is provided with a sealed wave-transmitting window, the low-noise amplifier array is connected with an adiabatic waveguide, and the adiabatic waveguide is connected to the sealed wave-transmitting window and then connected to the subsequent device.

[0041] It should be noted that the post-stage devices include filters, amplifiers, down-conversion mixers and local oscillator frequency multiplication devices.

[0042] It can be understood that by placing the antenna and the low noise amplifier array of the receiving front end in the micro-Dewar refrigeration chamber, the noise temperature of the front-end device can be reduced, thereby reducing the noise coefficient of the entire receiving front end.

[0043] It should be noted that the receiving front end provided in the embodiment of the present application has multi-channel receiving capability, the number of channels is 8, and it can be expanded as needed.

[0044] In some feasible embodiments, based on the above solution, the micro-Dewar refrigeration chamber includes: a micro-Dewar shell and a micro-Dewar wave-transparent cover;

[0045] The sealed wave-transmitting window is arranged on the micro-Dewar housing and is used for transmitting high-frequency radio frequency signals;

[0046] The micro-Dewar wave-transparent cover is sealed and connected to the micro-Dewar housing.

[0047] It should be noted that the micro-dewar wave-transparent cover is used for the antenna to receive external signals and seal the micro-dewar at the same time, making the micro-dewar processing and maintenance operations convenient and simple.

[0048] It can be understood that the sealed wave-transmitting window is used to provide an interface for the RF input and output waveguide ports.

[0049] In some feasible embodiments, based on the above-mentioned solution, a DC power supply interface is provided on the micro-dewar housing.

[0050] In some feasible embodiments, based on the above-mentioned solution, a thermally insulated cable is provided on the micro-dewar housing for DC power supply of the low noise amplifier array.

[0051] In some feasible embodiments, based on the above-mentioned solution, the micro-Dewar shell is made of magnesium-aluminum alloy.

[0052] It should be noted that the shell material of the micro-dewar is magnesium-aluminum alloy MB15, and a weight-reducing design with reinforcing ribs is used, which not only reduces the weight but also maintains the overall mechanical strength. The micro-dewar is connected to the main frame of the fixed front-end frequency doubling module through a TC4 titanium alloy insulation pad (mounting plate). The antenna and low-noise amplifier are installed on the end face of the cold source (nitrogen storage bottle), and the cold source and the external shell form a vacuum interlayer. The liquid nitrogen bottle can be filled with a self-pressurized liquid nitrogen tank in less than 20 minutes. After the filling is completed, the tube is removed for flexible use. The entire receiving front end realizes the integrated and integrated design of the refrigeration system and the terahertz front-end components.

[0053] In some feasible embodiments, based on the above solution, the sealed wave-transmitting window includes: a first rectangular waveguide, a sealed dielectric sheet, a box-type structure waveguide, and a second rectangular waveguide;

[0054] The box-type structure waveguide is arranged between the first rectangular waveguide and the second rectangular waveguide;

[0055] The sealing window dielectric sheet is welded on the box-type structure waveguide.

[0056] It should be noted that the first rectangular waveguide, the box-shaped structure waveguide and the second rectangular waveguide are integrally processed with the micro-Dewar housing.

[0057] It should be noted that, in the present embodiment, the overall structure of the sealed wave-transmitting window is box-shaped, and the sealed window dielectric sheet is welded to the box-shaped structure waveguide, so that it has good airtightness and can effectively prevent gas from passing through; and the box-shaped sealed wave-transmitting window, due to its advantages such as wide operating frequency band and low loss, can allow terahertz electromagnetic waves to pass through the sealed wave-transmitting window with extremely low loss.

[0058] It can be understood that, in this embodiment, one end of the adiabatic waveguide is connected to the low noise amplifier array, and the other end is connected to one end of the first rectangular waveguide, the other end of the first rectangular waveguide is connected to one end of the box-type structure waveguide, the other end of the box-type structure waveguide is connected to one end of the second rectangular waveguide, and the other end of the second rectangular waveguide is connected to the subsequent device.

[0059] In some feasible embodiments, based on the above solution, the sealing window dielectric sheet is made of sapphire material.

[0060] It should be noted that the sealing material must have good sealing performance and the ability to withstand high atmospheric pressure. If the sealing performance is poor and the vacuum degree in the micro-dewar does not meet the requirements, the heat through air convection will greatly affect the cooling of the device, resulting in a decrease in the noise performance of the system. At the same time, poor sealing will cause water accumulation on the window surface, causing the receiving device to not work properly. Therefore, a sealing window dielectric sheet made of sapphire material is selected, and the waveguide interface at both ends of the terahertz sealing window is selected as WR4.

[0061] The sealing window dielectric sheet needs to be embedded in the flange using welding technology, so a certain gap needs to be filled with solder during assembly, and it needs to work with the flange to complete the sealing and low insertion loss transmission, and electroplating is performed on the welding surface to improve the oxidation resistance of the sealing window. The high vacuum sealed wave-transparent window needs to ensure that the vacuum platform has a low leakage rate. The sealing performance of the sealed wave-transparent window needs to be tested after processing and assembly, and the vacuum degree of the sealed wave-transparent window needs to be tested using a vacuum leak detector.

[0062] Due to the difference in dielectric constant between the sealing window dielectric sheet material and air, the transmission of terahertz signals is discontinuous. In order to suppress the resonant frequency within the working frequency band, it is necessary to design an RF choke to suppress the resonance point within the band. Secondly, the resonance causes a large amount of energy to return to the feed source, causing the noise temperature of the entire receiving system to increase, thereby affecting the sensitivity of the receiving system. Therefore, it is necessary to wrap absorbing materials around the thermal isolation structure to suppress the resonant signal.

[0063] In some feasible embodiments, based on the above solution, the liquid nitrogen refrigeration unit includes: a nitrogen storage bottle and a liquid nitrogen pipeline;

[0064] The liquid nitrogen pipeline is connected to the nitrogen storage bottle;

[0065] The antenna and the low noise amplifier array are fixed on the nitrogen storage bottle.

[0066] It is understandable that a vacuum valve is provided on the liquid nitrogen pipeline. During specific use, liquid nitrogen is added through the liquid nitrogen pipeline and the vacuum valve seals the liquid nitrogen. The antenna and the low-noise amplifier array are fixed on the nitrogen storage bottle. The liquid nitrogen forms heat exchange with the antenna and the low-noise amplifier array. The small amount of volatilization of liquid nitrogen takes away the heat of the antenna and the low-noise amplifier array, thereby reducing their operating temperature.

[0067] For example, see Figure 1 , showing an exploded schematic of a terahertz-cooled low-noise receiving front end.

[0068] like Figure 1 As shown, a terahertz cooling low-noise receiving front end is shown, including a micro-dewar wave-transparent cover 1, an antenna 2, a low-noise amplifier array 3, a nitrogen storage bottle 4, a micro-dewar shell 5, an insulating waveguide 6, a post-stage device 7 and a mounting frame 8.

[0069] Among them, the micro-Dewar wave-transparent cover 1 is sealed and installed on the micro-Dewar shell 5 to form a micro-Dewar refrigeration cavity, the antenna 2, the low-noise amplifier array 3 and the nitrogen storage bottle 4 are all arranged in the micro-Dewar refrigeration cavity, and the antenna 2 and the low-noise amplifier array 3 are fixed on the nitrogen storage bottle 4, and their own working temperature is reduced by heat exchange with the nitrogen storage bottle 4; a sealed wave-transparent window is provided on the micro-Dewar shell 5, and the adiabatic waveguide 6 is connected to the low-noise amplifier array 3 in the micro-Dewar refrigeration cavity and then connected to the subsequent device 7 through the sealed wave-transparent window, and the mounting frame 8 is arranged on the periphery of the subsequent device 7. The overall structure of the receiving front end is as shown in FIG. Figure 2 shown.

[0070] It should be noted that the filter, the amplifier, the down-conversion mixer and the local oscillator frequency multiplication device are integrated in the post-stage device 7 .

[0071] In some feasible embodiments, based on the above-mentioned solution, the thermal insulation waveguide is made of a lightweight thermal insulation composite material, and a plated metal layer is provided on the surface of the thermal insulation waveguide.

[0072] It should be noted that in order to prevent external heat from being conducted into the micro-dewar through the waveguide, an adiabatic waveguide is used to make the terahertz input and output ports low-loss and thermally isolated. The adiabatic waveguide is designed by using lightweight adiabatic composite materials and surface electroplating metal to achieve the best transmission insertion loss and thermal insulation effect of electromagnetic waves.

[0073] It should be noted that the thermal insulation composite material must meet the requirement of ultra-low temperature resistance (≤77K).

[0074] In some feasible embodiments, based on the above-mentioned solution, the insulating waveguide has a flange, and the flange is embedded in the periphery of the waveguide cavity of the insulating waveguide and fixed to the two ends of the waveguide cavity of the insulating waveguide by low-temperature glue.

[0075] In some feasible embodiments, based on the above-mentioned solution, the skeleton of the thermal insulation waveguide is made of a low thermal conductivity material, and the inner wall of the thermal insulation waveguide is provided with a high conductivity metal coating.

[0076] It should be noted that the adiabatic waveguide uses low thermal conductivity materials as the skeleton of the waveguide to ensure the thermal insulation performance of the waveguide, and at the same time, a high-conductivity metal coating is integrated on the inner wall of the waveguide to ensure the transmission performance of the high-frequency RF signal of the waveguide, thereby realizing an adiabatic waveguide component with thermal insulation ability, good RF signal transmission ability, simple structure, easy assembly and low loss. The waveguide cavity can be integrated by low-temperature epoxy glass resin, and the metal coating is made of one of Au, Ag, Cu, Pd, or an alloy formed by two or more of them. Its thickness is 1 to 10μm. The flange is nested in the periphery of the waveguide cavity and fixed to both ends of the waveguide cavity by low-temperature glue.

[0077] In summary, the terahertz cooling low-noise receiving front end provided in this application has the following advantages:

[0078] High sensitivity. This application adopts a cooling method to reduce the noise coefficient of the terahertz receiving front end, and realizes high-sensitivity reception of weak terahertz electromagnetic signals transmitted over long distances. The noise coefficient of the terahertz receiving front end at room temperature can reach 7-8dBm; and the noise coefficient of the terahertz cooling low-noise receiving front end proposed in this application is estimated to be 4-5dBm.

[0079] High integration, small size, light weight, and low power consumption. This application designs a multi-channel refrigerated terahertz receiving front end with 8 channels, a channel port spacing of less than 3λ, and a volume envelope of 150mm×80mm×160mm for the entire module. The micro-Dewar + liquid nitrogen refrigeration method is adopted. Liquid nitrogen is a passive refrigeration source that does not increase the power consumption of the system. The refrigeration structure and integration method of the micro-Dewar can reduce the volume and weight of the refrigeration system.

[0080] Wide range of applications. The terahertz cooling low-noise receiving front-end design method proposed in this application has strong engineering adaptability and can be adapted to various high-sensitivity receiving occasions of terahertz signals, including terahertz long-distance communication, terahertz radiometer detection, and detection of terahertz spectrum in space.

[0081] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the embodiments disclosed herein. The present application is intended to cover any variations, uses or adaptations of the present application, which follow the general principles of the present application and include common knowledge or customary techniques in the art that are not disclosed in the present application. It should be understood that the present application is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. A terahertz cooling low noise receiving front end, characterized in that: include: Micro-Dewar refrigeration chamber and receiving front end body; The receiving front-end body includes a front-end device and a back-end device, and the front-end device includes an antenna and a low noise amplifier array; The antenna, the low noise amplifier array and the liquid nitrogen refrigeration unit are arranged in the Dewar refrigeration chamber, and the antenna and the low noise amplifier array are fixed on the liquid nitrogen refrigeration unit; The micro-Dewar refrigeration cavity is provided with a sealed wave-transmitting window, the low-noise amplifier array is connected with an adiabatic waveguide, and the adiabatic waveguide is connected to the sealed wave-transmitting window and then connected to the subsequent device.

2. The refrigerated low-noise receiving front end according to claim 1, characterized in that: The micro-Dewar refrigeration chamber comprises: a micro-Dewar shell and a micro-Dewar wave-transparent cover; The sealed wave-transmitting window is arranged on the micro-Dewar housing; The micro-Dewar wave-transparent cover is used for the antenna and the low-noise amplifier array to receive external electromagnetic signals, and is sealed and connected to the micro-Dewar housing.

3. The refrigerated low-noise receiving front end according to claim 2, characterized in that: The micro-dewar housing is provided with an insulating cable for direct current power supply to the low noise amplifier array.

4. The refrigerated low-noise receiving front end according to claim 2, characterized in that: The micro-Dewar shell is made of magnesium-aluminum alloy.

5. The refrigerated low-noise receiving front end according to claim 1, characterized in that: The sealed wave-transmitting window comprises: a first rectangular waveguide, a sealed dielectric sheet, a box-shaped structure waveguide and a second rectangular waveguide; The box-type structure waveguide is arranged between the first rectangular waveguide and the second rectangular waveguide; The sealing window dielectric sheet is welded on the box-type structure waveguide.

6. The refrigerated low-noise receiving front end according to claim 5, characterized in that: The sealing window dielectric sheet is made of sapphire material.

7. The refrigerated low-noise receiving front end according to claim 1, characterized in that: The liquid nitrogen refrigeration unit comprises: a nitrogen storage bottle and a liquid nitrogen pipeline; The liquid nitrogen pipeline is connected to the nitrogen storage bottle for filling with liquid nitrogen; The antenna and the low noise amplifier array are fixed on the nitrogen storage bottle.

8. The refrigerated low-noise receiving front end according to claim 1, characterized in that: The thermal insulation waveguide is made of a lightweight thermal insulation composite material, and a plated metal layer is arranged on the surface of the thermal insulation waveguide.

9. The refrigerated low-noise receiving front end according to claim 8, characterized in that: The thermal insulation waveguide is provided with a flange, and the flange is embedded in the periphery of the waveguide cavity of the thermal insulation waveguide and is fixed to the two ends of the waveguide cavity of the thermal insulation waveguide by low-temperature glue.

10. The refrigerated low-noise receiving front end according to claim 8, characterized in that: The framework of the thermal insulation waveguide is made of a material with low thermal conductivity, and the inner wall of the thermal insulation waveguide is provided with a high-conductivity metal coating.

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