Non-contact terahertz waveguide switch

Abstract

The invention provides a non-contact terahertz waveguide switch, and the switch comprises a multi-path waveguide module which comprises three paths of waveguides which respectively point to three directions and are used for receiving observation signals; the receiving waveguide is used for receiving the electromagnetic waves from the multi-path waveguide module and is connected with a rear-end receiver; the linear motor is used for bearing the multi-path waveguide module and realizing switching communication between the receiving waveguide and different waveguide channels of the multi-path waveguide module through linear motion; an electromagnetic band gap structure is arranged between the receiving waveguide and the multi-path waveguide module; the electromagnetic band gap structure comprises a plurality of metal micro-columns which are arranged in a two-dimensional rectangular array mode, the metal micro-columns are fixed to the side, adjacent to the receiving waveguide, of the multi-channel waveguide module, and a set gap is formed between the metal micro-columns and the receiving waveguide. The system has the advantages that mechanical parts can be minimized, the size of the whole system is compact, and the weight and power consumption are reduced; the reliability and the service life of equipment can be improved, and the operation and maintenance cost and shutdown loss are reduced.

Description

Technical Field

[0001] This application belongs to the field of terahertz remote sensing, specifically relating to a non-contact terahertz waveguide switch. Background Technology

[0002] Terahertz waves encompass the electromagnetic spectrum from 0.1 to 10 THz. Absorption or emission spectral lines formed by the rotation of some gas molecules around their axes of symmetry fall within the microwave, millimeter-wave, and terahertz frequency bands. We can obtain relevant information about gas molecules by observing the spectral structure falling within these bands, a capability not available in the near-infrared and visible light spectra. Highly sensitive microwave radiometers are important detectors in passive remote sensing, used to acquire brightness temperature data of the atmospheres or matter of planets and their satellites, and then inverting this data to obtain various physical parameters of the target and the propagation medium. To achieve quantitative detection of observed targets and scientific applications using terahertz radiometers, and to acquire data in real-time and accurately, calibration of the radiometer is necessary. The calibration system is a crucial component of the terahertz radiometer detector, determining the detection accuracy of the radiometer system.

[0003] Radiometer calibration requires two or more calibration references (also called calibration sources) with known radiation characteristics at different temperatures. By periodically switching calibration switches, it receives radiation signals with precisely known microwave radiation characteristics (brightness temperature), thereby establishing a quantitative relationship between the radiometer's electrical signal output and the received radiation value. A common method is to place the calibration device outside the receiver (i.e., external calibration), using a mechanical rotation device to control the switching of a quasi-optical mirror, causing the receiving antenna to periodically point towards cold air and a heat source of known temperature to achieve calibration. The problem with this approach is that the calibration device occupies a significant amount of payload weight, volume, and power consumption. Especially for deep space exploration applications, which require carrying as much payload as possible, a large calibration device will limit the distance and range of deep space exploration applications.

[0004] To address the aforementioned issues, the calibration source can be integrated into the radiometer receiving system (i.e., internal calibration). This minimizes mechanical components, resulting in a more compact system with reduced weight and power consumption. Therefore, the traditional, larger rotating switching mechanism can be replaced with a waveguide switch, making the overall calibration source switching device more compact. However, waveguide switching technology remains relatively underdeveloped in the terahertz band, particularly in the submillimeter wave band above 300 GHz, where no suitable technical solutions exist.

[0005] Integrated circuit-based switching solutions have been developed for many years and are widely used, primarily in the microwave and millimeter-wave bands. The advantage of this approach is its fast switching speed, but integrated circuit-based switches suffer from high insertion loss (generally exceeding 2.5 dB) and poor isolation. High insertion loss severely degrades system noise, making it difficult to meet the performance requirements of higher frequency submillimeter-wave applications exceeding 300 GHz.

[0006] Currently, research on terahertz frequencies above 300 GHz mainly utilizes mechanical structures such as motors or microelectromechanical drivers to achieve waveguide transmission switching. In 2024, the Jet Propulsion Laboratory (JPL) in the United States developed a MEMS-based non-contact rotary single-pole double-throw waveguide switch for 500–750 GHz. The waveguide can be switched within a ±4.5° range via a rotating structure; however, due to manufacturing and design issues, the insertion loss exceeds 2.5 dB. Additionally, JPL also reported a single-pole double-throw terahertz waveguide switch driven by a linear motor. Its drawbacks include a limited number of switching channels, the use of a U-shaped waveguide switching slider, and applicability only to single-pole double-throw switching modes. Furthermore, the achievable operating frequency is relatively low, at 250–310 GHz. Summary of the Invention

[0007] The purpose of this application is to overcome the shortcomings of existing technologies, such as high insertion loss, limited number of switching channels, applicability only to single-pole double-throw switch mode, and low operating frequency.

[0008] To achieve the above objectives, this application proposes a non-contact terahertz waveguide switch, comprising: The multi-waveguide module includes three waveguides pointing in three directions for receiving observation signals. A receiving waveguide is used to receive electromagnetic waves from the multi-channel waveguide module and connect to the back-end receiver; A linear motor is used to carry a multi-channel waveguide module and achieves switching and connection between the receiving waveguide and different waveguide channels of the multi-channel waveguide module through linear motion; An electromagnetic bandgap structure is present between the receiving waveguide and the multi-channel waveguide module; The electromagnetic bandgap structure comprises several metal micropillars arranged in a two-dimensional rectangular array, fixed on the side of the multi-channel waveguide module adjacent to the receiving waveguide, and having a set gap between them.

[0009] As an improvement to the aforementioned waveguide switch, the set gap is 0~65μm.

[0010] As an improvement to the aforementioned waveguide switch, the electromagnetic bandgap structure has three waveguide ports along the direction of motion of the linear motor, corresponding to three waveguides respectively.

[0011] As an improvement to the aforementioned waveguide switch, the distance between two adjacent waveguide ports is greater than 0.886 mm, which is less than the travel range of the linear motor.

[0012] As an improvement to the aforementioned waveguide switch, the metal micropillar is a cuboid shape with a square cross-section.

[0013] As an improvement to the aforementioned waveguide switch, the width of the metal micropillar is 120 μm and the height is 117 μm; the spacing between adjacent metal micropillars is 135 μm.

[0014] As an improvement to the aforementioned waveguide switch, it also includes: The mounting base is used to support the multi-channel waveguide module, the receiving waveguide, and the linear motor, and to control the spacing between the multi-channel waveguide module and the receiving waveguide.

[0015] Compared with existing technologies, the advantages of this application are: 1. It can minimize mechanical parts, making the entire system compact, reducing weight and power consumption; 2. It can improve the reliability and service life of equipment, eliminating the need for frequent downtime to replace worn parts, extending the maintenance cycle from several months to several years, and reducing operation and maintenance costs and downtime losses; 3. It can adapt to harsh environments such as vibration and shock. In scenarios such as vehicle bumps, drone flight vibration, and spacecraft launch impact, the switching performance is stable and the signal will not be interrupted or attenuated due to the displacement of mechanical parts, making it suitable for extreme working conditions. 4. It can be integrated into a handheld terminal (weight controlled within several hundred grams), without the need for an external high-power power supply. It can work continuously for several hours on a single charge, breaking through the limitations of traditional terahertz equipment that is "bulky and dependent on mains power". This promotes the extension of terahertz technology to mobile and field applications (such as field material inspection and temporary security inspection scenarios). 5. In the space scenario, the launch cost of each 1kg payload can be as high as hundreds of thousands to millions of yuan. Lightweight design can significantly reduce launch costs; compact structure saves internal space of satellites / spacecraft and is suitable for high-density payload layout; low power consumption reduces reliance on solar panels; no metal mechanical friction parts can avoid the risk of "cold welding" in the vacuum environment, while withstanding space radiation and drastic temperature changes, improving on-orbit reliability. Attached Figure Description

[0016] Figure 1 The diagram shows a non-contact waveguide switch structure for internal calibration of a 500-600GHz radiometer. Figure 2 The image shown is a top view of a non-contact waveguide switch for internal calibration of a 500-600 GHz radiometer. Figure 3The image shows an EBG metal micropillar at the waveguide transmission interface. Figure 4 The image shows the basic structural unit of EBG; Figure 5 The image shows a single-path waveguide transmission model; Figure 6 The image shows a non-contact multi-port waveguide transmission model. Figure 7 The image shows the non-contact waveguide transmission response; Figure 8 The figure shows the response of the non-contact multiport waveguide transmission model; Figure 9 The diagram shows the distance between the receiving waveguide and the multi-channel waveguide module. Figure 10 The diagram shows the slider position between the receiving waveguide and the multi-channel waveguide module. Detailed Implementation

[0017] The technical solution of this application will be described in detail below with reference to the accompanying drawings.

[0018] like Figure 1 As shown, this application provides a non-contact terahertz waveguide switch that can be applied to the internal calibration of 500-600 GHz radiometers in deep space exploration, including: Receiving waveguide 1 is used to receive electromagnetic waves from multiplex waveguide module 2 and connect to the back-end receiver.

[0019] The multi-waveguide module 2 includes three waveguides pointing in three directions, used to connect to a horn antenna or waveguide load to receive observation signals and cold and hot calibration sources.

[0020] Linear motor 3 is used to carry the multi-channel waveguide module 2 and achieves switching and connection between different waveguide channels of receiving waveguide 1 and multi-channel waveguide module 2 through linear motion; Mounting base 4: Used to support the above components and control the spacing between non-contact waveguides.

[0021] By switching the linear motor 3, the receiving waveguide 1 and the three paths in the multi-path waveguide module 2 are respectively connected within the waveguide switch, thereby achieving switching between different paths. Since the interface flange size of the terahertz wave is larger than the waveguide opening size, the two waveguides on either side of the three paths in the multi-path waveguide module 2 are rotated in opposite directions, such as... Figure 2 As shown.

[0022] like Figure 3As shown, an electromagnetic bandgap structure 5 is constructed between the receiving waveguide 1 and the multi-channel waveguide module 2. The electromagnetic bandgap structure 5 is composed of a two-dimensional rectangular array of metal micropillars, which, through refined design, can achieve transmission and shielding in a specific frequency band. Corresponding to the three waveguides, three waveguide ports are respectively set in the horizontal direction (the direction of movement of the linear motor 3) of the electromagnetic bandgap structure 5. The multi-channel waveguide module 2 is driven by the linear motor 3, so that the positions of the three waveguide ports correspond to the waveguide ports on the receiving waveguide 1.

[0023] Waveguide transmission designs based on EBG (Electromagnetic Band Gap) structures consist of periodically arranged metal pillars, forming a two-dimensional artificial magnetic surface. The response exhibits electromagnetic bandgap characteristics, meaning there is no electromagnetic transmission within a certain frequency band. The metal pillars are cuboids with a square cross-section. The basic EBG structural unit is shown below. Figure 4 As shown, this structure, used on the inner surface of a parallel-placed, non-contact, good conductor, can form an electromagnetic shielding structure. By optimizing the design of a periodically arranged EBG structure, electromagnetic wave dissipation between gaps can be shielded, thus enabling the design of non-contact waveguide transmission structures. First, the EBG structural unit ( Figure 4 Theoretical calculations were performed to determine the spacing between EBG cells. The approximate width calculation formula for electromagnetic wave transmission is as follows:

[0024] In the formula, It is an approximate width of electromagnetic wave propagation. w It is the width of the metal micropillar. g It refers to the spacing between metal micropillars.

[0025] Assuming the width and spacing of the EBG metal columns are equal, that is We can obtain:

[0026] The cutoff frequency of the TE10 within the waveguide is:

[0027] The spacing between the metal columns can be approximated as follows:

[0028] In the formula, c It's the speed of light.

[0029] Assuming a transmission frequency of 650 GHz, the calculated width between metal pillars in the EBG structure is approximately 150 μm, which can be used as the initial design dimension. Then, through electromagnetic simulation and intrinsic modeling, the EBG structure unit dimensions within the required 400–630 GHz range can be obtained. An optimization function is established through electromagnetic simulation optimization:

[0030] The optimal values ​​for the electromagnetic bandgap structure were obtained by optimizing the width, height, and spacing of the metal pillars, where the width of the metal pillars is [value missing]. w = 120 μm, height h b =117 μm, metal column spacing g = 135μm.

[0031] Then, establish a waveguide transmission model (such as...) Figure 5 As shown), optimizing the non-contact transmission spacing can yield the optimal non-contact waveguide spacing. h g At a wavelength of 65 μm, the waveguide transmission response is relatively ideal in the 500-650 GHz range, such as... Figure 6 As shown, the distance between the top of the EBG metal pillar and the receiving waveguide is 0~65μm.

[0032] A non-contact multiport waveguide transmission model is constructed to optimize the multiport interface distribution of the waveguide switch, such as... Figure 7 As shown. Considering the travel constraints of linear motor 3, electromagnetic simulation was used to optimize the distance between the multi-ports and maximize the isolation. The results show the spacing between the waveguide ports. D p =0.866 mm, port isolation >35 dB, response as Figure 8 As shown in the figure. The simulation results show that the dimensions obtained meet the constraint of being below the motor travel distance, and the response performance meets the system requirements. In practical applications, the spacing between waveguide ports should be greater than 0.886 mm, but less than the travel range of linear motor 3 (1.5 mm).

[0033] The spacing between receiving waveguide 1 and multiplexed waveguide module 2 is determined by a slider, such as... Figure 9As shown. The slider is located on the upper and lower sides of the waveguide opening. Slots are cut on the EBG interface of the multi-channel waveguide module 2 and on the interface of the receiving waveguide 1. To minimize damage to the standard UG387 flange on the receiving waveguide side, the slot is positioned 5.05mm vertically from the waveguide opening, at the horizontal position of the pin and pin mating hole of the standard waveguide flange UG387, allowing the slider to be inserted. On the receiving waveguide side interface, a groove is cut at the same horizontal position, also located at the pin and pin mating hole of the UG387 flange. This ensures compatibility with the UG387 flange, minimizes changes to the flange structure, and facilitates independent testing and use of the receiving waveguide. In other embodiments, other forms of protrusions can be provided between the receiving waveguide 1 and the multi-channel waveguide module 2, as long as the spacing between the receiving waveguide 1 and the multi-channel waveguide module 2 meets the design requirements.

[0034] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit it. Although this application has been described in detail with reference to the embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of this application do not depart from the spirit and scope of the technical solutions of this application, and should all be covered within the scope of the claims of this application.

Claims

1. A non-contact terahertz waveguide switch, characterized in that, include: The multi-waveguide module includes three waveguides pointing in three directions for receiving observation signals. A receiving waveguide is used to receive electromagnetic waves from the multi-channel waveguide module and connect to the back-end receiver; A linear motor is used to carry a multi-channel waveguide module and achieves switching and connection between the receiving waveguide and different waveguide channels of the multi-channel waveguide module through linear motion; An electromagnetic bandgap structure is present between the receiving waveguide and the multi-channel waveguide module; The electromagnetic bandgap structure comprises several metal micropillars arranged in a two-dimensional rectangular array, fixed on the side of the multi-channel waveguide module adjacent to the receiving waveguide, and having a set gap between them.

2. The non-contact terahertz waveguide switch according to claim 1, characterized in that, The set gap is 0~65μm.

3. The non-contact terahertz waveguide switch according to claim 1, characterized in that, The electromagnetic bandgap structure has three waveguide ports along the direction of motion of the linear motor, corresponding to three waveguides respectively.

4. The non-contact terahertz waveguide switch according to claim 3, characterized in that, The distance between two adjacent waveguide ports is greater than 0.886 mm, which is less than the travel range of the linear motor.

5. The non-contact terahertz waveguide switch according to claim 1, characterized in that, The metal micropillars are cuboids with a square cross-section.

6. The non-contact terahertz waveguide switch according to claim 5, characterized in that, The width of the metal micropillar is 120 μm and the height is 117 μm; the spacing between adjacent metal micropillars is 135 μm.

7. The non-contact terahertz waveguide switch according to claim 1, characterized in that, Also includes: The mounting base is used to support the multi-channel waveguide module, the receiving waveguide, and the linear motor, and to control the spacing between the multi-channel waveguide module and the receiving waveguide.

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