A terahertz frequency band waveguide S-parameter transmission amplitude standard

Abstract

This solution discloses a terahertz-band waveguide S-parameter transmission amplitude standard, characterized in that it includes a waveguide plate provided with a waveguide opening, and the waveguide opening on the waveguide plate is orthogonal to the waveguide opening of the transmission system. The standard uses an attenuator that can be traced in the terahertz band as a waveguide transmission amplitude standard, and accurately calibrates the attenuation parameters of a terahertz vector network analyzer through the new attenuator. The attenuator has a simple structure, and the theoretical value of the attenuation of the attenuator in the terahertz band can be calculated using the calibration value of the physical length traceability. It can thus be used as a standard attenuator to verify the measurement capability of the transmission amplitude of the vector network analyzer, that is, it can be used as a transmission amplitude standard for the waveguide S parameters. This solution solves the problem that the coupling hole diameter of the traditional multi-hole coupling-based attenuator in the terahertz band is too small, making it difficult to process and implement.

Description

Technical Field

[0001] The present invention relates to the technical field of instrument detection, and in particular to a terahertz frequency band waveguide S-parameter transmission amplitude standard. Background Art

[0002] Vector network analyzers (VNAs) are instruments used to measure microwave networks, such as microwave amplifiers, couplers, power splitters, and isolators. They are widely used in microwave device development, manufacturing, and calibration, accurately measuring the S-parameters of the devices under test. Because VNAs have systematic errors, they must be calibrated before use. To verify the measurement accuracy of calibrated VNAs, they are tested using a series of test pieces with calibration values, such as S-parameter standards. Typically, S-parameter standards consist of a transmission amplitude standard, a transmission phase standard, and a reflection amplitude standard. Summary of the Invention

[0003] One purpose of this solution is to provide a terahertz frequency band waveguide S-parameter transmission amplitude standard. This standard has the characteristics of a simple structure. Because it is implemented using a waveguide plate that is easy to trace, it is mainly used as a transmission amplitude standard in the vector network analyzer test standard to verify the attenuation measurement capability of the network analyzer.

[0004] To achieve the above objectives, this plan is as follows:

[0005] A terahertz frequency band waveguide S-parameter transmission amplitude standard comprises a waveguide plate provided with a waveguide opening, wherein the waveguide opening on the waveguide plate is orthogonal to the waveguide opening of a transmission system.

[0006] Preferably, the transmission system is a standard rectangular waveguide determined according to the operating frequency band of the standard device.

[0007] Preferably, the waveguide opening on the waveguide plate is rectangular.

[0008] Preferably, the long side and the short side of the waveguide opening on the waveguide plate are the same length as the long side and the short side of the waveguide opening of the transmission system.

[0009] Preferably, the thickness of the waveguide plate is set according to a preset attenuation.

[0010] Preferably, when the signal frequency band transmitted by the transmission system is below 110 GHz, the long side length and short side length of the waveguide port on the waveguide plate are set according to the standard of GB11450.2-89; when the signal frequency band transmitted by the transmission system is above 110 GHz, the long side length and short side length of the waveguide port on the waveguide plate are set according to the standard of IEEE1785.1.

[0011] Preferably, the waveguide plate is further provided with screw holes and pin holes for fixing the waveguide plate to the transmission system.

[0012] Preferably, the positions of the screw holes on the waveguide plate are set according to the screw hole positions of the IEEE1785.2a waveguide flange.

[0013] Preferably, the pin holes on the waveguide plate are positioned to set the positions of the plurality of first pin holes and the plurality of second pin holes according to the pin hole positions of the IEEE1785.2a waveguide flange.

[0014] Preferably, two third pin holes are symmetrically arranged on both sides of the centers of the two narrow sides of the waveguide opening of the waveguide plate corresponding to the second pin hole.

[0015] The beneficial effects of this program are as follows:

[0016] The waveguide transmission amplitude standard designed using this solution solves the problem of traditional coupled attenuators in the terahertz band being unable to process coupling holes and guaranteeing technical specifications. The terahertz-band transmission amplitude standard designed in this solution is implemented using a simple waveguide plate, ensuring its feasibility in the terahertz band. Furthermore, the standard's simple structure facilitates length traceability and allows for the determination of its theoretical attenuation value through length calibration, making it particularly suitable for use as a transmission amplitude standard in terahertz-band S-parameter standards. The pin holes on the transmission amplitude standard designed in this solution are specially designed, allowing some transmission amplitude standards to also function as transmission phase standards. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the implementation of this solution, the following will briefly introduce the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of this solution. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0018] Figure 1 Schematic diagram of the waveguide structure. DETAILED DESCRIPTION

[0019] The following is a further detailed description of the implementation of this solution in conjunction with the accompanying drawings. Obviously, the described embodiments are only a portion of the embodiments of this solution, and are not an exhaustive list of all embodiments. It should be noted that the embodiments and features of the embodiments in this solution can be combined with each other unless they conflict.

[0020] The terms "first," "second," and the like (if any) in the specification and claims and in the accompanying drawings are used to distinguish between similar objects and are not necessarily used to describe a particular order or sequential sequence. It should be understood that the terms so used are interchangeable where appropriate so that the embodiments described herein can be implemented in sequences other than those illustrated or described herein. In addition, the terms "including" and "having," and any variations thereof, are intended to cover non-exclusive inclusions, for example, a process, method, system, product, or apparatus that includes a series of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, product, or apparatus.

[0021] It should be understood that the term "and / or" as used herein is merely a description of the relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A exists alone, A and B exist simultaneously, or B exists alone. Furthermore, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0022] Vector network analyzers are widely used in the metrology and testing of microwave devices. They can accurately measure the S parameters of the device under test. To verify the measurement accuracy of a calibrated vector network analyzer, an S-parameter standard is required to test the vector network analyzer. Typically, an S-parameter standard consists of a transmission amplitude standard, a transmission phase standard, and a reflection amplitude standard. The reflection amplitude standard is primarily implemented using a standard mismatch device and is used to verify the vector network analyzer's ability to measure reflection coefficients. The transmission amplitude standard is primarily implemented using a standard attenuator and is used to verify the vector network analyzer's ability to measure insertion loss (attenuation). The transmission phase standard is primarily implemented using an ideally matched transmission line and is used to verify the vector network analyzer's ability to measure transmission phase. In the millimeter wave and terahertz frequency bands above 50 GHz, microwave transmission lines typically use rectangular waveguide transmission lines.

[0023] Waveguide attenuators typically use attenuation plates to dissipate electromagnetic wave power, thereby creating attenuation. However, waveguide attenuators with attenuation plates inserted into the waveguide have an uneven frequency response. Furthermore, the insertion of the attenuation plates into the waveguide causes discontinuity in the dielectric within the waveguide transmission line, resulting in a significant mismatch and a relatively large voltage standing wave ratio (VSWR) (typically greater than 1.3). Furthermore, the attenuation produced by inserting the attenuation plates into the waveguide is not traceable, making it unsuitable for use as a transmission amplitude standard in S-parameter standards. In the millimeter-wave frequency band, waveguide attenuators can also be implemented as coupled attenuators. This approach uses an array of Chebyshev coupled holes to achieve a flat frequency response and a very low voltage standing wave ratio, making it suitable for use as a millimeter-wave transmission amplitude standard. However, in the terahertz frequency band, the size of the waveguide opening is further reduced, with the longest wide side extending to less than 1 mm. Fabricating a series of smaller and unequally sized holes on such a small waveguide wall is extremely challenging. Current machining precision cannot guarantee the caliber of the coupling holes, making it difficult to achieve the technical specifications of terahertz attenuators.

[0024] In order to solve the above problems, this solution provides a terahertz frequency band waveguide S parameter transmission amplitude standard, which uses orthogonally placed waveguide plates of specific thickness, and its structure is as follows: Figure 1 As shown in the figure, two key parameters are determined during the design process: the wide and narrow dimensions of the waveguide opening and the thickness of the waveguide plate. A standard rectangular waveguide corresponding to the standard's operating frequency band is selected, with the waveguide opening dimensions serving as the wide and narrow dimensions. The thickness of the waveguide plate is designed based on the required attenuation.

[0025] The attenuator designed in this scheme is realized by processing a waveguide plate of a specific thickness, placing its waveguide port orthogonally to the waveguide port of the transmission system, and controlling the wide and narrow side dimensions of the waveguide port on the waveguide plate and the thickness of the waveguide plate to realize an attenuator in the terahertz band, thereby generating attenuation and forming an attenuator. Due to the simple structure of the attenuator, the theoretical value of the attenuator attenuation in the terahertz band can be calculated using the calibration value of the physical length traceability. It can thus be used as a standard attenuator to verify the measurement capability of the transmission amplitude of the vector network analyzer, that is, as a transmission amplitude standard for the waveguide S parameters. This scheme solves the problem that the coupling hole aperture of the traditional multi-hole coupling attenuator is too small (usually the radius is on the order of tens of microns) in the terahertz band, making it difficult to process and realize. At the same time, the attenuator structure designed in this scheme can be shared with a specific transmission phase standard.

[0026] The waveguide transmission amplitude standard in this solution is made of copper with gold plating. The method for setting the position and number of holes on the waveguide plate is as follows: the wide side size of the waveguide opening is a, the narrow side size is b, and the thickness of the waveguide plate is L. The setting principles of each parameter are as follows:

[0027] 1. Set the wide side size a and narrow side size b of the waveguide port

[0028] Select the standard waveguide port wide and narrow side dimensions according to the operating frequency of the designed transmission amplitude standard. For frequency bands below 110 GHz, refer to GB11450.2-89 standard for setting; for frequency bands above 110 GHz, refer to IEEE1785.1 standard for setting;

[0029] 2. Set the screw hole position on the waveguide

[0030] To ensure the universality of the transmission amplitude standard, the screw holes on the waveguide plate adopt the positions of the screw holes on the IEEE1785.2a waveguide flange, such as Figure 1 Position A in

[0031] 3. Set the pin hole position on the waveguide

[0032] In order to ensure the universality of the transmission amplitude standard and realize the reuse with the transmission phase standard, the pin holes on the waveguide plate adopt the pin hole positions on the IEEE1785.2a waveguide flange, such as Figure 1 The positions of holes B and C in the waveguide are as follows: In order to realize the orthogonal placement of the waveguide plate, two pin holes are added on both sides of the center of the narrow side of the waveguide opening, corresponding to the inner pin hole positions, such as Figure 1 The position of D hole in the

[0033] 4. Set the thickness of the waveguide

[0034] The thickness of the waveguide is set according to the designed attenuation and operating frequency band. The higher the frequency, the smaller the waveguide thickness; the greater the attenuation, the thicker the waveguide thickness.

[0035] 5. After setting the initial value of the waveguide thickness, use electromagnetic simulation software to perform simulation optimization to determine the final result.

[0036] The process of multiplexing the terahertz frequency band S-parameter transmission amplitude standard and the transmission phase standard designed in this scheme is as follows:

[0037] Use the pin holes on the waveguide plate that are compatible with IEEE1785.2a to align the waveguide ports with the waveguides of the test system (wide side to wide side, narrow side to narrow side).

[0038] The phase value can be calculated according to the thickness of the standard using formula (1), and this value is used as its standard value.

[0039]

[0040]

[0041] In formula (1): — phase;

[0042] l—length of the standard waveguide section;

[0043] λ g —The wavelength of the electromagnetic wave propagating in the waveguide;

[0044] λ0—the wavelength of electromagnetic waves propagating in free space;

[0045] a—The broadside dimension of the standard waveguide in the design frequency band.

[0046] The following describes this solution using a specific transmission amplitude standard as an example.

[0047] Taking the 220 GHz to 330 GHz frequency band as an example, this paper details the process of fabricating a waveguide-coupled attenuator with a nominal attenuation of 20 dB using this solution. The standard waveguide for this frequency band is the WM-864, with a wide side a = 0.864 mm and a narrow side b = 0.432 mm. IEEE 1785.2a standard waveguide flanges are commonly used in this frequency band. The material used is gold-plated copper. Key design parameters include the location and number of holes in the waveguide plate, the wide side dimensions a and narrow side dimensions b of the waveguide opening, and the thickness L of the waveguide plate.

[0048] The design method of the specific standard is:

[0049] 1. Determine the wide side dimension a and narrow side dimension b of the waveguide port

[0050] Select the standard waveguide port width and narrow side dimensions according to the designed standard operating frequency.

[0051] The 220GHz~330GHz frequency band refers to the IEEE1785.1 waveguide standard to determine its waveguide broadside

[0052] a=0.864mm, narrow side b=0.432mm;

[0053] 2. Determine the location of the screw holes on the waveguide

[0054] To ensure the universality of the transmission amplitude standard, the screw holes on the waveguide plate adopt the screw hole positions on the IEEE1785.2a waveguide flange. Figure 1 The hole A position shown has a hole radius r1 = 1.78 mm;

[0055] 3. Determine the location of the pin holes on the waveguide

[0056] In order to ensure the universality of the transmission amplitude standard and realize the reuse with the transmission phase standard, the pin holes on the waveguide plate adopt the pin hole positions on the IEEE1785.2a waveguide flange. Figure 1The aperture of holes B and C shown in the figure is r2 = 0.851mm. In order to achieve the orthogonal placement of the waveguide plate, two pin holes are added on both sides of the center of the narrow side of the waveguide opening, corresponding to the inner pin hole position. Figure 1 The hole radius r3 is 0.785 mm.

[0057] 4. Determine the thickness of the waveguide

[0058] The thickness of the waveguide is calculated based on the designed attenuation and operating frequency band. The higher the frequency, the smaller the waveguide thickness, and the greater the attenuation, the thicker the waveguide. In the 220GHz to 325GHz frequency band, the center frequency attenuation is 20dB, and the estimated initial thickness is 0.3mm.

[0059] 5. After determining the initial value of the waveguide thickness, use electromagnetic simulation software to perform simulation optimization and determine the final result to be 0.28mm.

[0060] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not limitations on the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the scope of protection of the present invention.

Claims

1. A terahertz frequency band waveguide S parameter transmission amplitude standard, characterized in that: The invention comprises a waveguide plate having a waveguide opening, wherein the waveguide opening on the waveguide plate is orthogonal to the waveguide opening of the transmission system; The transmission system is a standard rectangular waveguide determined according to the working frequency band of the standard device; The waveguide opening on the waveguide plate is rectangular; The long side and the short side of the waveguide opening on the waveguide plate are the same length as the long side and the short side of the waveguide opening of the transmission system; The thickness of the waveguide plate is set according to a preset attenuation; When the signal frequency band transmitted by the transmission system is below 110 GHz, the long side length and short side length of the waveguide port on the waveguide plate are set according to the standard of GB11450.2-89; when the signal frequency band transmitted by the transmission system is above 110 GHz, the long side length and short side length of the waveguide port on the waveguide plate are set according to the standard of IEEE1785.

1.

2. The terahertz frequency band waveguide S-parameter transmission amplitude standard according to claim 1, characterized in that: The waveguide plate is also provided with screw holes and pin holes for fixing the waveguide plate to the transmission system.

3. The terahertz frequency band waveguide S-parameter transmission amplitude standard according to claim 2, characterized in that: The screw hole positions on the waveguide plate are set according to the screw hole positions of the IEEE1785.2a waveguide flange.

4. The terahertz frequency band waveguide S-parameter transmission amplitude standard according to claim 3, characterized in that: The pin holes on the waveguide plate are positioned to set the positions of the multiple first pin holes and the multiple second pin holes according to the pin hole positions of the IEEE1785.2a waveguide flange.

5. The terahertz frequency band waveguide S-parameter transmission amplitude standard according to claim 3, characterized in that: Corresponding to the second pin hole, two third pin holes are symmetrically arranged on both sides of the center of the two narrow sides of the waveguide port of the waveguide plate.

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