CN114335953A - Transition structure and application thereof, and dual-mode resonant waveguide excitation method - Google Patents

Abstract

The present disclosure provides a transition structure based on a grounded coplanar waveguide-rectangular waveguide, comprising: a rectangular waveguide; a dielectric substrate on the rectangular waveguide, wherein the upper surface and the lower surface of the dielectric substrate are respectively coated with metal layers to form a grounded coplanar waveguide. The upper ground layer of the planar waveguide and the lower ground layer of the grounded coplanar waveguide, the upper ground layer of the grounded coplanar waveguide, the dielectric substrate and the lower ground layer of the grounded coplanar waveguide constitute the grounded coplanar waveguide; wherein, the lower ground layer of the grounded coplanar waveguide includes: A coupling window and a U-shaped diaphragm arranged in the coupling window, the U-shaped diaphragm is used to generate a waveguide transmission signal in a double resonance mode; the ground layer on the grounded coplanar waveguide includes: an open-circuit branch, and the open-circuit branch is used for the quasi-TEM mode Power conversion to and from TE ₁₀ modes. The present disclosure also provides a dual-mode resonant waveguide excitation method based on the transition structure of the grounded coplanar waveguide-rectangular waveguide and its application.

Description

A transition structure and its application, and a dual-mode resonant waveguide excitation method

technical field

The present disclosure relates to the technical field of terahertz systems, in particular to a transition structure and its application, and a dual-mode resonant waveguide excitation method.

Background technique

Micromechanical packaging is the best choice for the development of terahertz multi-pixel heterodyne array instruments and other advanced terahertz systems. Rectangular waveguides are considered the most suitable interface for terahertz packaging due to their advantages of excellent durability and low insertion loss. Traditional CNC metalworking can still be used for components and simple single-pixel receiver fabrication, but falls short when highly compact and integrated systems are required. Mounting circuit components vertically is a viable solution, as the LO and IF paths can be moved to the vertical dimension, allowing higher circuitry for these waveguide-based front-end receiver components such as frequency multipliers and mixers density.

In these vertically structured active and passive modules, the interconnection between the rectangular waveguide interface and the planar active circuit plays a crucial role in the transmission performance. Grounded coplanar waveguides are widely used because of their low high-frequency radiation losses in planar microwave circuits. Therefore, the vertical connection and transition from the grounded coplanar waveguide planar circuit to the rectangular waveguide stereo assembly is crucial for the entire terahertz module or system. The traditional grounded coplanar waveguide-rectangular waveguide vertical transition mainly includes probe/antenna feed, ridge waveguide transition and slot coupling. Microstrip probe excitation is currently the most commonly used transition structure, which utilizes short resonators to improve bandwidth and transition efficiency, increasing the complexity of the micro-assembly process in the terahertz band. Ridge-to-waveguide transitions employ metal ridges in the waveguide, which must fit inside the waveguide, resulting in complex fabrication and micro-assembly processes. The slot-coupling excitation method utilizes a slot in the ground to couple the electromagnetic long from the grounded coplanar waveguide to the rectangular waveguide, which results in a certain radiation loss when the excitation is used for broadband applications. Therefore, it is necessary to develop a vertical transition structure that reduces the difficulty of micro-assembly and low loss in the terahertz frequency band to achieve high-efficiency transmission of terahertz grounded coplanar waveguide planar circuits and waveguide devices.

SUMMARY OF THE INVENTION

In order to solve the above problems in the prior art, the present disclosure provides a transition structure based on a grounded coplanar waveguide-rectangular waveguide and its application, a dual-mode resonant waveguide excitation method, and the transition structure adopts a circular or fan-shaped open-circuit branch to switch the grounding Electromagnetic field between coplanar waveguide and rectangular waveguide. At the same time, the U-shaped diaphragm is embedded in the waveguide port to excite two resonance modes, which improves the transmission bandwidth. The transition structure has the advantages of high efficiency, convenient fabrication, and broadband transmission.

A first aspect of the present disclosure provides a transition structure based on a grounded coplanar waveguide and a rectangular waveguide, comprising: a rectangular waveguide; a dielectric substrate on the rectangular waveguide, wherein the upper and lower surfaces of the dielectric substrate are formed by coating metal layers respectively. The upper grounding layer of the grounded coplanar waveguide and the lower grounding layer of the grounded coplanar waveguide, the upper grounding layer of the grounded coplanar waveguide, the dielectric substrate and the lower grounding layer of the grounded coplanar waveguide constitute the grounded coplanar waveguide; wherein, the grounding layer under the grounded coplanar waveguide, It includes: a coupling window and a U-shaped diaphragm set in the coupling window, the U-shaped diaphragm is used to generate a waveguide transmission signal of double resonance mode; the ground layer on the grounded coplanar waveguide includes: an open-circuit branch, and the open-circuit branch is used for quasi-resonance mode. Power conversion between TEM mode and TE ₁₀ mode.

Further, the open branch is a circular open branch or a fan-shaped open branch.

Further, the ground layer on the grounded coplanar waveguide further includes a transmission line connected to the open-circuit branch, and the end of the transmission line is used to convert the electromagnetic wave into the main transmission mode of the rectangular waveguide through slot coupling.

Further, the size of the coupling window is the same as that of the waveguide port of the rectangular waveguide.

Further, the dielectric substrate includes: a plurality of first through holes and a second through hole, the plurality of first through holes are located on the outer side of the dielectric substrate corresponding to the waveguide ports of the rectangular waveguide, and the second through holes are located in the plurality of first through holes symmetrical position and above the center of the U-shaped diaphragm.

Further, the second through hole is a metallization matching through hole, and the metallization matching through hole is used to adjust the operating frequency of the transition structure.

Further, the frequency of the double resonance mode generated by the U-shaped diaphragm is negatively correlated with the width _wi and the length _li of the two sides of the U-shaped diaphragm.

Further, the metal layer is composed of a copper layer or a gold layer.

A second aspect of the present disclosure provides a dual-mode resonant waveguide excitation method based on the transition structure provided in the first aspect of the present disclosure, including: inputting a single-mode transmission signal on a rectangular waveguide; The shaped diaphragm is converted into a waveguide transmission signal of a dual resonance mode; the waveguide transmission signal of the dual resonance mode is output after passing through the dielectric substrate and the grounding layer on the grounded coplanar waveguide in sequence.

A third aspect of the present disclosure provides an application of the grounded coplanar waveguide-rectangular waveguide based transition structure provided in the first aspect of the present disclosure in a radio frequency front end of a terahertz wireless system.

The present disclosure provides a transition structure based on a grounded coplanar waveguide and a rectangular waveguide, an application thereof, and a dual-mode resonant waveguide excitation method. The transition structure is fed by a grounded coplanar waveguide, which not only has low-loss transmission performance, but also has broadband Features, assembly process requirements are also low. The transition structure provided by the present disclosure is suitable for broadband high-efficiency and high-integration interconnection in monolithic microwave integrated circuits, three-dimensional waveguide components, and antenna feeding applications.

Description of drawings

For a more complete understanding of the present disclosure and its advantages, reference will now be made to the following description taken in conjunction with the accompanying drawings, in which:

FIG. 1 schematically shows a perspective view of a transition structure based on a grounded coplanar waveguide-rectangular waveguide according to an embodiment of the present disclosure;

2A and 2B respectively schematically illustrate a top view of a transition structure based on a grounded coplanar waveguide and a rectangular waveguide according to an embodiment of the present disclosure;

FIG. 3 schematically shows a schematic diagram of mode conversion according to an embodiment of the present disclosure;

4A and 4B respectively schematically show a comparison diagram of simulation results of a transition structure based on a grounded coplanar waveguide and a rectangular waveguide according to an embodiment of the present disclosure;

FIG. 5 schematically shows a flowchart of a method for exciting a dual-mode resonant waveguide according to an embodiment of the present disclosure.

Detailed ways

Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. It should be understood, however, that these descriptions are exemplary only, and are not intended to limit the scope of the present disclosure. In the following detailed description, for convenience of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the present disclosure. It will be apparent, however, that one or more embodiments may be practiced without these specific details. Also, in the following description, descriptions of well-known structures and techniques are omitted to avoid unnecessarily obscuring the concepts of the present disclosure.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the present disclosure. The terms "comprising", "comprising" and the like as used herein indicate the presence of stated features, steps, operations and/or components, but do not preclude the presence or addition of one or more other features, steps, operations or components.

All terms (including technical and scientific terms) used herein have the meaning as commonly understood by one of ordinary skill in the art, unless otherwise defined. It should be noted that terms used herein should be construed to have meanings consistent with the context of the present specification and should not be construed in an idealized or overly rigid manner.

The present disclosure provides a transition structure based on a grounded coplanar waveguide and a rectangular waveguide, including: a rectangular waveguide; The upper ground layer of the planar waveguide and the lower ground layer of the grounded coplanar waveguide, the upper ground layer of the grounded coplanar waveguide, the dielectric substrate and the lower ground layer of the grounded coplanar waveguide constitute the grounded coplanar waveguide; wherein, the lower ground layer of the grounded coplanar waveguide includes: A coupling window and a U-shaped diaphragm arranged in the coupling window, the U-shaped diaphragm is used to generate a waveguide transmission signal in a double resonance mode; the ground layer on the grounded coplanar waveguide includes: an open-circuit branch, and the open-circuit branch is used for the quasi-TEM mode Power conversion to and from TE ₁₀ modes.

The transition structure provided by the embodiments of the present disclosure is fed by a grounded coplanar waveguide, which not only has low-loss transmission performance, but also has broadband characteristics and low assembly process requirements. The transition structure provided by the present disclosure is suitable for broadband high-efficiency and high-integration interconnection in monolithic microwave integrated circuits, three-dimensional waveguide components, and antenna feeding applications.

The technical solutions of the present disclosure will be described in detail below with reference to the schematic structural diagrams of the power combiner, the equivalent circuit and the power amplifier based on the slot line-grounded coplanar waveguide structure in the specific embodiments of the present disclosure. It should be understood that the transition structure based on the grounded coplanar waveguide and the rectangular waveguide, the structure of each component and the simulation results shown in FIG. 1 to FIG. 4 are only exemplary, so as to help those skilled in the art to understand the technical solutions of the present disclosure , not intended to limit the scope of protection of the present disclosure.

FIG. 1 schematically shows a perspective view of a transition structure based on a grounded coplanar waveguide-rectangular waveguide according to a first embodiment of the present disclosure.

As shown in FIG. 1 , the transition structure based on grounded coplanar waveguide and rectangular waveguide includes: rectangular waveguides 1 stacked in sequence from bottom to top and all in plate-like structure, grounded coplanar waveguide lower ground layer 2, and dielectric substrate 3 and the ground layer 4 on the grounded coplanar waveguide. Wherein, the transition structure is a left-right symmetrical structure (as shown in FIG. 1 , the transition structure is symmetrical about the x-axis).

In the embodiment of the present disclosure, the rectangular waveguide 1 may adopt a standard WR4 waveguide. The dielectric substrate 3 can be a quartz dielectric substrate with a thickness of 100 μm, and its dielectric constant is 3.82. The grounded coplanar waveguide upper grounding layer 4 and the grounded coplanar waveguide lower grounding layer 2 are respectively formed by coating the upper and lower surfaces of the dielectric substrate 3 with good conductor metal layers, wherein the grounded coplanar waveguide lower grounding layer 2 and the dielectric substrate 3 and the grounded coplanar waveguide on the ground layer 4 to form a grounded coplanar waveguide. The good conductor metal layer is a metal layer with better electrical conductivity, and preferably, the good conductor metal layer is a gold layer, a copper layer, a platinum layer, or the like.

According to the embodiment of the present disclosure, the grounding layer 2 under the grounded coplanar waveguide includes: a coupling window 21 and a U-shaped diaphragm 22 arranged in the coupling window 21, and the U-shaped diaphragm 22 is used to generate the waveguide transmission of dual resonance modes Signal. The size of the coupling window 21 is the same as the size of the waveguide port 11 of the rectangular waveguide 1 .

As shown in FIG. 2A , set the width of the U-shaped diaphragm 22 as _wi and the length of the left and right sides as _li , the dual-mode resonance frequency of the transition structure can be adjusted by adjusting the parameters _wi and _li to improve the The transition bandwidth and impedance match, and _li should be smaller than the length of the narrow side of the waveguide port 11 of the rectangular waveguide 1 to prevent the U-shaped diaphragm 22 from exceeding the range of the waveguide port 11 .

Specifically, the width _wi of the U-shaped diaphragm 22 and the length li of the narrow-walled diaphragm jointly determine the two resonant modes of the dual resonant mode _. The larger _wi is, the lower frequency resonant frequency will move to the lower frequency band , and the larger the _li is, the larger the high-frequency resonant frequency will also move to the low-frequency band. Therefore, the frequency of the double resonance mode generated by the U-shaped diaphragm 22 is negatively correlated with the width _wi and the length _li of both sides of the U-shaped diaphragm 22 .

The ground layer 4 on the grounded coplanar waveguide includes: an open branch 41 , a transmission line 42 connected to the open branch 41 , and a slot 43 located outside the open branch 41 and the transmission line 42 . Wherein, as shown in FIG. 2B , the open branch 41 is located directly above the waveguide port 11 of the rectangular waveguide 1 , and the structure formed by the two is a left-right symmetrical structure. The open stubs 41 are used for power low loss conversion between the quasi-TEM mode and the TE ₁₀ mode. The end of the transmission line 42 is used to couple and convert the electromagnetic wave into the main transmission mode of the rectangular waveguide 1 through the slot 43 .

Specifically, as shown in FIG. 2B , the open branch 41 may be a circular open branch or a fan-shaped open branch. Assuming that the distance from the center of the open branch 41 to the long side of the waveguide port 11 of the rectangular waveguide 1 is d _s , and the radius of the circular branch is _rs , the size of _rs + d _s should be smaller than the length of the narrow side of the waveguide port 11 . Preferably, the size of _rs + d _s is half of the narrow side of the waveguide port 11 , so that the electromagnetic modes of the grounded coplanar waveguides 2 , 4 are converted into the main transmission mode of the rectangular waveguide 1 .

Preferably, the longer side of the U-shaped diaphragm 22 completely coincides with the long side of the waveguide port 11 , and is symmetrically arranged with respect to the transmission line 42 of the upper grounded coplanar waveguide 4 .

In the embodiment of the present disclosure, the dielectric substrate 3 includes a plurality of first through holes 31 and second through holes 32 , and the plurality of first through holes 31 are located on the dielectric substrate 3 corresponding to the waveguide ports 11 and the transmission lines 42 of the rectangular waveguide 1 . Outside, the second through holes 32 are located at symmetrical positions of the plurality of first through holes 31 and above the central position of the U-shaped diaphragm 22 . Among them, the plurality of first through holes 31 and the second through holes 32 are all metallized through holes, and the plurality of first through holes 31 are ordinary metallized through holes, which are used to prevent electromagnetic waves from passing between the upper and lower metal surfaces of the quartz substrate 3 . A parallel-plate mode is generated between the two, resulting in energy leakage. The second through hole 32 is a metallization matching through hole, and the metallization matching through hole is used to adjust the operating frequency of the transition structure.

Further, the distance between adjacent metallized through holes should be greater than or equal to the diameter of each through hole, so as to reduce the difficulty of processing and improve the yield of manufacturing and processing.

As shown in FIG. 2B , the distance from the center of the metallized matching through hole 32 to the broad side of the waveguide port 11 is d _v , and adjusting the d _v parameter can change the operating frequency of the transition structure, so that the applicable range of the structure can be extended to any Working frequency.

As shown in FIG. 1 , the WR4 waveguide 1 is vertically terminated with the quartz substrate 3 , and the waveguide port 11 of the WR4 waveguide 1 is aligned with the upper surface of the quartz substrate 1 by etching to form a coupling window 21 .

In the embodiment of the present disclosure, the open-circuit branch 41 fed by the grounded coplanar waveguide is inserted above the center of the waveguide port 11 of the rectangular waveguide 1, and the electromagnetic wave at the end of the transmission line 42 will be converted into the main transmission mode of the rectangular waveguide 1 through slot coupling, Figure 3 shows the entire power conversion process between the quasi-TEM electromagnetic mode of the grounded coplanar waveguide and the TE ₁₀ mode of the rectangular waveguide.

As can be seen from FIG. 3 , due to the arrangement of the open-circuit branches 41 , the transition waveguide structure can well realize the quasi-TEM electromagnetic mode and the rectangular waveguide in the lower ground layer 2 of the grounded coplanar waveguide and the upper ground layer 4 of the grounded coplanar waveguide. power conversion between TE ₁₀ modes.

In theory, the diaphragm loads on the wide and narrow walls of the U-shaped diaphragm 22 are equivalent to the parallel capacitance and parallel inductance of the waveguide transmission line, respectively. The excitation structure achieves a dual-resonant transmission mode by generating two resonant frequencies associated with the U-shaped diaphragm 22, which can provide adequate capacitive and inductive compensation at low and high frequencies, respectively.

Specifically, the electric field simulation results show that the wide-walled diaphragm with capacitance in the U-shaped diaphragm 22 dominates at lower frequencies (187GHz), while the narrow-walled iris with inductance acts at higher frequencies (229GHz) main effect, resulting in a double resonance mode.

In the embodiment of the present disclosure, the transition structure is numerically placed under two conditions of using the U-shaped diaphragm 22 and not using the U-shaped diaphragm 22 , and specifically, the scattering parameters (ie, the S parameters) are simulated and calculated. 4A and 4B respectively schematically show a comparison diagram of simulation results of a transition structure based on a grounded coplanar waveguide and a rectangular waveguide according to an embodiment of the present disclosure.

As shown in Figure 4A, when the U-shaped diaphragm is not used, the transition structure only has a single resonance frequency of 210GHz, the absolute operating bandwidth is 24GHz, and the relative operating bandwidth is 11.5%. In the frequency range from 197GHz to 221GHz, the return loss S ₁₁ and return loss S ₂₂ are better than 15dB, and insertion loss S ₂₁ is lower than 0.35dB.

As shown in Figure 4B, the use of the U-shaped diaphragm can generate dual resonant modes at frequencies of 187GHz and 229GHz, and the return loss _S11 and return loss _S22 are both better than 15dB in the frequency range from 184GHz to 231GHz, and the insertion The loss S ₂₁ is lower than 0.35dB, making its absolute operating bandwidth reach 47GHz, the relative operating bandwidth is 22.7%, and the bandwidth is almost twice that without the U-shaped diaphragm. The simulation results show that the use of U-shaped diaphragm in the transition structure can effectively improve the broadband transmission performance of the transition structure.

FIG. 5 schematically shows a flowchart of a dual-mode resonant waveguide excitation method according to an embodiment of the present disclosure, where the dual-mode resonant waveguide excitation method is implemented based on the transition structure shown in FIG. 1 .

As shown in FIG. 5 , the dual-mode resonant waveguide excitation method includes: S501-S503.

S501 , a single-mode transmission signal is input on the rectangular waveguide 1 .

S502 , the single-mode transmission signal is converted into the waveguide transmission signal of the dual-resonance mode through the U-shaped diaphragm 22 .

S503 , the waveguide transmission signal of the dual resonance mode is output through the dielectric substrate 3 and the ground layer 4 on the grounded coplanar waveguide in sequence.

In some other embodiments, the single-mode transmission signal can also be input to the ground layer 4 on the grounded coplanar waveguide. The waveguide transmits the signal, and then sequentially passes through the grounding layer 2 under the grounded coplanar waveguide and the rectangular waveguide 1 and outputs it. The embodiment of the present disclosure does not limit the input direction of the input signal of the transition structure.

Another embodiment of the present disclosure provides the application of the transition structure based on the grounded coplanar waveguide to the rectangular waveguide shown in the above-mentioned embodiments in the radio frequency front-end of the terahertz wireless system. The waveguide device in the RF front end is connected to the rectangular waveguide 1 , and the planar circuit is connected to the upper grounded coplanar waveguide 4 .

In some other embodiments, the transition structure can also be used for broadband high-efficiency high-integration interconnects in monolithic microwave integrated circuits, stereoscopic waveguide components, and antenna feeding applications.

It should be noted that the above embodiments describe in detail the transition structure provided by the present disclosure, which does not constitute a limitation of the transition structure of the embodiment of the present disclosure. In other practical applications, some components in the transition structure may also be Alternatives to other structures, such as open stubs 41 include, but are not limited to, circular or fan-shaped open stubs, which may also be rectangular open stubs or open stubs of other geometric shapes.

While the present disclosure has been illustrated and described in detail in the accompanying drawings and the foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive.

Those skilled in the art will appreciate that various range combinations and/or combinations of features recited in various embodiments and/or claims of the present disclosure are possible, even if such combinations or combinations are not expressly recited in the present disclosure. In particular, various combinations and/or combinations of the features recited in the various embodiments of the present disclosure and/or in the claims may be made without departing from the spirit and teachings of the present disclosure. All such combinations and/or combinations fall within the scope of this disclosure.

Although the present disclosure has been shown and described with reference to specific exemplary embodiments of the present disclosure, those skilled in the art will appreciate that, without departing from the spirit and scope of the present disclosure as defined by the appended claims and their equivalents, Various changes in form and detail have been made in the present disclosure. Therefore, the scope of the present disclosure should not be limited to the above-described embodiments, but should be determined not only by the appended claims, but also by their equivalents.

Claims (10)

1. A transition structure based on grounded coplanar waveguide-rectangular waveguide, characterized in that, comprising: rectangular waveguide (1); A dielectric substrate (3) located on the rectangular waveguide (1), wherein metal layers are respectively coated on the upper surface and the lower surface of the dielectric substrate (3) to form a grounded coplanar waveguide upper ground layer (4) and grounding a coplanar waveguide lower ground layer (2), the grounded coplanar waveguide upper ground layer (4), the dielectric substrate (3) and the grounded coplanar waveguide lower ground layer (2) constitute a grounded coplanar waveguide; wherein , The ground layer (2) under the grounded coplanar waveguide comprises: a coupling window (21) and a U-shaped diaphragm (22) arranged in the coupling window (21), and the U-shaped diaphragm (22) is used to generate Waveguide transmission signal in double resonance mode; The ground layer (4) on the grounded coplanar waveguide includes: an open-circuit branch (41), and the open-circuit branch (41) is used for power conversion between a quasi-TEM mode and a TE ₁₀ mode. 2. The transition structure according to claim 1, characterized in that, the open-circuit branch (41) is a circular open-circuit branch or a fan-shaped open-circuit branch. 3. The transition structure according to claim 1, wherein the ground layer (4) on the grounded coplanar waveguide further comprises: A transmission line (42) connected to the open branch (41), the end of the transmission line (42) is used for coupling and converting electromagnetic waves into the main transmission mode of the rectangular waveguide (1) through the slot (43). 4. The transition structure according to claim 1, wherein the coupling window (21) has the same size as the waveguide port (11) of the rectangular waveguide (1). 5. The transition structure according to claim 1, wherein the dielectric substrate (3) comprises: a plurality of first through holes (31) and a second through hole (32), the plurality of first through holes (32) The holes (31) are located on the outer side of the dielectric substrate (3) corresponding to the waveguide openings (11) of the rectangular waveguide (1), and the second through holes (32) are located on the plurality of first through holes ( 31) and above the center of the U-shaped diaphragm (22). 6 . The transition structure according to claim 5 , wherein the second through hole ( 32 ) is a metallization matching through hole, and the metallization matching through hole is used to adjust the operating frequency of the transition structure. 7 . 7. The transition structure according to claim 1, wherein the frequency of the double resonance mode generated by the U-shaped diaphragm (22) is related to the width _wi and the length of both sides of the U-shaped diaphragm (22). l _i is negatively correlated. 8. The transition structure according to claim 1, wherein the metal layer is composed of a copper layer or a gold layer. 9 . A dual-mode resonant waveguide excitation method based on the transition structure according to any one of claims 1 to 8 , comprising: Input a single-mode transmission signal on the rectangular waveguide (1); The single-mode transmission signal is converted into a dual-resonance mode waveguide transmission signal through the U-shaped diaphragm (22); The waveguide transmission signal of the dual resonance mode is output after passing through the dielectric substrate (3) and the ground layer (4) on the grounded coplanar waveguide in sequence. 10. An application of the grounded coplanar waveguide-rectangular waveguide transition structure according to any one of claims 1 to 8 in a radio frequency front-end of a terahertz wireless system.

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