CN114335953B - A kind of transition structure and its application, double-mode resonant waveguide excitation method - Google Patents

Abstract

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

Description

A kind of transition structure and its application, double-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 to be the most suitable interface for terahertz packaging due to their excellent durability and low insertion loss. Conventional computer numerically controlled metal machining can still be used for components and simple single-pixel receiver fabrication, but falls short when highly compact and integrated systems are required. Mounting the circuit components vertically is a viable solution because 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 circuits plays a crucial role in the transmission performance. Grounded coplanar waveguides have been widely used for 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 volume component is crucial for the entire terahertz module or system. The traditional grounded coplanar waveguide-rectangular waveguide vertical transition mainly includes probe/antenna feeding, ridge waveguide transition and slot coupling. Microstrip probe excitation is currently the most commonly used transition structure, and the use of short resonant cavities to improve bandwidth and transition efficiency increases the complexity of the micro-assembly process in the terahertz band. Ridge-waveguide transitions employ metal ridges in the waveguide that must fit inside the waveguide, resulting in complex fabrication and microassembly processes. The slot-coupled excitation method uses the slot on the ground to couple the electromagnetic length from the grounded coplanar waveguide to the rectangular waveguide, which will cause certain radiation loss when the excitation is used for broadband applications. Therefore, in the terahertz frequency band, it is necessary to develop a vertical transition structure that reduces the difficulty of micro-assembly and has low loss, so as to realize the high-efficiency transmission of terahertz grounded coplanar waveguide planar circuits and waveguide devices.

Contents of the invention

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

The first aspect of the present disclosure provides a transitional structure based on grounded coplanar waveguide-rectangular waveguide, including: a rectangular waveguide; a dielectric substrate located on the rectangular waveguide, wherein the upper and lower surfaces of the dielectric substrate are coated with metal layers to form The upper ground layer of the grounded coplanar 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, Including: 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 stub, which is used for quasi- 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 stub, 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 second through holes, the plurality of first through holes are located on the outer side of the dielectric substrate corresponding to the waveguide port of the rectangular waveguide, and the second through holes are located on the outer side of the plurality of first through holes The symmetrical position and above the center position of the U-shaped diaphragm.

Further, the second through hole is a metallized matching through hole, and the metallized matching through hole is used to adjust the working 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 w _i and the lengths l _i of both sides of the U-shaped diaphragm.

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

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

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 to a radio frequency front end of a terahertz wireless system.

The disclosure provides a grounded coplanar waveguide-rectangular waveguide-based transition structure and its application, 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 characteristics, 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 should 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 schematically illustrate a top view of a grounded coplanar waveguide-rectangular waveguide-based transition structure 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 of simulation results of a transition structure based on a grounded coplanar waveguide-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 description

Hereinafter, embodiments of the present disclosure will be described with reference to the 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 purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the present disclosure. It may be evident, 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 concept of the present disclosure.

The terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting of the present disclosure. The terms "comprising", "comprising", etc. used herein indicate the presence of stated features, steps, operations and/or components, but do not exclude 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 commonly understood by one of ordinary skill in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted to have meanings consistent with the context of this specification, and should not be interpreted in an idealized or overly rigid manner.

The present disclosure provides a transition structure based on grounded coplanar waveguide-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: The coupling window and the U-shaped diaphragm set in the coupling window, the U-shaped diaphragm is used to generate the waveguide transmission signal of the double resonance mode; the ground layer on the grounded coplanar waveguide includes: open-circuit stub, the open-circuit stub is used for quasi-TEM mode Power conversion to and from TE ₁₀ mode.

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 has 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 in conjunction with the structural schematic diagrams of a power combiner based on a slot-ground coplanar waveguide structure, an equivalent circuit, and a power amplifier in a specific embodiment of the present disclosure. It should be understood that the transition structure based on grounded coplanar waveguide-rectangular waveguide, the structure of each component and the simulation results shown in FIGS. , not to limit the protection scope of the present disclosure.

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

As shown in Figure 1, the transition structure based on grounded coplanar waveguide-rectangular waveguide includes: rectangular waveguides 1 stacked in sequence from bottom to top and all in a plate-like structure, ground layer 2 under the grounded coplanar waveguide, and a dielectric substrate 3 and the ground layer 4 on the ground 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 may be a quartz dielectric substrate with a thickness of 100 μm and a dielectric constant of 3.82. The upper ground layer 4 of the grounded coplanar waveguide and the lower ground layer 2 of the grounded coplanar waveguide are respectively formed by coating the upper and lower surfaces of the dielectric substrate 3 with a good conductor metal layer, wherein the lower ground layer 2 of the grounded coplanar waveguide and the dielectric substrate 3 and the ground layer 4 on the ground coplanar waveguide form the ground coplanar waveguide. The good conductor metal layer is a metal layer with good electrical conductivity. Preferably, the good conductor metal layer is a gold layer, a copper layer, a platinum layer, or the like.

According to an embodiment of the present disclosure, the lower ground layer 2 of 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 waveguide transmission in a dual-resonant mode Signal. Wherein, the size of the coupling window 21 is the same as that of the waveguide opening 11 of the rectangular waveguide 1 .

As shown in Figure 2A, suppose the width of the U-shaped diaphragm 22 is w _i , and the length of the left and right sides is l _i , the dual-mode resonant frequency of the transition structure can be adjusted by adjusting the parameters of w _i and l _i to improve the Transition bandwidth and impedance matching, and l _i should be smaller than the length of the narrow side of the waveguide opening 11 of the rectangular waveguide 1, so as to prevent the U-shaped diaphragm 22 from exceeding the range of the waveguide opening 11.

Specifically, the width w _i of the U-shaped diaphragm 22 and the length l _i of the narrow-walled diaphragm jointly determine the two resonant modes of the double-resonant mode. The larger the _wi is, the lower the resonant frequency of the lower frequency will move to the lower frequency band , and the larger l _i is, the larger high-frequency resonance 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 w _i and the lengths l _i of both sides of the U-shaped diaphragm 22 .

The ground layer 4 on the grounded coplanar waveguide includes: an open stub 41 , a transmission line 42 connected to the open stub 41 , and a gap 43 outside the open stub 41 and the transmission line 42 . Wherein, as shown in FIG. 2B , the open branch 41 is located directly above the waveguide opening 11 of the rectangular waveguide 1 , and the structure formed by the two is left-right symmetrical. The open stub 41 is used for low-loss power 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 r _s , then the size of r _s +d _s should be smaller than the length of the narrow side of the waveguide port 11. Preferably, the size of r _s +d _s is half of the narrow side of the waveguide opening 11, so that the electromagnetic mode of the grounded coplanar waveguides 2, 4 is 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 longer side of the waveguide port 11 , and is arranged symmetrically 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 port 11 and the transmission line 42 of the rectangular waveguide 1. On the outside, the second through hole 32 is located at the symmetrical position of the plurality of first through holes 31 and above the central position of the U-shaped diaphragm 22 . Wherein, 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 them, resulting in energy leakage. The second through hole 32 is a metallized matching through hole, and the metallized matching through hole is used to adjust the working 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 processing difficulty and improve manufacturing and processing yield.

As shown in Fig. 2B, suppose the distance from the center of the metallized matching through hole 32 to the wide side of the waveguide port 11 is d _v , adjusting the d _v parameter can change the working 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 connected to the quartz substrate 3 , and the waveguide opening 11 of the WR4 waveguide 1 is aligned with the upper surface of the quartz substrate 1 to form a coupling window 21 by etching.

In the embodiment of the present disclosure, the open circuit stub 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.

It can be seen from Fig. 3 that due to the setting of the open-circuit stub 41, the transitional waveguide structure well realizes the quasi-TEM electromagnetic mode in the ground layer 2 of the ground coplanar waveguide and the ground layer 4 of the ground coplanar waveguide and the rectangular waveguide Power conversion between TE ₁₀ modes.

Theoretically, 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 sufficient 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 plays a dominant role at a lower frequency (187GHz), while the narrow-walled iris with inductance plays a leading role at a higher frequency (229GHz). main role, resulting in a double resonant mode.

In the embodiment of the present disclosure, numerical values are placed in the case of using the U-shaped diaphragm 22 and not using the U-shaped diaphragm 22 for the transition structure, and specifically the simulation calculation of the scattering parameters (ie, S parameters). 4A and 4B schematically illustrate the comparison of simulation results of transition structures based on grounded coplanar waveguide-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 210 GHz, the absolute operating bandwidth is 24 GHz, and the relative operating bandwidth is 11.5%. In the frequency range from 197 GHz to 221 GHz, the return loss S ₁₁ and return loss S ₂₂ are better than 15dB, insertion loss S ₂₁ is lower than 0.35dB.

As shown in Figure 4B, a U-shaped diaphragm can be used to generate dual resonance modes with frequencies of 187GHz and 229GHz respectively, and in the frequency range from 184GHz to 231GHz, the return loss S ₁₁ and return loss S ₂₂ are both better than 15dB, inserting 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 of when the U-shaped diaphragm is not used. The simulation calculation results show that using the U-shaped diaphragm in the transition structure can effectively improve the broadband transmission performance of the transition structure.

FIG. 5 schematically shows a flow chart of a dual-mode resonant waveguide excitation method according to an embodiment of the present disclosure. 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 , inputting a single-mode transmission signal on the rectangular waveguide 1 .

S502, the single-mode transmission signal is converted into a double-resonant mode waveguide transmission signal through the U-shaped diaphragm 22 .

S503, the waveguide transmission signal in the double resonance mode passes through the dielectric substrate 3 and the ground layer 4 on the grounded coplanar waveguide in sequence, and then outputs it.

In some other embodiments, the single-mode transmission signal can also be input into the ground layer 4 on the grounded coplanar waveguide, and the single-mode transmission signal passes through the dielectric substrate 3 and is converted into a dual-resonance mode in the U-shaped diaphragm 22 The waveguide transmits the signal, then passes through the ground layer 2 under the ground coplanar waveguide and the rectangular waveguide 1 in sequence, and then outputs it. The embodiment of the present disclosure does not limit the input direction of the transition structure input signal.

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

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

It should be noted that the above-mentioned embodiments have described the transition structure provided by the present disclosure in detail, and it 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 can also be Alternatives to other structures, for example, the open stub 41 includes, but is not limited to, a circular or fan-shaped open stub, which may also be a rectangular open stud or an open stud with other geometric shapes.

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

Those skilled in the art can understand that the features described in various embodiments and/or claims of the present disclosure can be combined and/or combined in various ranges, even if such a combination or combination is not explicitly stated in the present disclosure. In particular, without departing from the spirit and teaching of the present disclosure, the various embodiments of the present disclosure and/or the features described in the claims can be combined and/or combined in various ways. All such combinations and/or combinations fall within the scope of the present disclosure.

While the present disclosure has been shown and described with reference to certain exemplary embodiments thereto, it should be understood by those skilled in the art that other modifications may be made 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 details have been made to this 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 the equivalents of the appended claims.

Claims (7)

1. A transition structure based on grounded coplanar waveguide-rectangular waveguide, characterized in that it comprises: Rectangular waveguide (1); A dielectric substrate (3) located on the rectangular waveguide (1), wherein the upper surface and the lower surface of the dielectric substrate (3) are respectively coated with a metal layer to form a grounding layer (4) and a grounding layer (4) on the grounding coplanar waveguide The lower ground layer (2) of the coplanar waveguide, the upper ground layer (4) of the grounded coplanar waveguide, the dielectric substrate (3) and the lower ground layer (2) of the grounded coplanar waveguide constitute a grounded coplanar waveguide; wherein , The lower ground layer (2) of the ground 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 signal in double resonance mode; The dielectric substrate (3) includes: a plurality of first through holes (31) and second through holes (32), the plurality of first through holes (31) are located on the dielectric substrate (3) and the On the outside corresponding to the waveguide port (11) of the rectangular waveguide (1), the second through hole (32) is located at the symmetrical position of the plurality of first through holes (31) and the U-shaped diaphragm (22) above the center; 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 quasi-TEM mode and TE10 mode; wherein, the open circuit branch (41) is Circular open branches or fan-shaped open branches; The ground layer (4) on the ground coplanar waveguide also includes: a transmission line (42) connected to the open branch (41), and the end of the transmission line (42) is used to couple the electromagnetic wave through the slot (43) and convert it into the The main transmission mode of the rectangular waveguide (1); wherein, the longer side of the U-shaped diaphragm (22) completely coincides with the longer side of the waveguide port (11), and is about the upper grounded coplanar waveguide ( 4) The transmission lines (42) are arranged symmetrically. 2. The transition structure according to claim 1, characterized in that the coupling window (21) has the same size as the waveguide opening (11) of the rectangular waveguide (1). 3. The transition structure according to claim 1, characterized in that, the second through hole (32) is a metallized matching through hole, and the metallized matching through hole is used to adjust the working frequency of the transition structure. 4. transition structure according to claim 1, is characterized in that, the frequency of the double resonant mode that described U-shaped diaphragm (22) produces and the width w of described U-shaped diaphragm (22) and the length l of both sides _i is negatively correlated. 5. The transition structure according to claim 1, wherein the metal layer is composed of a copper layer or a gold layer. 6. A dual-mode resonant waveguide excitation method based on the transition structure according to any one of claims 1 to 5, characterized in that it comprises: Inputting a single-mode transmission signal on the rectangular waveguide (1); The single-mode transmission signal is converted into a waveguide transmission signal of a double-resonance mode through a U-shaped diaphragm (22); The waveguide transmission signal of the double resonance mode passes through the dielectric substrate (3) and the grounding layer (4) on the grounding coplanar waveguide in sequence, and then is output. 7. An application of the transition structure based on grounded coplanar waveguide-rectangular waveguide according to any one of claims 1 to 5 in a radio frequency front end of a terahertz wireless system.

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