Gap waveguide transmission device based on spoof surface plasmon polaritons and manufacturing method therefor

Abstract

Disclosed in the present invention are a gap waveguide transmission device based on spoof surface plasmon polaritons and a manufacturing method therefor. The device comprises two waveguide transmission structures arranged opposite each other, wherein the two waveguide transmission structures enclose a transmission channel; a gap is provided between joining surfaces of the two waveguide transmission structures; an electrically conductive layer is provided on the inner wall of the transmission channel; corrugated grooves are provided on the outer periphery of the side wall of the transmission channel where the gap is provided; the surface of each corrugated groove facing the outer side of the side wall has protrusions and recesses arranged at periodic or quasi-periodic intervals; and an electrically conductive layer is provided on the surfaces of the protrusions and recesses of the corrugated grooves, and the electrically conductive layer is electrically connected to the electrically conductive layer on the inner wall of the transmission channel. In the present invention, by means of the provision of the corrugated grooves, when there is a gap between a first waveguide transmission structure and a second waveguide transmission structure, electromagnetic energy is confined around the corrugated grooves, thereby ensuring that the electromagnetic energy can be completely transmitted in a desired direction.

Description

An artificial surface plasmon based gap waveguide transmission device and a method of manufacturing the same TECHNICAL FIELD

[0001] The present invention relates to a new type of microwave\millimeter wave device, especially suitable for microwave\millimeter wave communication, millimeter wave radar or antenna system. In particular, it relates to an artificial surface plasmon based gap waveguide transmission device and a method of manufacturing the same. BACKGROUND

[0002] In recent years, radio frequency circuits are used in products with electrical signal transmission functions, especially those involving information transmission. According to the working frequency of radio frequency, it can be divided into low frequency scenarios and high frequency scenarios. In the low frequency scenario, information propagates along the wire or cable; in the high frequency scenario, information can propagate wirelessly through radio waves or along a transmission line with low loss. Depending on the implementation function of the product, whether it is a low frequency scenario or a high frequency scenario, the transmission signal medium is required.

[0003] Previously, the products we needed in our lives had low requirements for information transmission rate, information volume, and the working frequency of information transmission was also working at low frequency, so the conventional transmission line could meet the application requirements at that time.

[0004] In recent years, with the explosive growth of data volume in smart cities, Internet of Vehicles and other new interconnection businesses, data transmission requires communication technology with transmission rate comparable to optical fiber. With the advantages of high bandwidth, high speed, high reliability, low latency, low power consumption, and large connection, it has become the product demand at this time.

[0005] To achieve high bandwidth, high reliability, low latency, low power consumption, and large connection of information transmission, the frequency to be applied must be in the high frequency (millimeter wave frequency band, THz frequency band, etc.).

[0006] In the high frequency band, common transmission lines include microstrip lines, coaxial lines, strip lines, differential lines, coplanar waveguides (CPW), dielectric integrated waveguides (SIW), and air waveguides, etc.

[0007] Microstrip lines are the most common and commonly used transmission lines, which transmit quasi-TEM waves. The structure is a strip conductor on the upper surface of the dielectric plate, and the lower surface of the dielectric plate is a metal surface. The size of the metal surface is generally consistent with the size of the dielectric, but in special cases, it may not be consistent. If this transmission line is used for high frequency transmission, the dielectric loss will seriously reduce the transmission efficiency and quality. Currently, high frequency boards with low dielectric loss at high frequencies can be used, but these boards are expensive, increasing the cost of the product. In addition, microstrip lines are exposed on the surface of the PCB, so if their length is greater than a few wavelengths, there will be additional radiation affecting the transmission efficiency and quality.

[0008] Coaxial line, also commonly used transmission line, which transmits TEM wave, its structure is composed of two coaxial cylindrical conductors, two cylindrical conductors filled with dielectric material, and microstrip line, when working at high frequency, due to the dielectric loss will seriously reduce the transmission efficiency and quality. In addition, the volume of coaxial line is large, which is not conducive to the application of small-sized products.

[0009] Strip line, commonly used microwave transmission line, which transmits TEM wave, its structure is to place a conductive strip between two ground plates. Strip line can be regarded as evolved from coaxial line, which optimizes the volume of transmission line structure (more low profile), but also due to the dielectric loss and is not suitable for high frequency.

[0010] Differential line, signal transmission has three modes: single-ended mode, common mode and differential mode, which is very suitable for high-speed transmission scenarios, but also due to the dielectric loss will reduce the transmission efficiency and transmission quality.

[0011] Coplanar waveguide, which transmits quasi-TEM wave, solves the radiation problem of microstrip line compared with microstrip line, but at high frequency, due to the existence of dielectric, the dielectric loss will also reduce the transmission efficiency and quality.

[0012] Dielectric integrated waveguide, which is derived from laminated waveguide, its structure is to add two rows of metal vias with the same radius on both sides of the double-sided copper clad dielectric plate, and the distance between adjacent two metal vias is equal. This structure, if used at high frequency, due to the dielectric loss, will also reduce the information transmission efficiency and quality.

[0013] Air waveguide, according to the structure, can be divided into: cylindrical waveguide and rectangular waveguide. Cylindrical waveguide and rectangular waveguide, which are wrapped by metal outer wall to form a closed space, the cross section is circular or rectangular, and electromagnetic wave propagates in the middle, but this structure requires very strict processing and manufacturing.

[0014] In summary, the traditional transmission line has application limitations, and when working in millimeter wave frequency band, the dielectric loss will increase rapidly, and the waveguide will also reduce the transmission efficiency and quality of electromagnetic wave due to manufacturing process problems. SUMMARY

[0015] In view of the problems existing in the above background art, the purpose of the present application is to provide a gap waveguide transmission device based on artificial surface plasmon, which is very suitable for working in millimeter wave frequency band, and other millimeter wave devices based on this technology, such as antenna.

[0016] To achieve the above technical purpose, the technical scheme adopted by the embodiments of the present application is as follows:

[0017] The gap waveguide transmission device based on artificial surface plasmons comprises two oppositely arranged waveguide transmission structures, the two waveguide transmission structures enclose a transmission channel, the waveguide transmission structure has a gap at the joint surface, the inner wall of the transmission channel has a conductive layer, the outer wall of the transmission channel with the gap is provided with a corrugated groove, the corrugated groove has a periodic or quasi-periodic interval arrangement of protrusions and grooves on the side facing the outer wall, the surface of the protrusions and grooves of the corrugated groove has a conductive layer, and the conductive layer is electrically connected to the conductive layer of the inner wall of the transmission channel.

[0018] The manufacturing method of the gap waveguide transmission device based on artificial surface plasmons comprises:

[0019] Providing two transmission structures, wherein at least one waveguide transmission structure is provided with a groove at the surface opposite to the other waveguide transmission structure, the two transmission structures have a conductive layer on the opposite surfaces, and the conductive layer covers the groove;

[0020] Forming a corrugated groove on the outer wall of the groove, the corrugated groove is fixedly electrically connected to the conductive layer of at least one of the two waveguide transmission structures; and mounting the two waveguide transmission structures so as to enclose a strip-shaped waveguide transmission channel with the conductive layer covering the groove and the conductive layer of the other waveguide transmission structure.

[0021] The gap waveguide transmission device based on artificial surface plasmons has the advantages that: 1, the assembly process and flow of the product can be simplified; 2, excellent electrical performance can be ensured within a larger assembly tolerance redundancy; 3, the simplified design and assembly process can bring low-cost advantages; and 4, the performance of the waveguide transmission is greatly improved. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to better illustrate the present application, the present application can be further illustrated by the non-limiting embodiments shown in the accompanying drawings;

[0023] Fig. 1 is a perspective view of the gap waveguide transmission device based on artificial surface plasmons according to the first embodiment of the present application;

[0024] Fig. 2 is a side view of the gap waveguide transmission device based on artificial surface plasmons according to the first embodiment of the present application;

[0025] Fig. 3 is a front view of the second metal layer of the gap waveguide transmission device based on artificial surface plasmons according to the first embodiment of the present application;

[0026] Fig. 4 is a front view of the corrugated groove for realizing artificial surface plasmons of the gap waveguide transmission device based on artificial surface plasmons according to the present application;

[0027] Fig. 5 is a schematic diagram of the equivalent model in Fig. 4 of the present application;

[0028] Figure 6 is a side view of the first metal layer and the second metal layer of the gap waveguide transmission device based on artificial surface plasmons in embodiment one of the present application;

[0029] Figure 7 is a side view of the gap waveguide transmission device based on artificial surface plasmons in embodiment two of the present application;

[0030] Figure 8 is a side view of the gap waveguide transmission device based on artificial surface plasmons in embodiment three of the present application;

[0031] Figure 9 is an exploded view of the gap waveguide transmission device based on artificial surface plasmons in embodiment four of the present application;

[0032] Figure 10 is a back view of the gap waveguide transmission device based on artificial surface plasmons in embodiment four of the present application;

[0033] Figure 11 is an insertion loss graph of the first metal layer and the second metal layer of the gap waveguide transmission device based on artificial surface plasmons in embodiment four of the present application;

[0034] Figure 12 is a perspective side view of the gap waveguide transmission device based on artificial surface plasmons in embodiment five of the present application;

[0035] Figure 13 is a cross-sectional view of the gap waveguide transmission device based on artificial surface plasmons in embodiment five of the present application;

[0036] Figure 14 is a cross-sectional view of the first metal layer and the second metal layer of the gap waveguide transmission device based on artificial surface plasmons in embodiment five of the present application;

[0037] Figure 15 is an insertion loss graph of the first metal layer and the second metal layer of the gap waveguide transmission device based on artificial surface plasmons in embodiment five of the present application. DETAILED DESCRIPTION

[0038] In order for those skilled in the art to better understand the content of the present application, the technical solutions of the present application are further described in detail below in conjunction with the drawings. It should be understood that the solutions of the present application implemented in other forms should not be limited by the embodiments described herein.

[0039] First, the artificial surface plasmon technology of the present application is described. Surface plasmon polaritons are a kind of optical frequency surface wave mode propagating along the interface between a dielectric and a metal conductor. The mode is formed by the interaction of light or other electromagnetic waves bound to the surface and the free electrons of the metal, and has the characteristics of propagating along the tangent direction of the interface and exponentially decaying in the normal direction, so it can tightly bind electromagnetic energy around the interface. Surface plasmons can generate, distribute, modulate and detect light on a subwavelength scale, and have a great driving effect on the development of photonic integrated circuit (PIC) technology. However, when the frequency is lowered to the far-infrared, terahertz and millimeter wave bands, the properties of the metal are closer to perfect electric conductors (PEC) than plasmas with negative permittivity, so they cannot support surface plasmons. To solve this problem, the present application proposes to design a special periodic or quasi-periodic structure on the outer surface of the narrow wall of the gap waveguide transmission device on both sides to realize an electromagnetic metamaterial, and then support a mode with similar characteristics to surface plasmons, namely spoof surface plasmon polaritons (SSPP).

[0040] The gap waveguide transmission device based on artificial surface plasmons of the present application comprises: two waveguide transmission structures arranged oppositely, the two waveguide transmission structures enclosing a transmission channel, the joint surface of the two waveguide transmission structures having a gap, the inner wall of the transmission channel having a conductive layer, the outer wall of the side wall of the transmission channel with the gap being provided with corrugated grooves, one side of the corrugated grooves facing the outer side of the side wall being provided with protrusions and grooves arranged at periodic or quasi-periodic intervals, the surface of the protrusions and grooves of the corrugated grooves being provided with a conductive layer, and the conductive layer being electrically connected to the conductive layer of the inner wall of the transmission channel.

[0041] Optionally, the width and interval of the grooves and protrusions of the corrugated grooves are the same, and the conductive layer on the surface of the corrugated grooves is a metal layer.

[0042] Optionally, one of the waveguide transmission structures is provided with a groove constituting the waveguide transmission channel, and the surface of the other waveguide transmission structure opposite to the groove is a smooth surface without any protrusions.

[0043] Optionally, the conductive layer provided on the waveguide transmission structure is a metal layer.

[0044] Optionally, both of the waveguide transmission structures are provided with corresponding grooves, and the opposite grooves constitute the waveguide transmission channel.

[0045] Optionally, the concave-convex direction of the corrugated groove is perpendicular to the side wall of the waveguide transmission channel.

[0046] Optionally, the corrugated groove is electrically connected with the conductive layer of the side wall of the waveguide transmission channel, and the corrugated groove and the side wall of the groove are in the same direction and have the same height.

[0047] Optionally, the width of the side wall of the groove ranges from 0.1mm to 5mm in the direction perpendicular to the waveguide transmission channel, the height ranges from 0.1mm to 5mm, the depth of the corrugated groove ranges from 0.1mm to 2mm, the width of the corrugated groove ranges from 0.1mm to 2mm, the width of the convex part between adjacent corrugated grooves ranges from 0.1mm to 2mm, and the height of the corrugated groove ranges from 0.1mm to 5mm.

[0048] Optionally, a conductor device is further arranged in the groove, the conductor device is fixedly and electrically connected with the conductive layer of at least one of the two waveguide transmission structures, and the conductor device is used to form the waveguide transmission path.

[0049] Optionally, the conductor device is a single waveguide ridge or a double waveguide ridge, one end of the waveguide ridge is used to connect the matching transition of the integrated circuit module, and the other end is also used to connect the matching transition of the integrated circuit module.

[0050] Optionally, the conductor device includes two opposite conductor devices respectively connected to the conductive layers of the two waveguide transmission structures, and the two conductor devices are in non-electrically connected state.

[0051] Optionally, the conductor device is fixedly connected to the bottom surface of the groove and is located at the central position of the bottom surface of the groove, and is symmetrically distributed along the center line in the transmission direction, or the conductor device is fixedly connected to the waveguide transmission structure without the groove and is located at the central position of the bottom surface of the groove in the vertical projection.

[0052] Optionally, at least one of the two waveguide transmission structures is further provided with a convex metal structure with the same height as the side wall of the groove, and a screw hole with the same number as the screw via holes on the other metal layer is arranged on the convex metal structure.

[0053] Optionally, the waveguide transmission structure and the conductive layer are an integral metal structure, and the corrugated groove and the surface conductive layer are an integral metal structure.

[0054] Optionally, the conductor device is a rectangular waveguide ridge, and the waveguide ridge is straight, curved or in a stepped shape.

[0055] Optionally, the corrugated groove on the two opposite side walls of the groove is in electrically connected state through the side wall of the groove and the conductive layer of one of the two waveguide transmission structures.

[0056] Optionally, one of the two waveguide transmission structures is further provided with at least one waveguide opening for radiating transmission to and receiving radiation from the waveguide transmission line.

[0057] Optionally, the protrusions and grooves of the corrugated groove are in any one of a rectangular shape, a triangular shape, a semicircular shape, a trapezoidal shape, and an elliptical shape.

[0058] The gap waveguide device of the present application comprises two metal layers arranged therebetween and two sets of periodically or quasi-periodically arranged corrugated grooves fixedly electrically connected to the metal layers of at least one waveguide transmission structure, so as to prevent wave propagation in other directions than along the intended waveguide path in the operating frequency band when there is a gap between the two waveguide transmission structures, which can be in a gapless electrically connected manner, or in a partially gapless electrically connected manner, or in a gapped non-electrically connected assembly manner.

[0059] In Embodiment One as shown in FIG. 1 and FIG. 2, a gap waveguide transmission device based on artificial surface plasmons is illustrated. Two oppositely arranged waveguide transmission structures, in this embodiment, the two waveguide transmission structures are respectively a first waveguide transmission structure 1 and a second waveguide transmission structure 2, the two waveguide transmission structures enclose a waveguide transmission channel, the joint surface of the two waveguide transmission structures has a gap gap, the inner wall of the transmission channel has a conductive layer, the side wall of the transmission channel with the gap is surrounded by a corrugated groove 7, one side of the corrugated groove 7 facing the outside of the side wall has protrusions and grooves arranged at a periodic or quasi-periodic interval, the surface of the protrusions and grooves of the corrugated groove has a conductive layer, and the conductive layer is electrically connected to the conductive layer of the inner wall of the transmission channel. The gap waveguide transmission device comprises the first waveguide transmission structure 1 and the second waveguide transmission structure 2. In this embodiment, the two waveguide transmission structures are arranged to be spaced apart by a gap gap, when gap = 0, the first waveguide transmission structure 1 and the second waveguide transmission structure 2 are in a gapless electrically connected manner; and when gap > 0, a gap is formed between the first waveguide transmission structure 1 and the second waveguide transmission structure 2. In this embodiment, the first waveguide transmission structure 1 and the second waveguide transmission structure 2 are arranged in parallel. The two waveguide transmission structures can be in a gapless electrically connected manner, or in a partially gapless electrically connected manner, or in a gapped non-electrically connected assembly manner.

[0060] The second waveguide transmission structure 2 is provided with a groove 8, wherein the bottom surface of the groove 8 is parallel to the second waveguide transmission structure 2, and the bottom surface and the side surface are provided with a conductive layer, which is a metal layer in this embodiment, and can be copper, gold, silver or the like; the two side walls 91 and 92 of the groove 8 are perpendicular or non-perpendicular to the bottom surface, and the two side walls 91 and 92 are symmetrically distributed on the two sides of the groove 8. In an embodiment, one of the waveguide transmission structures is provided with a groove constituting a waveguide transmission channel, and the surface of the other waveguide transmission structure opposite to the groove is a smooth surface without any protrusion, and preferably, the thickness is greater than 0.1 mm. The conductive layer provided on the waveguide transmission structure can also be a conductive layer of other metal layer or other material.

[0061] In another embodiment, the two waveguide transmission structures are both provided with corresponding grooves, and the corresponding grooves are oppositely arranged to constitute a strip-shaped waveguide transmission channel.

[0062] In this gap waveguide transmission device, in order to facilitate processing and manufacturing, the first waveguide transmission structure 1 serves as one of the wide sides of the waveguide channel, and the two side walls 91 and 92 of the groove 8 in the second waveguide transmission structure 2 serve as the narrow sides of the waveguide channel, and the bottom surface of the groove 8 serves as the other wide side of the waveguide channel, in other words, the first waveguide transmission structure and the second waveguide transmission structure enclose the waveguide transmission channel, wherein the bottom edge width of the groove 8 of the second waveguide transmission structure is greater than the height of the side wall. Thus, the groove 8 of the second waveguide transmission structure 2 and the first waveguide transmission structure 1 form a waveguide transmission channel for transmitting electromagnetic energy.

[0063] As shown in FIG. 1, the upper and lower surfaces of the first waveguide transmission structure 1 in the first embodiment of the present application are smooth metal surfaces without any protrusion, and the material can be copper punched, CNC or plastic formed surface degree metal. In addition, in order to ensure the structural strength and flatness, the thickness can be set to be greater than 0.1 mm. In other embodiments, the surface of the first waveguide transmission structure 1 opposite to the groove can also be provided with a corresponding groove. In other embodiments, the first waveguide transmission structure can also be of other insulating materials, and a conductive layer or a metallized layer is formed on the surface.

[0064] In order to better electrically connect the first waveguide transmission structure 1 and the second waveguide transmission structure 2, a plurality of screw through holes 4 are provided on the first waveguide transmission structure 1 in the first embodiment, as shown in FIG. 1, the screw through holes 4 on the first waveguide transmission structure 1 are arranged on the two sides of the waveguide transmission channel, and the screw through holes 4 on the two sides of the waveguide transmission channel can be equal in number or unequal in number, and can be symmetric about the waveguide transmission channel or can not be symmetric about the waveguide transmission channel. It should be noted that, in order to ensure better electrical connection between the first waveguide transmission structure 1 and the second waveguide transmission structure 2, the screw through holes 4 should be at least four, and should be respectively arranged in the four corners of the first waveguide transmission structure 1.

[0065] In addition to fixing the first waveguide transmission structure 1 and the second waveguide transmission structure 2 by screwing, as mentioned above, the first waveguide transmission structure 1 and the second waveguide transmission structure 2 can also be fixed by riveting or welding.

[0066] In one embodiment, stepped metal protrusions can be provided to better accommodate screw through holes. Referring to Figures 1 and 2, a first step 111 and a second step 112 are also provided on the front side of the second waveguide transmission structure 2, and screw holes 5 are provided on the first step 111 and the second step 112. The position and number of screw holes 5 correspond one-to-one with the position and number of screw through holes on the first waveguide transmission structure 1. This allows the first waveguide transmission structure 1 and the second waveguide transmission structure 2 to be better fixed together by screws 3.

[0067] In addition, to reduce the overall weight of the product, a groove 101 can be reserved between step 111 and side wall 91, and a groove 102 can be reserved between step 112 and side wall 92.

[0068] As shown in Figures 1 and 2, periodic or quasi-periodic corrugated grooves 7 are further provided on the outer sides of the waveguide transmission channel sidewall 91 and the waveguide transmission channel sidewall 92 on both sides of the groove 8. These corrugated grooves 7 are fixedly connected to the second waveguide transmission structure 2, thereby forming artificial surface plasmons to block the propagation of electromagnetic waves in the operating frequency band in directions other than the intended electromagnetic transmission path. All corrugated grooves 7 are electrically connected to each other at their bases at least via the waveguide transmission structure to which they are fixedly connected. Some of the corrugated grooves 7 are electrically connected to the first waveguide transmission structure 1, while others are not electrically connected to the first waveguide transmission structure 1. In this embodiment, the concave-convex direction of the corrugated grooves is perpendicular to the sidewall of the groove 8, and the corrugated grooves 7 are arranged periodically or quasi-periodically along the groove 8. In one embodiment, the width and spacing of the grooves and protrusions of the corrugated grooves are the same, and the conductive layer on the surface of the corrugated grooves is a metal layer. In one embodiment, the corrugated groove is electrically connected to the conductive layer of the waveguide transmission channel sidewall, and the corrugated groove and the groove sidewall are at the same height in the same direction.

[0069] To facilitate installation and better constrain signal transmission, the height of the corrugated groove 7 can be set to be higher than, equal to or lower than the waveguide transmission channel sidewall 91 and the waveguide channel sidewall 92. In addition, the waveguide channel sidewall 91 and the waveguide channel sidewall 92 are at the same height, and their height can be equal to or lower than the step 111 and the step 112, wherein the step 111 and the step 112 are at the same height.

[0070] The gap waveguide transmission device described in Embodiment 1 further includes at least one conductor device in the second waveguide transmission structure 2. The conductor device is fixedly electrically connected to the second waveguide transmission structure 2 and is not electrically connected to the first waveguide transmission structure 1. The conductor device thus forms the waveguide transmission path, making the bandwidth of the transmitted signal more flexible.

[0071] The described conductor device is a single waveguide ridge or two waveguide ridges. Its width and height are set between 0.1mm and 2mm. Furthermore, the waveguide ridge can be straight, curved, or other irregular shapes.

[0072] The rectangular waveguide ridge 6 described in this invention has one end used for connecting the matching transition of an integrated circuit module, and the other end can also be used for connecting the matching transition of an integrated circuit module.

[0073] The aforementioned conductor device, namely the waveguide ridge 8, is typically set with a width between 0.1mm and 2mm and a height between 0.1mm and 2mm in order to better operate in the millimeter-wave frequency band.

[0074] As shown in Figures 3 and 4, in Embodiment 1, the corrugated groove 7 has the following characteristics: the spacing p between adjacent corrugated grooves 7 is set in the range of 0.5mm-5mm; the depth h of the corrugated groove 7 is set in the range of 0.1mm-2mm; the width d of the corrugated groove 7 is set in the range of 0.1mm-2mm; the width of the protrusion in the middle of adjacent corrugated grooves 7 is set in the range of 0.1mm-2mm; and the height of the corrugated groove, that is, the height perpendicular to the second waveguide transmission structure, is set in the range of 0.1mm-5mm.

[0075] The shape of the corrugated groove can be rectangular, triangular, semi-circular, trapezoidal, elliptical, or other irregular shapes.

[0076] The width of the waveguide transmission channel sidewall 91 and sidewall 92, which are perpendicular to the electromagnetic transmission direction, is set between 0.4 mm and 1 mm.

[0077] The first waveguide transmission structure 1 and the second waveguide transmission structure 2 can be fully electrically connected, partially electrically connected, or completely non-electrically connected in the projection area of ​​the corrugated groove 7 and the groove 8.

[0078] The corrugated groove 7 of the present invention is electrically connected to adjacent corrugated grooves 7 via the waveguide transmission channel sidewall 91 and the waveguide transmission channel sidewall 92 of the groove 8 and the second waveguide transmission structure 2. This waveguide transmission channel is suitable for transmitting microwaves, millimeter waves, terahertz waves, etc., with operating frequencies exceeding 1 GHz.

[0079] Referring to Figure 4, which is a top view of the outer corrugated groove of a narrow wall of groove 8, each corrugated groove has a width of d, a depth of h, and a spacing of p between adjacent grooves.

[0080] Referring to Figure 6, there is a gap between the first waveguide transmission structure 1 and the second waveguide transmission structure 2. This gap is inevitable during actual product assembly, especially when the first and second waveguide transmission structures are fixed with screws. The presence of this gap leads to electromagnetic energy leakage. The focus of this invention is to prevent electromagnetic energy leakage using artificial surface plasmon resonance technology. For example, when there is a gap between the first and second waveguide transmission structures, the energy is confined by the corrugated grooves of the electrical connection on the outer sidewall of the waveguide channel, causing the electromagnetic energy to propagate along the desired transmission path. Furthermore, the electromagnetic energy attenuates rapidly in the direction perpendicular to the transmission path, thus ensuring complete transmission of the electromagnetic energy to the designated direction.

[0081] Figure 7 shows a second embodiment where the waveguide ridge 6 is not loaded inside the groove 8. Its working principle is the same as that of the first embodiment. When there is no gap between the first waveguide transmission structure 1 and the second waveguide transmission structure 2, it can be considered as a conventional rectangular air waveguide. However, when there is a gap between the first waveguide transmission structure 1 and the second waveguide transmission structure 2, the artificial surface plasmons will be excited, which will confine the electromagnetic energy around the corrugated groove and propagate along the desired electromagnetic transmission direction.

[0082] Figure 8 illustrates Embodiment 3 of the present invention. While a waveguide ridge 6 is loaded inside the groove 8, waveguide ridges (not shown) are also provided on the surfaces opposite to the first waveguide transmission structure 1 and the second waveguide transmission structure 2. The waveguide ridge on the first waveguide transmission structure 1 and the waveguide ridge 6 inside the groove 8 are not electrically connected. Furthermore, the working principle of Embodiment 3 is the same as that of Embodiments 1 and 2. When there is no gap between the first waveguide transmission structure 1 and the second waveguide transmission structure 2, it can be considered a conventional double-ridge rectangular waveguide. However, when there is a gap between the first waveguide transmission structure 1 and the second waveguide transmission structure 2, the excitation of artificial surface plasmons will confine the electromagnetic energy around the corrugated groove and propagate along the desired electromagnetic transmission direction.

[0083] Figures 9 and 10 are front and back views of Embodiment 4 of the present invention. Compared to the previous three embodiments, Embodiment 4 connects a vertical waveguide 14 at the beginning and a vertical waveguide 15 at the end of the gap waveguide transmission device. To achieve impedance matching, a matching stub 12 is provided at the junction of the groove 8 and the vertical waveguide 14, and a matching stub 13 is provided at the junction of the groove 8 and the vertical waveguide 15. To prevent gaps between the first waveguide transmission structure 1 and the second waveguide transmission structure 2 during product assembly, this embodiment provides a periodic or quasi-periodic corrugated groove around the outer sidewalls 91 and 92 of the groove 8. Thus, when gaps exist between the first waveguide transmission structure 1 and the second waveguide transmission structure 2, the corrugated groove realizes the function of artificial surface plasmon resonance, confining electromagnetic energy and causing the electromagnetic energy to propagate in the desired direction.

[0084] In another embodiment, the waveguide transmission structure can be made of metal or other conductive materials, or it can be made of other materials and a conductive layer is formed on the surface by metallization. The present invention does not limit the thickness of the surface conductive layer or the metal layer, as long as it includes a metal layer for waveguide transmission, it is within the protection scope of the present invention.

[0085] Transmission lines, as the most basic components of microwave circuits, are indispensable in microwave / millimeter-wave applications. However, with the increasing demands for functional diversity in modern information technology, the shortcomings of traditional microstrip lines and coplanar waveguides in terms of electromagnetic modes and performance are becoming increasingly apparent. To address this issue, artificial surface plasmon transmission lines have been designed based on microstrip lines. However, these are typically microstrip lines on printed circuit boards (PCBs). As the application frequency increases, the dielectric loss of these microstrip lines increases significantly. Furthermore, for multi-channel transmission lines, their layout is limited by the constraints of designing them on a single plane. Therefore, with the increase in operating frequency, air waveguide transmission lines have become a popular application. They not only effectively solve the loss problem but also can be used in multi-channel designs. However, traditional air waveguide transmission lines present assembly challenges. At high frequencies, any gaps between traditional air waveguide transmission lines can lead to electromagnetic energy leakage, thus affecting signal transmission quality. Therefore, in light of the above issues, this paper proposes a waveguide transmission device based on artificial surface plasmons, designed on the basis of air waveguides. Its working principle is as follows: by loading periodic or non-periodic corrugated groove structures on the outer sides of the two narrow walls or two wide sides of the traditional air waveguide, when there is a gap between the first waveguide transmission structure and the second waveguide transmission structure, the existing corrugated grooves can tightly bind the electromagnetic energy within the air waveguide transmission channel, thereby greatly reducing the assembly process difficulty while ensuring performance.

[0086] Based on the operating frequency requirements, the relevant dimensions of the corrugated grooves of the artificial surface plasmon can be calculated according to the following theory. Assuming an infinitely long ideal metallic conductor is simulated in the transverse direction of the transmission line, and its boundary conditions in the ±y directions are set as ideal magnetic walls, the model of this transmission channel can then be equivalent to a dielectric plate of thickness h, located above the ideal conductor, exhibiting uniform but anisotropic behavior, as shown in Figure 5. Its relevant parameters are as follows:

[0087] When electromagnetic waves propagate at the speed of light in the y or z direction, the following relationship can be obtained.

[0088] The dispersion curve of the ideal metal structure SSPP transmission line unit can be obtained using the above relationship, thereby obtaining the relevant parameters of the required corrugated groove, such as the width d of the corrugated groove, the depth h of the corrugated groove, and the spacing p between adjacent corrugated grooves.

[0089] In the above formula, ε x , ε y , ε z Let μ be the relative permittivity in the x, y, and z directions of the anisotropic dielectric substrate. y and μ z Let k be the permeability in the y and z directions of the anisotropic dielectric plate. x Let be the wave number of the anisotropic dielectric plate in one period in the x-direction, and k0 be the wave number in one period in free space.

[0090] When a gap exists between the first and second waveguide transmission structures, surface plasmon polaritons are excited at the metal-dielectric interface. This surface wave reduces the transmission energy of electromagnetic energy in the desired direction. This invention simulates and modulates the characteristics of this surface wave by setting periodic or non-periodic artificial structures, i.e., corrugated grooves, on the outer side of the side walls of the groove.

[0091] When electromagnetic waves irradiate an artificial periodic structure, the structure's periodicity and specific geometry induce localized enhancement and resonance of the electromagnetic field. This resonance causes the electromagnetic field to interact with the artificial structure, thereby exciting surface plasmons. This further causes the leaked electromagnetic waves to attenuate rapidly along the n-direction and propagate along the t-direction (the desired electromagnetic transmission direction). Thus, when a gap exists between the first and second waveguide transmission structures, the artificial periodic structure can confine the electromagnetic energy within the transmission channel, allowing the electromagnetic waves to propagate losslessly along the desired direction.

[0092] The parameter design method for the corrugated groove has been given above. The theoretical parameters are derived based on the actual operating frequency, and then optimized by combining electromagnetic simulation software to obtain the optimal size and minimum transmission loss.

[0093] In one embodiment, the other end of the vertical waveguide 14 is the first waveguide port 16, and the other end of the vertical waveguide 15 is the second waveguide port 17. In order to prevent energy leakage caused by gaps in the connection between the wave gap waveguide transmission device and other structures, as shown in Figure 10, this embodiment four sets up periodic or quasi-periodic corrugated grooves around the first waveguide port 16 and the second waveguide port 17. Their function is also to prevent energy leakage caused by gaps.

[0094] Figure 11 shows the simulated insertion loss curves for the fourth embodiment of the present invention. As can be seen from the figure, when there is no gap between the first waveguide transmission structure 1 and the second waveguide transmission structure 2, the insertion loss is 0.095 dB / 25 mm within the operating frequency band (all embodiments of the present invention use 76-81 GHz as a reference design). When there is a gap between the first waveguide transmission structure 1 and the second waveguide transmission structure 2, and an artificial surface plasmon resonance (ASPR) structure is arranged around the gapped waveguide transmission device, the insertion loss within the operating frequency band is 0.115 dB / 25 mm. When there is no ASPR structure around the gapped waveguide transmission device, and there is a gap between the first waveguide transmission structure 1 and the second waveguide transmission structure 2, the insertion loss within the operating frequency band is 1 dB / 25 mm. Therefore, it can be concluded that the design of ASPR can greatly improve the electromagnetic energy leakage problem caused by the gap between the first waveguide transmission structure 1 and the second waveguide transmission structure 2.

[0095] Figure 12 is a structural schematic diagram of Embodiment 5 of the present invention. In this embodiment, the first sidewall 91 and the second sidewall 92 of the waveguide channel are the wide sides of the gap waveguide transmission device, and the depth of the metal groove is greater than its width. This is different from the previous four embodiments, in which the first sidewall 91 and the second sidewall 92 of the waveguide channel are the narrow sides of the gap waveguide transmission device. Figure 12 shows a cross-sectional schematic diagram of Embodiment 5 and illustrates the current distribution at the waveguide port. Figure 13 shows the case where the first waveguide transmission structure 1 and the second waveguide transmission structure 2 in Embodiment 5 have a gap, and also shows the current distribution at the waveguide port.

[0096] In Embodiment 5, an artificial surface plasmon structure is also provided on the outer side wall of the waveguide channel. The purpose is to prevent electromagnetic energy leakage when there is a gap between the first waveguide transmission structure 1 and the second waveguide transmission structure 2, and to transmit electromagnetic energy along the desired transmission path.

[0097] Figure 15 shows the insertion loss of the gapped waveguide transmission device in Embodiment 5. As can be seen from the figure, when there is no gap between the first waveguide transmission structure 1 and the second waveguide transmission structure 2, the insertion loss is 0.08 dB / 25 mm within the operating frequency band (all embodiments of this invention are designed with 76-81 GHz as a reference). When there is a gap between the first waveguide transmission structure 1 and the second waveguide transmission structure 2, and an artificial surface plasmon resonance (ASPR) structure is provided around the gapped waveguide transmission device, the insertion loss is 0.10 dB / 25 mm within the operating frequency band. When there is no ASPR structure around the gapped waveguide transmission device, and there is a gap between the first waveguide transmission structure 1 and the second waveguide transmission structure 2, the insertion loss is 1 dB / 25 mm within the operating frequency band. Therefore, it can be concluded that the design of ASPR can greatly improve the electromagnetic energy leakage problem caused by the gap between the first waveguide transmission structure 1 and the second waveguide transmission structure 2.

[0098] The present invention also provides a method for manufacturing a gap waveguide transmission device, comprising:

[0099] Two transmission structures are provided, wherein at least one waveguide transmission structure has a groove on the surface opposite to the other waveguide transmission structure, and a conductive layer is provided on the opposite surfaces of the two transmission structures, the conductive layer covering the groove.

[0100] A corrugated groove is formed on the outer wall of the groove, and the corrugated groove is fixedly electrically connected to the conductive layer of at least one of the two waveguide transmission structures. The two waveguide transmission structures are installed so that the conductive layer covering the groove and the conductive layer of the other waveguide transmission structure form a strip-shaped waveguide transmission channel. In all the above embodiments, the periodic or quasi-periodic corrugated grooves can be manufactured by milling or etching. The first waveguide transmission structure 1, which does not contain a periodic or quasi-periodic metal layer, can be stamped from brass, CNC machined, or gold-plated on a plastic surface. The second waveguide transmission structure 2 can be realized by CNC machining or plastic electroplating.

[0101] The corrugated grooves electrically connected to the outer side walls of the grooves in the waveguide device of the present invention can prevent wave propagation in the operating frequency band in directions other than along the intended waveguide path.

[0102] The periodic or quasi-periodic corrugated grooves can be manufactured by milling, etching, injection molding followed by gold plating, or other micro-forming techniques.

[0103] The metal layer that does not contain periodic or quasi-periodic corrugated grooves can be made by stamping brass, CNC manufacturing, gold plating on the surface after plastic injection molding, metal plating on the surface of PCB board, or other materials with good electrical conductivity.

[0104] The metal plated on it can be part or all of the metal layer. In addition, the metal plated is usually copper, silver, gold and other metals.

[0105] The two waveguide transmission structures are electrically connected without gaps by means of screw fastening, welding or riveting. Alternatively, a combination of screw fastening, welding or riveting can be used to achieve a non-electrical connection with gaps between the two waveguide transmission structures.

[0106] The metal layer containing periodic or quasi-periodic corrugated grooves can be manufactured by CNC machining, PCB surface metallization, electroplating after injection molding, or other materials with good electrical conductivity.

[0107] This invention involves etching periodic or quasi-periodic corrugated grooves on the sidewalls of a conventional rectangular waveguide away from the waveguide channel. By designing appropriately sized corrugated grooves based on the operating frequency, electromagnetic energy can be confined around the corrugated grooves even when there is a gap between the first and second waveguide transmission structures. Furthermore, the electromagnetic energy rapidly attenuates in the direction perpendicular to the desired transmission direction, ensuring that the electromagnetic energy is transmitted entirely along the desired path. This technique is called artificial surface plasmon resonance. Firstly, this technology supports conventional welding processes but does not require the high precision of conventional welding. The technology of this invention is not demanding in terms of welding precision while ensuring good electrical performance. Secondly, this technology can also eliminate the need for welding, allowing assembly directly through screws, riveting, or other fixing methods, while still maintaining good electrical performance. This new technology significantly increases the assembly tolerance redundancy of products, thereby improving the assembly yield of production lines, greatly reducing costs, and offering excellent electrical performance, making it highly suitable for millimeter-wave frequency applications.

[0108] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A gap waveguide transmission device based on artificial surface plasmons, characterized in that, include: Two waveguide transmission structures are arranged opposite each other, forming a transmission channel. The two waveguide transmission structures have a gap at their joint surface. A conductive layer is provided on the inner wall of the transmission channel. A corrugated groove is provided on the outer periphery of the side wall of the transmission channel with the gap. The side of the corrugated groove facing the outer side wall has periodically or quasi-periodically spaced protrusions and grooves. The surface of the protrusions and grooves of the corrugated groove has a conductive layer, which is electrically connected to the conductive layer on the inner wall of the transmission channel.

2. The gap waveguide transmission device according to claim 1, characterized in that, The corrugated grooves have the same width and spacing as the protrusions, and the conductive layer on the surface of the corrugated grooves is a metal layer.

3. The gap waveguide transmission device according to claim 1, characterized in that, One of the waveguide transmission structures has a groove forming a waveguide transmission channel, while the other waveguide transmission structure has a smooth surface without any protrusions on the surface opposite the groove.

4. The gap waveguide transmission device according to claim 1, characterized in that, The conductive layer on the waveguide transmission structure is a metal layer.

5. The gap waveguide transmission device according to claim 1, characterized in that, Both waveguide transmission structures are provided with corresponding grooves, and the corresponding grooves of the two waveguide transmission structures form a waveguide transmission channel.

6. The gap waveguide transmission device according to claim 1, characterized in that, The concave-convex direction of the corrugated groove is perpendicular to the sidewall of the waveguide transmission channel groove.

7. The gap waveguide transmission device according to claim 3 or 5, characterized in that, The corrugated groove is electrically connected to the conductive layer of the sidewall of the waveguide transmission channel, and the height of the corrugated groove and the sidewall of the groove are in the same direction and are the same as the height of the sidewall of the groove.

8. The gap waveguide transmission device according to claim 6, characterized in that, The width of the sidewall of the groove along the direction perpendicular to the waveguide transmission channel is between 0.1mm and 5mm, and the height is between 0.1mm and 5mm. The depth of the corrugated groove is set between 0.1mm and 2mm. The width of the corrugated groove is set between 0.1mm and 2mm. The width of the raised portion between adjacent corrugated grooves is set between 0.1mm and 2mm. The height of the corrugated groove is between 0.1mm and 5mm.

9. The gap waveguide transmission device according to claim 1, characterized in that, A conductor device is also provided in the groove, which is fixedly electrically connected to the conductive layer of at least one of the two waveguide transmission structures, and the conductor device is used to form the waveguide transmission path.

10. The gap waveguide transmission device according to claim 8, characterized in that, The conductor device is a single waveguide ridge or two waveguide ridges. One end of the waveguide ridge is used to connect the matching transition of the integrated circuit module, and the other end is also used to connect the matching transition of the integrated circuit module.

11. The gap waveguide transmission device according to claim 9, characterized in that, The conductor device includes two opposing conductor devices that are respectively connected to the conductive layers of two waveguide transmission structures, and the two conductor devices are in a non-electrical connection.

12. The gap waveguide transmission device according to claim 9, characterized in that, The conductor device is fixedly connected to the bottom surface of the groove and located at the center of the bottom surface of the groove, symmetrically distributed along the center line of the transmission direction, or the conductor device is fixedly connected to a waveguide transmission structure without a groove and projected along the direction perpendicular to the bottom surface of the groove, with the conductor device located at the middle position of the bottom surface of the groove.

13. The gap waveguide transmission device according to claim 1, characterized in that, At least one of the two waveguide transmission structures is further provided with a raised metal structure at the same height as the sidewall of the groove, and the raised metal structure is provided with screw holes with the same number of screw through holes as the other metal layer.

14. The gapped waveguide transmission device according to claim 1, characterized in that, The waveguide transmission structure and the conductive layer are integrated into a metal structure, and the corrugated groove and its surface conductive layer are an integral metal structure.

15. The gap waveguide transmission device according to claim 9, characterized in that, The conductor device is a rectangular waveguide ridge, and the waveguide ridge can be straight, curved, or stepped.

16. The gap waveguide transmission device according to claim 1, characterized in that, The corrugated grooves located on the two opposite sidewalls of the groove are electrically connected through the sidewalls of the groove and the conductive layer of one of the two waveguide transmission structures.

17. The gap waveguide transmission device according to claim 1, characterized in that, One of the two waveguide transmission structures is further provided with at least one waveguide opening, which is used for radiating transmission to and from the waveguide transmission line.

18. The gap waveguide transmission device according to claim 1, characterized in that, The shape of the protrusions and grooves of the corrugated grooves can be any one of the following: rectangular, triangular, semi-circular, trapezoidal, or elliptical.

19. A method for manufacturing a gap waveguide transmission device based on artificial surface plasmons according to any one of claims 1 to 16 comprises: Two transmission structures are provided, wherein at least one waveguide transmission structure has a groove on the surface opposite to the other waveguide transmission structure, and a conductive layer is provided on the opposite surfaces of the two transmission structures, the conductive layer covering the groove. A corrugated groove is formed on the outer wall of the groove, and the corrugated groove is fixedly electrically connected to the conductive layer of at least one of the two waveguide transmission structures; the two waveguide transmission structures are installed so that the conductive layer covering the groove and the conductive layer of the other waveguide transmission structure form a strip-shaped waveguide transmission channel.

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