CN217507641U - Planar microstrip-to-gap waveguide antenna - Google Patents

Abstract

The utility model relates to a planar microstrip-to-gap waveguide antenna, which comprises a laminated structure, a microstrip structure and a gap waveguide structure; the microstrip structure comprises a first microstrip line, an anti-impedance transformation unit and a second microstrip line, wherein the first microstrip line and the second microstrip line are connected through the anti-impedance transformation unit; the gap waveguide structure comprises a laminated structure, a metal plate, a plurality of mushroom-shaped through hole periodic structures, a plurality of micro-strip structures and a gap waveguide structure, wherein the laminated structure is provided with the mushroom-shaped through hole periodic structures, the metal plate is arranged above the laminated structure, the mushroom-shaped through hole periodic structures are distributed on the side face of the micro-strip structure, and the mushroom-shaped through hole periodic structures, the metal plate and the first micro-strip line jointly form the gap waveguide structure. The utility model ensures low loss of energy transmission by mixing the medium layer and the air layer; the microstrip structure can be integrated with other components or millimeter wave radar chips, so that the whole system is more compact and the processing cost is lower.

Description

Planar microstrip-to-gap waveguide antenna

Technical Field

The utility model relates to a clearance waveguide antenna field is changeed to plane microstrip, especially about a clearance waveguide antenna is changeed to plane microstrip.

Background

The millimeter wave band brings troubles to the design of a high-performance millimeter wave system due to more serious higher harmonic radiation effect, higher dielectric loss and other adverse factors. In planar or low profile applications, Substrate Integrated Waveguides (SIWs) of common microwave transmission lines such as microstrip lines, striplines and dielectrics have greatly reduced availability due to their large losses and other disadvantages. The gap waveguide is a novel waveguide structure, which is made of two parallel metal conductor plates, the upper layer metal plate is used as an ideal electric conductor (PEC), the lower layer metal plate is provided with a middle metal ridge/air slot and an Artificial Magnetic Conductor (AMC) formed by periodic metal nails at two sides, an air gap layer is arranged between the upper layer and the lower layer, electromagnetic waves can be propagated along the metal ridge/air slot, due to the structure of all metals, the gap waveguide also has the problem of difficult integration in a circuit, in order to improve the defect, researchers begin to consider using a Substrate Integrated Gap Waveguide (SIGW), the technology is based on the above, the gap is improved into a medium gap, the unstable factor of the air gap is improved, the processing is simpler and more convenient, but the problem that the loss of the medium substrate gap layer greatly affects energy transmission needs to be solved urgently.

In addition, in the millimeter wave band, the integrated design of the antenna and an active radio frequency circuit based on a Monolithic Microwave Integrated Circuit (MMIC) is very important, and for the gap waveguide slot antenna, the good energy transmission between the microstrip line and the gap waveguide is a key ring in the overall design, and the design of the transmission structure needs to have good impedance matching and integrated design. In the prior art, through coupling feed and direct contact feed, in a common gap waveguide slot antenna structure, energy transmission between a microstrip line and a gap waveguide adopts a coupling feed mode, if microstrip lines are directly laid between the upper surfaces of the printed circuit boards and coupled with the gap ridge waveguides, the PEC, whose lower surface acts as the gap waveguide, but usually there is a layer of PCB medium between the PEC on the top layer of the gap waveguide and the pin period, the dielectric layer causes a large degree of energy attenuation during the energy transmission process, although the improved microstrip-to-gap ridge waveguide, the reference PEC, which is the microstrip upper surface, eliminates the loss of the PCB medium, but also sacrifices the low profile of the structure as a whole, and the transmission efficiency is determined by the alignment effect of the top layer PCB microstrip patch and the bottom layer gap waveguide ridge structure, certain requirements are required for electronic assembly, and the high-integration integrated low-profile development of the system is not facilitated.

SUMMERY OF THE UTILITY MODEL

In view of this, the present invention provides a planar microstrip-to-gap waveguide antenna to solve the above technical problems.

The purpose of the utility model is realized through the following technical scheme:

a planar microstrip-to-gap waveguide antenna comprises a laminated structure, a microstrip structure and a gap waveguide structure; the laminated structure comprises m metal layers, the m metal layers are laminated, a dielectric layer is arranged between every two adjacent metal layers, and m is a natural number greater than 1; the microstrip structure is arranged on the uppermost metal layer and comprises a first microstrip line, an anti-impedance conversion unit and a second microstrip line, and the first microstrip line and the second microstrip line are connected through the anti-impedance conversion unit; the gap waveguide structure comprises a laminated structure, a metal plate, a plurality of mushroom-shaped through hole periodic structures, a plurality of micro-strip structures and a gap waveguide structure, wherein the laminated structure is provided with the mushroom-shaped through hole periodic structures, the metal plate is arranged above the laminated structure, the mushroom-shaped through hole periodic structures are distributed on the side face of the micro-strip structure, and the mushroom-shaped through hole periodic structures, the metal plate and the first micro-strip line jointly form the gap waveguide structure.

Compared with the air slot gap waveguide made of all metal, the planar microstrip rotating gap waveguide antenna can be formed by utilizing a multilayer PCB (printed Circuit Board) process through pattern etching, drilling and pressing, so that the process is greatly simplified, mass production with low cost is facilitated, the transmission characteristic can be controlled by utilizing parameters in a circuit and a PCB (printed Circuit Board), and waveguide energy transmission and tunable working frequency are realized; the low loss of energy transmission is ensured by the mixing mode of the dielectric layer and the air layer; the microstrip structure can be integrated with other components or millimeter wave radar chips, so that the whole system is more compact, the processing cost is lower, the gap waveguide structure can be connected with other waveguide structures or electronic equipment, a waveguide slot antenna can be connected at the short-circuit end, the integration of a feed radiation system is realized, and the application range of the antenna is enlarged.

Further, the laminated structure is configured as a first portion and a second portion, and the metal layer located inside is provided only to the second portion; the first microstrip line is arranged on the first part, and the metal plate is arranged above the first part; the second microstrip line and the anti-impedance transformation unit are arranged on the second part.

The laminated structure is divided into two parts, and the metal layer positioned inside is only arranged on the second part, namely the metal layer positioned in the first part can be etched by an etching process, the metal layer at the bottommost end can be referred to by the first microstrip line as a ground reference surface, the metal layer positioned in the second layer can be referred to by the impedance transformation unit and the second microstrip line as a ground reference surface, the second microstrip line can be integrated with other components and devices and a millimeter wave radar chip system, and the second microstrip line can be electrically connected with the first microstrip line and the impedance transformation unit in the same plane.

Further, mushroom-shaped through-hole periodic structure includes pad and electroplating through-hole, the pad is located the metal level of the top, electroplating through-hole with the pad is connected, and link up in m the metal level.

The welding disc in the mushroom-shaped through hole periodic structure is a circular welding disc, and the size of parameters of the through hole can be designed according to the working bandwidth tuning of the antenna structure and is used for blocking the leakage of electromagnetic waves.

Furthermore, a plurality of mushroom-shaped through hole periodic structures are positioned on two opposite sides of the microstrip structure in the length direction.

The mushroom-shaped through hole periodic structures are uniformly distributed on two opposite sides of the microstrip structure in the length direction, and two rows are arranged on each side, so that electromagnetic wave leakage is avoided to the greatest extent.

Furthermore, a plurality of mushroom-shaped through hole periodic structures are positioned on two opposite sides of the microstrip structure in the length direction and on one side of the first part in the width direction.

The mushroom-shaped through hole periodic structure is additionally arranged on the basis of two sides of the microstrip structure in the length direction, and one side of the mushroom-shaped through hole periodic structure in the width direction is additionally arranged to form short-circuit connection, so that the purpose of conveniently integrating a slot antenna is achieved, and the mushroom-shaped through hole periodic structure is favorable for radiating signals.

Furthermore, a plurality of waveguide slots are arranged on the metal plate.

The arrangement of the plurality of waveguide slots is used for controlling the current amplitude and phase distribution, so that a directional diagram of the antenna has the advantage of wide beam, the structure has a low section as a micro-strip transmission structure, the integration of a feed radiation system is realized, and the application range of the antenna structure is expanded.

Further, the plurality of waveguide slots are arranged at intervals, and the sizes of the plurality of waveguide slots can be different from each other.

The waveguide slot can obtain the requirement of amplitude phase distribution of the gap waveguide slot antenna by adjusting the size and the position of the waveguide slot, thereby having wider beam angle antenna performance and lower dielectric loss than the existing microstrip patch antenna.

Further, the waveguide slot is rectangular or elliptical in shape.

The shape of the waveguide slot can be flexibly adjusted according to actual test or processing requirements.

Further, the distance between the metal plate and the laminated structure is 0.2 mm.

The utility model discloses compare in prior art's beneficial effect and be:

compared with the air slot gap waveguide made of all metal, the utility model can utilize the multilayer PCB board process to realize the graphic etching, the drilling and the compression molding, greatly simplify the process, facilitate the mass production with low cost, and the transmission characteristic can be controlled by the parameters in the circuit and the PCB board, thus realizing the tunable waveguide energy transmission and the working frequency; the low loss of energy transmission is ensured by the mixing mode of the dielectric layer and the air layer; the microstrip structure can be integrated with other components or millimeter wave radar chips, so that the whole system is more compact, the processing cost is lower, the gap waveguide structure can be connected with other waveguide structures or electronic equipment, a waveguide slot antenna can be connected at the short-circuit end, the integration of a feed radiation system is realized, and the application range of the antenna is enlarged.

Drawings

Fig. 1 is a schematic view of an overall structure of a first embodiment of the present invention.

Fig. 2 is a left side view of fig. 1.

Fig. 3 is a cross-sectional view of the structure shown in fig. 2.

Fig. 4 is a top sectional view of a first embodiment of the present invention.

Fig. 5 is a schematic diagram of a transmission performance loss result according to the first embodiment of the present invention.

Fig. 6 is a schematic view of an overall structure of the second embodiment of the present invention.

Fig. 7 is a top sectional view of a second embodiment of the present invention.

Fig. 8 is a diagram illustrating a return loss result according to a second embodiment of the present invention.

Fig. 9 is a directional diagram of a second embodiment of the present invention.

Reference numerals: 1-a laminated structure; 11-a metal layer; 111-a first metal layer; 112-a second metal layer; 113-a third metal layer; 114-a fourth metal layer; 12-a dielectric layer; 121-a first dielectric layer; 122-a second dielectric layer; 123-a third dielectric layer; 2-a microstrip structure; 21-a first microstrip line; 22-an anti-impedance transformation unit; 23-a second microstrip line; 3-mushroom via periodic structure; 31-a pad; 32-electroplating through holes; 4-a metal plate; 41-waveguide slot.

Detailed Description

To facilitate understanding of those skilled in the art, the present invention will be described in further detail with reference to specific embodiments and drawings.

Referring to fig. 1-9, embodiments of the present invention include.

The first embodiment.

Referring to fig. 1 to 5, a planar microstrip-to-gap waveguide antenna includes a stacked structure 1, a microstrip structure 2, and a gap waveguide structure; the laminated structure 1 comprises m metal layers 11, the m metal layers 11 are laminated, a dielectric layer 12 is arranged between every two adjacent metal layers 11, and m is a natural number greater than 1; the microstrip structure 2 is arranged on the metal layer 11 at the uppermost end and comprises a first microstrip line 21, an anti-impedance transformation unit 22 and a second microstrip line 23, and the first microstrip line 21 and the second microstrip line 23 are connected through the anti-impedance transformation unit 22; the laminated structure 1 is provided with a plurality of mushroom-shaped through hole periodic structures 3, a metal plate 4 is arranged above the laminated structure 1, the mushroom-shaped through hole periodic structures 3 are distributed on the side face of the microstrip structure 2, and the mushroom-shaped through hole periodic structures 3, the metal plate 4 and the first microstrip line 21 jointly form a gap waveguide structure.

The metal plate 4 can freely and flexibly tune the distance between the metal plate and the laminated structure 1, so that the dielectric constant and the dielectric thickness processing deviation brought by a PCB laminating process are compensated, and the required working bandwidth is obtained. The distance between the metal plate 4 and the laminated structure 1 of this embodiment is 0.2 mm.

Referring to fig. 1 to fig. 3, in the present embodiment, m =4 is taken as an example, that is, the stacked structure 1 is sequentially arranged from top to bottom as a first metal layer 111, a first dielectric layer 121, a second metal layer 112, a second dielectric layer 122, a third metal layer 113, a third dielectric layer 123, and a fourth metal layer 114, the 4-layer PCB stacked structure 1 may be formed by any PCB prepreg and copper-clad plate according to design requirements, in order to improve the structure processibility and ensure low loss of energy transmission, the first dielectric layer 121 of the present embodiment uses a low-loss high-frequency copper-clad plate RO3003 with low dk and df, dk =3.1, df =0.0018, and the dielectric thickness h1=0.127 mm; the second dielectric layer 122 is made of prepregs dk =3.5, df =0.02 and h3= 0.22mm without metal layers on two sides, the third dielectric layer 123 is made of ordinary FR4 copper clad laminates dk =3.55, df =0.02 and has a thickness h2=0.2, of course, the second dielectric layer 122 and the third dielectric layer 123 can be made of the same material as the first dielectric layer 121, the material selection of the embodiment can effectively save the cost, and the materials are connected through a PCB multi-layer high-temperature lamination process technology to form a 4-layer PCB laminated structure 1, so that the laminated structure 1 is formed.

In addition, based on the first dielectric layer 121, a high-frequency copper-clad plate RO3003 is used, dk =3.1, df =0.0018, the dielectric thickness h1=0.127mm, the line width W2=0.295mm of the second microstrip line 23, the second microstrip line 23 is a standard 50-ohm impedance transmission line, the line width of the first microstrip line 21 has a small influence on the design, the embodiment is designed to be W1=0.295mm, the impedance transformation unit 22 is located in the microstrip structure 2 and the gap waveguide structure, and is designed to be L =0.34mm in length, and the line width W3=0.1 mm.

Compared with the air slot gap waveguide made of all metal, the planar microstrip rotating gap waveguide antenna can be formed by utilizing a multilayer PCB (printed Circuit Board) process through pattern etching, drilling and pressing, so that the process is greatly simplified, mass production with low cost is facilitated, the transmission characteristic can be controlled by utilizing parameters in a circuit and a PCB (printed Circuit Board), and waveguide energy transmission and tunable working frequency are realized; the low loss of energy transmission is ensured by the way of mixing the dielectric layer 12 and the air layer; the microstrip structure 2 can be integrated with other components or millimeter wave radar chips, so that the whole system is more compact, the processing cost is lower, the gap waveguide structure can be connected with other waveguide structures or electronic equipment, and the short-circuit end connection can be provided with a waveguide slot 41 antenna, so that the integration of a feed radiation system is realized, and the application range of the antenna is enlarged.

Referring to fig. 1, in the present embodiment, the stacked structure 1 is configured as a first portion and a second portion, and the metal layer 11 located inside is only disposed on the second portion; the first microstrip line 21 is arranged on the first part, and the metal plate 4 is arranged above the first part; the second microstrip line 23 and the anti-impedance transformation unit 22 are disposed in the second portion.

Specifically, the first portion includes a first metal layer 111, a first dielectric layer 121, a second dielectric layer 122, a third dielectric layer 123 and a fourth metal layer 114, and the second portion includes the first metal layer 111, the first dielectric layer 121, the second metal layer 112, the second dielectric layer 122, the third metal layer 113, the third dielectric layer 123 and the fourth metal layer 114, that is, the second metal layer 112 and the third metal layer 113 originally located on the first portion are etched away by pattern etching.

In this embodiment, the laminated structure 1 is divided into two parts, and the metal layer located inside is only disposed on the second part, that is, the metal layer originally located on the first part can be etched away by an etching process, the first microstrip line 21 can refer to the metal layer at the bottom as a ground reference surface, the anti-impedance transformation unit 22 and the second microstrip line 23 can refer to the metal layer located on the second layer as a ground reference surface, the second microstrip line 23 can be integrated with other components and millimeter wave radar chip systems, and the second microstrip line 23 can be electrically connected with the first microstrip line 21 and the anti-impedance transformation unit 22 in the same plane.

Referring to fig. 2 and 3, in the present embodiment, the mushroom-shaped via periodic structure 3 includes a pad 31 and a plated via 32, the pad 31 is located at the uppermost metal layer, and the plated via 32 is connected to the pad 31 and penetrates through m metal layers.

Specifically, the pad 31 in the mushroom-shaped via periodic structure 3 is a circular pad 31, and the size of the via parameter can be tuned according to the working bandwidth of the antenna structure, so as to block the leakage of electromagnetic waves. The pad 31 is disposed on the first metal layer 111, and the plated through hole 32 penetrates through to the fourth metal layer 114. The design of this embodiment is 75-80GHz, the aperture d1=0.5mm of the circular pad 31, and the diameter d2=0.25 of the through hole.

Referring to fig. 4, in the present embodiment, the mushroom-shaped via periodic structures 3 are located on two opposite sides of the microstrip structure 2 in the length direction. The mushroom-shaped through hole periodic structures 3 are uniformly distributed on two opposite sides of the microstrip structure 2 in the length direction, and two rows are arranged on each side to avoid leakage of electromagnetic waves to the maximum extent. Specifically, the number of the mushroom-shaped via periodic structures 3 in each row is 13, and the distance S =0.75mm between the two rows of mushroom-shaped via periodic structures 3.

Referring to fig. 5, the transmission performance S11 and S21 loss results of the antenna of the present embodiment are schematically shown, which have better transmission performance at 75-80GHz, return loss S11 at 77GHz operating frequency is about-25 dB, and insertion loss S21 is about 1.16 dB.

Example two.

Referring to fig. 6 and fig. 7, unlike the first embodiment, the mushroom-shaped via periodic structures 3 of the present embodiment are located on two opposite sides of the microstrip structure 2 in the length direction and on one side of the first portion in the width direction. That is, on the basis that the two sides of the mushroom-shaped through hole periodic structures 3 in the length direction of the microstrip structure 2 are arranged, one side in the width direction of the mushroom-shaped through hole periodic structures is additionally arranged, specifically, one side of the first microstrip line 21 forms a short circuit connection, and the purpose is to conveniently integrate a slot antenna and facilitate the radiation of signals. Specifically, in the present embodiment, 23 mushroom-shaped via periodic structures 3 are located on both sides of the microstrip structure 2, and two rows of 5 mushroom-shaped via periodic structures 3 are located on one side of the first microstrip line 21.

In the present embodiment, the metal plate 4 is provided with a plurality of waveguide slits 41. The arrangement of the waveguide slots 41 is used for controlling the current amplitude and phase distribution, so that the directional diagram has the advantage of wide beam, the structure has a low section as a microstrip transmission structure, the integration of a feed radiation system is realized, and the application range of the antenna structure is expanded.

Specifically, the plurality of waveguide slots 41 are arranged at intervals, and the sizes of the plurality of waveguide slots 41 may be different from each other. The amplitude phase distribution requirement of the gap waveguide slot 41 antenna is obtained by adjusting the size and the position, so that the microstrip patch antenna has wider beam angle antenna performance and lower dielectric loss than the existing microstrip patch antenna.

In addition, the shape of the waveguide slot 41 of the present embodiment is a rectangle or an ellipse. The shape of the waveguide slot 41 can be flexibly adjusted according to actual test or processing requirements, and the embodiment is preferably rectangular.

Referring to fig. 8 and 9, through tests, the antenna of the present embodiment has a wider beam angle antenna performance than the existing microstrip patch antenna, and a lower dielectric loss, the reflection coefficient return loss can reach less than-10 dB in a broadband range of 76.5-79GHz, the directional diagram has a wide beam advantage, and the 3dB beam width angle with phi =0 ° reaches about 110 ° in a working frequency range of 77-79 GHz; the structure has the same low profile as a microstrip transmission structure, can be used as a novel antenna structure technology compatible with the advantages of a microstrip and gap waveguide structure, is expected to be integrated with other analog/digital electronic ICs or component whole systems, solves the problems of radiation interference and the like of a microstrip patch antenna in a millimeter wave frequency band, and can be applied to various fields such as vehicle-mounted millimeter wave radars, smart homes, health monitoring and the like.

Of course, as another embodiment, the laminated structure 1 may also be provided with 8 metal layers to meet the requirements of antenna structures and other digital signals or system layout and wiring, which is beneficial to the development of integration of the whole digital analog electronic system.

In the description of the present invention, it is to be understood that the terms such as "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore, should not be construed as limiting the present invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically limited otherwise.

While the invention has been described in conjunction with the specific embodiments set forth above, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications, and variations that fall within the spirit and scope of the appended claims.

Claims (9)

1. A planar microstrip-to-gap waveguide antenna is characterized by comprising a laminated structure, a microstrip structure and a gap waveguide structure;

the laminated structure comprises m metal layers, the m metal layers are laminated, a dielectric layer is arranged between every two adjacent metal layers, and m is a natural number greater than 1;

the microstrip structure is arranged on the uppermost metal layer and comprises a first microstrip line, an anti-impedance transformation unit and a second microstrip line, and the first microstrip line and the second microstrip line are connected through the anti-impedance transformation unit;

the gap waveguide structure comprises a laminated structure, a metal plate, a plurality of mushroom-shaped through hole periodic structures, a plurality of micro-strip structures and a gap waveguide structure, wherein the laminated structure is provided with the mushroom-shaped through hole periodic structures, the metal plate is arranged above the laminated structure, the mushroom-shaped through hole periodic structures are distributed on the side face of the micro-strip structure, and the mushroom-shaped through hole periodic structures, the metal plate and the first micro-strip line jointly form the gap waveguide structure.

2. The planar microstrip to gap waveguide antenna of claim 1, wherein the laminated structure is configured as a first portion and a second portion, and the metal layer located inside is provided only in the second portion; the first microstrip line is arranged on the first part, and the metal plate is arranged above the first part; the second microstrip line and the anti-impedance transformation unit are arranged on the second part.

3. The planar microstrip to gap waveguide antenna of claim 1 wherein the mushroom via periodic structure comprises a pad and a plated via, the pad is located at the uppermost metal layer, and the plated via is connected to the pad and penetrates m metal layers.

4. The planar microstrip to gap waveguide antenna of claim 2 wherein a plurality of said mushroom via periodic structures are located on opposite sides of said microstrip structure in a length direction.

5. The planar microstrip transition gap waveguide antenna according to claim 2, wherein a plurality of said mushroom via hole periodic structures are located at opposite sides of said microstrip structure in the length direction and at one side of said first portion in the width direction.

6. The planar microstrip to gap waveguide antenna according to claim 5, wherein said metal plate is provided with a plurality of waveguide slots.

7. The planar microstrip to gap waveguide antenna according to claim 6, wherein the plurality of waveguide slots are spaced apart, and the plurality of waveguide slots may be different in size.

8. The planar microstrip to gap waveguide antenna according to claim 6 or 7, wherein the waveguide slot is rectangular or elliptical in shape.

9. The planar microstrip to gap waveguide antenna of claim 1 wherein the distance between said metal plate and said laminated structure is 0.2 mm.

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