CN114171872B

CN114171872B - Broadband miniaturized millimeter wave double-channel cross bridge

Info

Publication number: CN114171872B
Application number: CN202111419255.8A
Authority: CN
Inventors: 连继伟; 胡鹏; 丁大志
Original assignee: Nanjing University of Science and Technology
Current assignee: Nanjing University of Science and Technology
Priority date: 2021-11-26
Filing date: 2021-11-26
Publication date: 2023-04-21
Anticipated expiration: 2041-11-26
Also published as: CN114171872A

Abstract

The invention discloses a broadband miniaturized millimeter wave double-channel cross bridge, which comprises a medium substrate, a first metal structure printed at the bottom of the medium substrate, a second metal structure printed at the top of the medium substrate, and a plurality of metal through holes distributed on the medium substrate, wherein the first metal structure is printed on the bottom of the medium substrate; etching air cavity structures which are mutually crossed and symmetrical at the central position of the dielectric substrate, wherein the air cavity structures are at a certain distance from the metal through holes; inside the center of the air chamber is a cylindrical uniform lens. The S11 is smaller than ‒ dB from 25.8GHz to 38.3GHz, and the corresponding impedance bandwidth is 33%; the insertion loss of the broadband millimeter wave double-channel cross bridge is in the range of 0.1dB to 0.5dB in the target frequency band.

Description

Broadband miniaturized millimeter wave double-channel cross bridge

Technical Field

The invention relates to the application field of cross bridges, in particular to a double-channel broadband millimeter wave cross bridge working in a millimeter wave frequency band.

Background

A crossover bridge is a passive component that allows multiple transmission lines or signal paths to geometrically intersect each other while maintaining good isolation between the paths. With the development of miniaturization and versatility of microwave and millimeter wave radio frequency circuits and integrated circuits, crossover bridges inevitably play a more important role because they can effectively solve the multi-path crossover problem. The cross-bridges at microwave frequencies reported in the earlier literature are mostly based on microstrip technology and waveguide technology. In recent years, as millimeter wave and terahertz frequency bands have richer and unassigned spectrum resources, cross bridges operating in millimeter wave and terahertz frequency bands are increasingly receiving attention from academia and industry.

It is worth noting that, in order to overcome the serious radiation loss of the microstrip line in the frequency band above millimeter wave, the closed structure such as the substrate integrated waveguide is a more popular transmission line form. However, such transmission lines often suffer from the disadvantage of larger dimensions compared to microstrip lines; and the cross bridge designed by the substrate integrated structure has insufficient bandwidth, usually only about 10 percent. Under the condition, the invention provides a cross bridge with broadband and miniaturization characteristics, which is more beneficial to the integrated and miniaturized design of a circuit.

Disclosure of Invention

The invention aims to provide a broadband miniaturized millimeter wave double-channel cross bridge, which further improves the bandwidth of the millimeter wave cross bridge and is used for solving the problems of narrower bandwidth and larger device size in a target frequency band.

The technical scheme adopted by the invention is as follows: a double-channel broadband millimeter wave crossover bridge comprises a dielectric substrate, a first metal structure printed at the bottom of the dielectric substrate, a second metal structure printed at the top of the dielectric substrate and metal through holes distributed on the dielectric substrate; etching air cavity structures which are mutually crossed and symmetrical in the middle of the dielectric substrate, wherein the air cavity structures are at a certain distance from the metal through holes; a cylindrical uniform lens is arranged in the center of the air cavity.

The dielectric substrate material is Rogers RT/duroid 5880.

The first metal structure and the second metal structure are made of copper.

The metal through holes are arranged in a straight line in two rows and two columns, wherein the two columns are parallel, the two rows are parallel, and the rows and the columns of the metal through holes are mutually crossed and perpendicular.

The diameter of the metal through holes is 0.4mm, the height of the metal through holes is 0.787mm, and the distance between adjacent metal through holes is 0.8mm.

The air cavity structure is arranged between two rows and two columns of metal through holes, and the width is 7.2mm.

The cylindrical uniform lens diameter was 4mm and the height was 0.787mm.

The dielectric substrate has a size of 59.2mm by 0.787mm.

Compared with the prior art, the invention has the beneficial effects that:

(1) Aiming at the problem of serious radiation loss of the microstrip line in the frequency band above millimeter waves, the substrate integration technology is applied to the design of the cross bridge, and the closure, the integration and the low-loss characteristic of the cross bridge are effectively improved.

(2) Aiming at the problem that the space occupied by the prior structure is too large, the invention digs the space of the substrate to construct the cylindrical uniform lens without increasing the occupied space, thereby keeping the compact structure. And the structure can be processed by the traditional printed circuit board technology and can be used for large-scale and low-cost production.

(3) A significant bandwidth boost is achieved. The relative impedance bandwidth of the invention is 33%, and the reflection coefficient and the isolation coefficient are smaller than-15 dB in the frequency band range from 25.8GHz to 38.3 GHz. Far exceeding the effect of the present millimeter wave substrate integrated waveguide cross bridge.

Drawings

Fig. 1 is a plan view of a broadband miniaturized millimeter wave dual-channel cross bridge of the present invention.

Fig. 2 is a plan view of a broadband miniaturized millimeter wave dual-channel cross bridge (excluding transition structures) of the present invention.

Fig. 3 is a schematic diagram of S-parameters of a broadband miniaturized millimeter wave dual-channel cross bridge (excluding transition structures) of the present invention.

Fig. 4 is a schematic diagram of the design process of the broadband miniaturized millimeter wave dual-channel cross bridge of the present invention.

Fig. 5 is an E-plane electric field distribution diagram of the broadband miniaturized millimeter wave dual-channel cross bridge simulation of the present invention.

Fig. 6 is a diagram showing comparison of S parameters for simulation and testing of the broadband miniaturized millimeter wave dual-channel cross bridge of the present invention.

Detailed Description

With the rapid development of millimeter wave communication systems, millimeter wave cross bridges have received a great deal of attention. While the present cross bridge invention for millimeter waves is less. And its impedance bandwidth tends to be less than 20%.

The invention is further described below with reference to the drawings and examples.

The invention provides a broadband miniaturized millimeter wave double-channel cross bridge, which mainly comprises a coplanar waveguide feed structure, a substrate integrated waveguide, an air cavity structure and a cylindrical uniform lens; after the energy is fed by the coplanar waveguide, it enters the air cavity through the transition structure, is then focused by the cylindrical uniform lens and reaches another output port.

Firstly, constructing a coplanar waveguide feed structure, wherein the component parts of the coplanar waveguide feed structure comprise a substrate which is taken as a first dielectric substrate and three conduction bands, two sides of the three conduction bands are grounded rewinding belts, and the middle of the three conduction bands is a metal conduction band which is very close to the grounded conduction band and parallel to the grounded conduction band.

Subsequently, a transition structure from the coplanar waveguide to the substrate integrated waveguide is designed. There are two rows and two columns of metal through holes 6 on the dielectric substrate 1, which simulate the two sidewalls of a conventional waveguide. And finally, constructing a quasi-closed substrate integrated waveguide transmission structure by the metal interfaces at the top and the bottom and the two rows of metal through holes 6.

Subsequently, a hole is drilled in the dielectric substrate 1, and an air cavity structure 4 is dug out, the center of which is aligned with the dielectric substrate 1.

Finally, a cylindrical uniform lens is added at the center of the air cavity structure 4, so that the design of a millimeter wave double-channel cross bridge is realized.

Further, the material of the dielectric substrate 1 is Rogers RT/duroid 5880, and the size is 59.2mm by 0.787mm.

Further, the diameter of the metal through holes 6 is 0.4mm, the height is 0.787mm, and the distance between adjacent metal through holes 6 is 0.8mm.

Examples

Fig. 1 shows a complete design model of the present invention. The design model of the invention without transition structure is shown in fig. 2, and the S parameters obtained by simulation are shown in fig. 3. From 25.8GHz to 38.3GHz, S11 is less than-15 dB, corresponding to an impedance bandwidth of 33%. The broadband miniaturized millimeter wave double-channel cross bridge insertion loss of the invention ranges from 0.1dB to 0.5dB in the target frequency band. A complete simulation model containing the transition structure is shown in fig. 3. The invention mainly comprises a coplanar waveguide feed structure, a substrate integrated waveguide, an air cavity and a cylindrical uniform lens; the coplanar waveguide feed structure comprises a substrate which is taken as a dielectric substrate and three conduction bands, wherein two sides of the three conduction bands are grounded rewinding belts, and the middle of the three conduction bands is very close to the grounded conduction band and is parallel to the grounded conduction band and is a metal conduction band; the substrate integrated waveguide feed structure consists of a medium substrate 1, a first metal structure 2 printed at the bottom of the medium substrate 1, a second metal structure 3 printed at the top of the medium substrate 1, an air cavity structure 4, a cylindrical uniform lens 5 and metal through holes 6 distributed on the medium substrate 1; after the energy is fed by the substrate integrated waveguide, it reaches another output port through the air cavity structure and CHL.

To explore the working principle of the present invention, the implementation of the present invention is broken down into

states

1 and 2, as shown in fig. 4. In state 1, the air cavity is removed and all areas are filled with medium. State 2 is to add an air cavity structure and a cylindrical uniform lens on the basis of state 1. Fig. 5 (a) shows the electric field distribution of the open structure of the substrate integrated waveguide without the cylindrical uniform lens, and fig. 5 (b) shows the electric field distribution of the open structure of the substrate integrated waveguide with the cylindrical uniform lens. It can be seen that the electric field of fig. 5 (b) is confined near the cylindrical uniform lens corresponding to state 2, most of the energy propagating towards the other port; conversely, if the cylindrical uniform lens is removed, the electric field will spread out and severe energy leakage will occur.

The reflection coefficient and isolation coefficient for the simulation and test are given in fig. 6. In the simulation, from 25.8GHz to 38.3GHz, the reflection coefficient and the isolation coefficient are both smaller than-15 dB, the corresponding impedance bandwidth is 33%, the insertion loss is minimum at 0.9dB, S21 is smaller than-15 dB, S11 is smaller than-13 dB from 25.8GHz to 34.6GHz, and the insertion loss is minimum at 2.6dB. It can be seen that the maximum difference between simulation and measurement is the insertion loss, which is about 1.7dB. This difference is mainly due to the insertion loss of the connector, the insertion loss of the connection between the connector and the coplanar waveguide, and the errors in the manufacturing process.

The above embodiments are merely illustrative of the principles of the present invention and its effectiveness, and are not intended to limit the invention. Modifications and variations may be made to the above-described embodiments by those skilled in the art without departing from the spirit and scope of the invention. Accordingly, it is intended that all equivalent modifications and variations of the invention be covered by the claims, which are within the ordinary skill of the art, be within the spirit and scope of the present disclosure.

Claims

1. A broadband miniaturized millimeter wave double-channel cross bridge is characterized in that: the device comprises a medium substrate (1), a first metal structure (2) printed at the bottom of the medium substrate (1), a second metal structure (3) printed at the top of the medium substrate (1), a cylindrical uniform lens (5) and a plurality of metal through holes (6) distributed on the medium substrate (1); the center of the dielectric substrate (1) is etched with mutually crossed and symmetrical air cavity structures (4), and a distance is reserved between each air cavity structure (4) and each metal through hole (6); the metal through holes (6) are arranged in a straight line in two rows and two columns, wherein the two columns are parallel, the two rows are parallel, and the rows and the columns of the metal through holes (6) are mutually crossed and perpendicular; the air cavity structure (4) is positioned between two rows and two columns of metal through holes (6); the central part of the air cavity structure (4) is provided with a cylindrical uniform lens (5).

2. The broadband miniaturized millimeter wave dual-channel cross bridge of claim 1, wherein: the material of the dielectric substrate (1) is Rogers RT/duroid 5880.

3. The broadband miniaturized millimeter wave dual-channel cross bridge of claim 1, wherein: the first metal structure (2) and the second metal structure (3) are made of copper.

4. The broadband miniaturized millimeter wave dual-channel cross bridge of claim 1, wherein: the diameter of the metal through holes (6) is 0.4mm, the height of the metal through holes is 0.787mm, and the distance between adjacent metal through holes (6) is 0.8mm.

5. The broadband miniaturized millimeter wave dual-channel cross bridge of claim 1, wherein: the width of the air cavity structure (4) is 7.2mm.

6. The broadband miniaturized millimeter wave dual-channel cross bridge according to claim 1, characterized in that said cylindrical uniform lens (5) has a diameter of 4mm and a height of 0.787mm.

7. The broadband miniaturized millimeter wave dual-channel crossover bridge according to claim 1, wherein the dielectric substrate (1) has dimensions 59.2mm by 0.787mm.