阅读说明：本技术 基于siw的太赫兹传输结构及其制备方法和应用 (Terahertz transmission structure based on SIW (substrate integrated waveguide) and preparation method and application thereof ) 是由 丁丽 李萍 朱亦鸣 熊毓俊 鲍佳宸 于 2020-05-07 设计创作，主要内容包括：本发明提出了基于SIW的太赫兹传输结构及其制备方法和应用,该结构包括第一传输线、第二传输线和耦合传输线,第一传输线和第二传输线包括介质基片、设置于第一传输线介质基片下表面的金属镀铜层、第二传输线介质基片上表面的金属铜镀层、第一传输线介质基片上表面带有耦合窗开口的金属铜镀层和第二传输线介质基片下表面带有耦合窗开口的金属铜镀层；第一传输线和耦合传输线垂直,耦合传输线与第二传输线垂直；介质基片上设置两排平行的金属通孔贯穿介质基片与上下表面形成基片集成波导结构。本发明传输结构在转接处用基片集成波导替代了传统金属波导,避免了垂直转接处高次模的形成,完成了有垂直距离差太赫兹波等效波导口的创造。(The invention provides a terahertz transmission structure based on SIW (substrate integrated waveguide), a preparation method and application thereof, wherein the structure comprises a first transmission line, a second transmission line and a coupling transmission line, wherein the first transmission line and the second transmission line comprise dielectric substrates, metal copper plating layers arranged on the lower surfaces of the dielectric substrates of the first transmission line, metal copper plating layers on the upper surfaces of the dielectric substrates of the second transmission line, metal copper plating layers with coupling window openings on the upper surfaces of the dielectric substrates of the first transmission line and metal copper plating layers with coupling window openings on the lower surfaces of the dielectric substrates of the second transmission line; the first transmission line is vertical to the coupling transmission line, and the coupling transmission line is vertical to the second transmission line; two rows of parallel metal through holes are arranged on the dielectric substrate and penetrate through the dielectric substrate and the upper surface and the lower surface to form a substrate integrated waveguide structure. The transmission structure of the invention replaces the traditional metal waveguide with the substrate integrated waveguide at the switching position, avoids the formation of a higher-order mode at the vertical switching position and completes the creation of a terahertz wave equivalent waveguide port with vertical distance difference.)

1. SIW-based terahertz transmission structure, comprising a SIW transmission structure (1), characterized in that the SIW transmission structure (1) comprises a first transmission line (2), a second transmission line (3) and a coupling transmission line (4);

the first transmission line (2) is vertical to the coupling transmission line (4);

the coupling transmission line (4) is vertical to the second transmission line (3);

the SIW transmission structure (1) is in a step shape.

2. The SIW-based terahertz transmission structure according to claim 1, wherein the first transmission line dielectric substrate end forms an enlarged field region through the parallel through-hole, thereby creating a coupling window of the E-plane probe to connect with the coupling transmission line;

and the other end of the coupling transmission line is connected with the coupling window of the second transmission line dielectric substrate.

3. The preparation method of the terahertz transmission structure based on the SIW is characterized by comprising the following steps of:

step 1, according to the WR-4.3 wave band substrate integrated waveguide width W and rectangular waveguide width W_effEquivalence relation between

step 2, according to the SIW design principle of the equivalent formula in the step 1 and the condition limitation of eliminating the electromagnetic stop-band effect parameters, parameter scanning is respectively carried out on the parameters d, s and w obtained in the step 1, and the sizes of the first, second and coupling transmission lines are further optimized;

and step 3: constructing the first transmission line, the second transmission line and the coupling transmission line with the optimized sizes obtained in the step (2) into a step-shaped structure, wherein the first transmission line is vertical to the coupling transmission line, and the coupling transmission line is vertical to the second transmission line; then, setting an expanded field range at the tail ends of the first transmission line and the second transmission line by changing the layout of the metal through holes, and performing parameter scanning on the length and the width of the expanded field range to ensure that the maximum electric field strength value and the maximum return loss are achieved under the condition that a high-order mode and electromagnetic leakage are not generated;

and 4, step 4: and (3) setting a structure-coupling window which is connected with the coupling transmission line and performs waveguide coupling and mode conversion in the expanded field range of the tail end of the SIW transmission line with the optimized size obtained in the step (3), and scanning the size parameters of the coupling window to determine the accurate size of each part of the structure so as to complete the construction of the whole SIW transmission structure.

4. The SIW-based terahertz transmission structure as claimed in any one of claims 1-2 is used as a connection port for connection of terahertz devices on different horizontal planes and long-distance low-loss transmission and switching of terahertz waves.

Technical Field

The invention relates to the field of microwave, transmission line and coaxial coupling, in particular to a terahertz transmission structure based on SIW and a preparation method and application thereof.

Background

In recent years, the research on the terahertz transmission line technology has been greatly developed. After the conventional waveguide, microstrip-type structures such as a strip line, a microstrip line, a slot line, and the like are successively formed. The above transmission lines have their own advantages and disadvantages. The traditional waveguide has the advantages of high transmission power, good transmission performance and low loss, but has a large volume and is difficult to integrate with other components; the microstrip type structure is small in size, easy to integrate and large in loss.

Substrate Integrated waveguide (siw) is a new type of transmission line structure that can be Integrated in dielectric substrates, because of its stable characteristic transmission performance and good compatibility used in increasingly higher frequency bands. SIW is usually obtained by drilling two rows of metal vias on a dielectric substrate and then coating the substrate with metal on both sides. Under the condition of ensuring that energy on the transmission line is not leaked, the through hole array is equivalent to a metal wall, and the transmission characteristic can be approximately analyzed by rectangular waveguide. The SIW structure has the advantages of the conventional waveguide and microstrip transmission line, i.e., low radiation, low insertion loss, high Q value, miniaturization, easy integration, etc., and can integrate communication devices such as passive devices, active devices, antennas, etc. on the same substrate. However, the SIW with the conventional structure cannot satisfy the integration of devices with ports not in the same plane.

Disclosure of Invention

The invention aims to provide a terahertz transmission structure based on SIW (substrate integrated waveguide) and a preparation method and application thereof aiming at the condition that the inherent physical size of a transmitting and receiving module of a single-station imaging system causes the limitation of the azimuth physical interval, so that the connection of devices with ports not on the same plane is realized, and the terahertz transmission structure has good transmission performance in an effective bandwidth.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows: SIW-based terahertz transmission structure comprising a SIW transmission structure (1), the SIW transmission structure (1) comprising a first transmission line (2), a second transmission line (3) and a coupling transmission line (4);

the first transmission line (2) is vertical to the coupling transmission line (4);

the coupling transmission line (4) is vertical to the second transmission line (3);

the SIW transmission structure (1) is in a step shape.

Further, the tail end of the first transmission line medium substrate forms an expanded field area through the parallel through hole, so that a coupling window of the E-plane probe is established to be connected with the coupling transmission line;

and the other end of the coupling transmission line is connected with the coupling window of the second transmission line dielectric substrate.

A preparation method of a terahertz transmission structure based on SIW comprises the following steps:

step 1, according to the WR-4.3 wave band substrate integrated waveguide width W and rectangular waveguide width W_effEquivalence relation betweenObtaining the resonant center frequency f of the first transmission line, the second transmission line and the coupling transmission line₀The diameter d of the metal through hole and the distance s between the centers of circles of the adjacent metal through holes;

step 2, according to the SIW design principle of the equivalent formula in the step 1 and the condition limitation of eliminating the electromagnetic stop-band effect parameters, parameter scanning is respectively carried out on the parameters d, s and w obtained in the step 1, and the sizes of the first, second and coupling transmission lines are further optimized;

and step 3: constructing the first transmission line, the second transmission line and the coupling transmission line with the optimized sizes obtained in the step (2) into a step-shaped structure, wherein the first transmission line is vertical to the coupling transmission line, and the coupling transmission line is vertical to the second transmission line; then, setting an expanded field range at the tail ends of the first transmission line and the second transmission line by changing the layout of the metal through holes, and performing parameter scanning on the length and the width of the expanded field range to ensure that the maximum electric field strength value and the maximum return loss are achieved under the condition that a high-order mode and electromagnetic leakage are not generated;

and 4, step 4: and (3) setting a structure-coupling window which is connected with the coupling transmission line and performs waveguide coupling and mode conversion in the expanded field range of the tail end of the SIW transmission line with the optimized size obtained in the step (3), and scanning the size parameters of the coupling window to determine the accurate size of each part of the structure so as to complete the construction of the whole SIW transmission structure.

The terahertz transmission structure based on the SIW is used as a connecting port for connecting terahertz devices on different horizontal planes and transmitting and switching terahertz waves at a low loss and a long distance.

Compared with the prior art, the invention has the advantages that: according to the invention, three sections of basic transmission lines, namely the first transmission line, the second transmission line and the coupling transmission line, are established into a step-shaped structure, so that the connection of devices with ports not on the same plane is realized, the difference of the azimuth-direction vertical distance of a waveguide port caused by the inherent size of the device in a single-station imaging system is eliminated, the low-loss transmission of THz waves of 45mm is completed, and the coupling transmission performance has 20% of relative bandwidth in a WR-4.3 waveband.

Drawings

Fig. 1 is a top view of a first transmission line and a second transmission line of a terahertz transmission structure based on SIW in an embodiment of the present invention.

Fig. 2 is a structural diagram of a terahertz transmission structure based on SIW in an embodiment of the present invention, where (a) is a schematic diagram of a terahertz transmission structure based on SIW, and (b) is a schematic diagram of an entire terahertz transmission structure based on SIW.

Fig. 3 is a schematic diagram of a terahertz wavelength distance transmission structure created by the coupling transmission line of the present invention.

Fig. 4 is a simulation result of the S11 parameter of the terahertz transmission structure based on SIW in the WR-4.3 band according to the embodiment of the present invention.

Fig. 5 is a simulation result of the S21 parameter of the terahertz transmission structure based on SIW in the WR-4.3 band according to the embodiment of the present invention.

Fig. 6 is a VSWR curve of the SIW-based terahertz transmission structure in the embodiment of the present invention.

Fig. 7 shows propagation constants of the terahertz transmission structure based on SIW in the embodiment of the present invention.

Fig. 8 shows the attenuation constant of the SIW-based terahertz transmission structure in the embodiment of the present invention.

FIG. 9 is a diagram showing an electric field distribution formed by transmission of terahertz waves in the coupling transmission line according to the present invention.

Fig. 10 is a scene diagram of the same scale for practical application of the present invention.

Detailed Description

The technical solution adopted by the present invention will be further explained with reference to the schematic drawings.

The terahertz transmission structure 1 based on SIW provided by the invention comprises three sections of basic transmission lines, namely a first transmission line 2, a second transmission line 3 and a coupling transmission line 4, wherein the top views of the first transmission line and the second transmission line are shown in figure 1, the first transmission line 2 and the second transmission line 3 comprise a dielectric substrate 5, metal copper coatings arranged on the lower surface of the dielectric substrate of the first transmission line and the upper surface of the dielectric substrate of the second transmission line (the metal copper coating on the lower surface of the dielectric substrate of the first transmission line is defined as a first metal copper coating 6, the metal copper coating on the upper surface of the dielectric substrate of the second transmission line is defined as a second metal copper coating 7) and metal copper coatings with openings of coupling windows 8 on the upper surface of the dielectric substrate of the first transmission line and the lower surface of the dielectric substrate of the second transmission line (the metal copper coating with the openings of the coupling windows on the upper surface of the dielectric substrate of the first transmission line is defined as a third metal copper, the metal copper plating layer with the coupling window opening on the lower surface of the second transmission line dielectric substrate is defined as a fourth metal copper plating layer 10). The first transmission line is vertical to the coupling transmission line, and the coupling transmission line is vertical to the second transmission line to form a ladder structure; two rows of parallel metal through holes 11 are arranged on the dielectric substrate and penetrate through the dielectric substrate and the upper surface and the lower surface to form a substrate integrated waveguide structure. The transmission performance of the whole SIW transmission structure can be changed by adjusting the structure parameters of the first transmission line and the second transmission line, the length of the coupling transmission line and the size of the coupling window.

As can be seen in fig. 2, the SIW-based terahertz transmission structure includes a first transmission line 2, a second transmission line 3 and a coupling transmission line 4, the first transmission line and the second transmission line include a dielectric substrate (5), a first metal copper plating layer 6 disposed on a lower surface of the dielectric substrate of the first transmission line, a second metal copper plating layer 7 on an upper surface of the dielectric substrate of the second transmission line, a third metal copper plating layer 9 with an opening of a coupling window 8 on the upper surface of the dielectric substrate of the first transmission line, and a fourth metal copper plating layer 10 with an opening of a coupling window on a lower surface of the dielectric substrate of the second transmission line; the first transmission line is vertical to the coupling transmission line, and the coupling transmission line is vertical to the second transmission line; two rows of parallel metal through holes 11 are arranged on the dielectric substrate and penetrate through the dielectric substrate and the upper surface and the lower surface to form a substrate integrated waveguide structure. The transmission structure of the invention replaces the traditional metal waveguide with the substrate integrated waveguide at the switching position, avoids the formation of a higher-order mode at the vertical switching position and completes the creation of a terahertz wave equivalent waveguide port with vertical distance difference.