WO2013029372A1 - Microstrip - Google Patents

Abstract

The present invention relates to the field of microstrip. Provided is a microstrip. The microstrip comprises a metal strip, a dielectric substrate, and a ground plate. The microstrip also comprises a metamaterial thin film. The metamaterial thin film and the metal strip are arranged on one side of the dielectric substrate and are both affixed to the dielectric substrate. The metamaterial thin film covers the metal strip. The ground plate is arranged on the other side of the dielectric substrate. The microstrip of the present invention allows for effective inhibition of space wave leakage, thus solving the problem of electromagnetic wave crosstalk between microstrips.

Description

 microstrip line

[Technical Field]

The present invention relates to the field of microstrip lines and, more particularly, to a microstrip line.

 【Background technique】

Microstrip Line is a hybrid microwave integrated circuit (Hybrid Microwave) Integrated Circuits, HMIC) and Monolithic Microwave Integrated Circuits (Monolithic Mictowave Integrated One of the most widely used planar transmission lines in Circuits, MMIC. As shown in FIG. 1, from the structural point of view, the microstrip line is placed on the grounding plate 3 by a very thin metal strip 1 at a distance much smaller than the wavelength, and the metal strip 1 and the grounding plate 2 are separated by the dielectric substrate 3. open.

The outstanding advantage of the microstrip line is that it is compact and lightweight, and can be used to make complex microwave circuits in a small volume by stereolithography, photolithography, etching, etc., and is easy to integrate with other microwave devices to realize microwave components and systems. Integration.

With the increasing miniaturization of microwave components and systems, in some cases where volume and weight are demanding, microstrip transmission lines can be used instead of waveguides to form microwave circuits and form various complex planar circuits on the same substrate, including Bridge circuit, matching load, attenuator antenna, etc. However, the use of microstrip line transmission also has the disadvantages of large loss of microstrip line, crosstalk caused by easy leakage of electromagnetic energy, low Q value, difficulty in fine adjustment, and small power capacity.

In the process of using microstrip line transmission, the guided electromagnetic wave on the microstrip line continuously radiates energy along the axial direction of the microstrip line to generate leakage waves, wherein the electromagnetic wave leakage has two forms: surface wave form 5 and spatial wave form 4 ,as shown in picture 2. It is known that there is a leakage main mode in the high frequency band of the microstrip line. This leakage main mode leaks electromagnetic wave energy outward in the form of surface waves. In the low frequency band, each higher order mode of the microstrip line is in the form of spatial wave. External leakage of electromagnetic wave energy. Whether it is surface wave leakage or space wave leakage, these leakage waves are harmful in integrated circuits, which not only bring about a drop in transmission power, but also cause leakage of electromagnetic energy to other surrounding circuits. The overall performance of the system is degraded, so it needs to be suppressed.

In the prior art, a method for suppressing leakage of a microstrip main mode is mainly to apply a thin dielectric layer having a sufficiently large dielectric constant on the microstrip line; however, for the suppression of high order mode leakage of the microstrip line, there is no What is a simple and effective method. This is mainly due to the difference in the physical mechanism of the leakage of the main mode of the microstrip line and the leakage of the high-order mode. The spatial wave leakage of the higher-order mode of the microstrip line is hardly suppressed.

 [Summary of the Invention]

The object of the present invention is to overcome the defects of the spatial wave leakage of the high-order mode of the microstrip line in the prior art, and provide a microstrip line based on a metamaterial, which can effectively suppress the leakage of the space wave and solve the problem between the microstrip lines. The problem of electromagnetic wave crosstalk.

In order to solve the above technical problem, a technical solution adopted by the present invention is to provide a microstrip line including a metal strip, a dielectric substrate and a grounding plate, the microstrip line further comprising a metamaterial film, a metamaterial film and a metal strip It is located on one side of the dielectric substrate and is in close contact with the dielectric substrate, wherein the metamaterial film covers the metal strip, and the ground plate is located on the other side of the dielectric substrate.

Wherein, the metamaterial film is formed by stacking a plurality of metamaterial sheets, and the plurality of metamaterial sheets have the same refractive index distribution.

Each of the metamaterial sheets is composed of a plurality of metamaterial units.

Among them, the metamaterial unit includes an artificial microstructure and a unit substrate to which the artificial microstructure is attached.

Wherein, the artificial microstructure is a planar structure or a three-dimensional structure composed of at least one wire responsive to an electromagnetic field, and the wire is a copper wire or a silver wire.

Wherein, the wire is attached to the unit substrate by etching, electroplating, drilling, photolithography, electron engraving or ion etching.

Among them, the artificial microstructure is any one of a snowflake-shaped or snowflake-shaped derivative.

The unit substrate is made of ceramic material, epoxy resin, polytetrafluoroethylene, FR-4 composite material or F4B composite material.

Wherein, the refractive index distribution in each super-material layer is uniform, and the refractive index has a value ranging from 0 to 1.

Wherein, the refractive index in each super-material layer is 0.7.

The dielectric substrate is formed by splicing a first substrate and a second substrate. The first substrate and the second substrate have different refractive index distributions, and the second substrate is spliced on both sides of the first substrate. The first substrate.

Wherein, the refractive index of the first substrate is smaller than the refractive index of the second substrate.

The material of the first substrate is FR-4.

Wherein, the second substrate is an alumina ceramic material.

Different from the prior art, the beneficial effects of the present invention are that the microstrip line based on the metamaterial can effectively suppress the leakage wave in the form of a space wave of the microstrip line and reduce the electromagnetic wave crosstalk of the adjacent microstrip line. .

 [Description of the Drawings]

1 is a schematic structural view of a microstrip line in the prior art;

2 is a schematic view showing two types of leakage waves of a microstrip line in the prior art;

3 is a schematic structural view of a microstrip line according to a first embodiment of the present invention;

4 is a schematic structural view of a metamaterial film according to a first embodiment of the present invention;

Figure 5 is a schematic structural view of a metamaterial unit according to a first embodiment of the present invention;

6 is a schematic structural view of a microstrip line according to a second embodiment of the present invention;

Figure 7 is a schematic structural view of a microstrip line according to a third embodiment of the present invention;

8 is a schematic structural view of a microstrip line according to a fourth embodiment of the present invention;

9 is a schematic structural view of a microstrip line according to a fifth embodiment of the present invention;

Figure 10 is a schematic view showing the structure of a microstrip line according to a sixth embodiment of the present invention.

 【detailed description】

The present invention will be further described in detail below with reference to the embodiments and drawings, but the embodiments of the present invention are not limited thereto.

As shown in FIG. 3, the present invention is based on the structure diagram of a micro-belt line of a metamaterial. The microstrip line includes a metal strip 10, a grounding plate 20, and a dielectric substrate 30, wherein the metal strip 10 and the grounding plate 20 are respectively located on the dielectric substrate 30. On both sides, the metal strip 10 is generally disposed on the dielectric substrate 30 by means of circuit printing. In the preferred embodiment of the present invention, a surface of the dielectric substrate on the same side of the metal strip 10 is coated with a layer of metamaterial 40, and The metamaterial film 40 completely covers the metal strip 10.

In the present invention, both the metal strip 10 and the grounding plate 20 are made of the same metal, and copper is generally used.

In order to suppress the leakage of the spatial wave generated during the electromagnetic wave transmission of the metal strip 10, the super-material film 40 is used as the cover metal strip 10, thereby reducing electromagnetic wave crosstalk between adjacent microstrip lines.

The metamaterial film 40 is comprised of a plurality of metamaterial sheets 401, each of which is comprised of a plurality of metamaterial units 50 comprising an artificial microstructure 502 and a unit for attachment of the artificial microstructure 502 Substrate 501.

The plurality of metamaterial sheets 401 are a plurality of metamaterial sheets having the same refractive index distribution.

The refractive index distribution in each metamaterial sheet 401 is uniform, but the refractive index ranges between 0 and 1, since this refractive index range is the refractive index range of the medium in which the invisibility cloak is made, using such a metamaterial film. Covering the metal strip 10 can effectively suppress the leakage of the spatial wave form of the microstrip line and reduce the electromagnetic wave crosstalk of the adjacent microstrip line. In a preferred embodiment of the invention, the refractive index in each of the metamaterial sheets 401 has a value of 0.7.

In order to achieve a change in the refractive index shown in FIG. 3 for each of the metamaterial sheets 401 of the metamaterial film 40, the topology, geometry, and unit cell 501 of the artificial microstructure 502 can be theoretically and practically demonstrated. The distribution of the unit substrate 501 is made of a dielectric insulating material, which may be a ceramic material, a polymer material, a ferroelectric material, a ferrite material, a ferromagnetic material, etc., and the polymer material may be, for example, an epoxy resin or a poly Tetrafluoroethylene. The artificial microstructure 502 is a metal wire which is attached to the unit substrate 501 in a certain geometric shape and is responsive to electromagnetic waves. The metal wire may be a copper wire or a silver wire having a cylindrical or flat shape, and is generally made of copper because The copper wire is relatively cheap. Of course, the cross section of the metal wire can also be other shapes. The metal wire is attached to the unit substrate 501 by etching, electroplating, drilling, photolithography, electron engraving or ion etching, and each of the super material sheets. Layer 401 is comprised of a plurality of metamaterial units 50, each having an artificial microstructure 502, each of which reacts to electromagnetic waves passing therethrough, thereby affecting the transmission of electromagnetic waves therein, each The size of the metamaterial unit 50 depends on the electromagnetic wave that needs to be responsive, typically one tenth of the wavelength of the electromagnetic wave that is required to respond, otherwise the arrangement of the metamaterial unit 50 containing the artificial microstructure 502 in space cannot be viewed in space. For continuous.

In the case of the selection of the unit substrate 501, by adjusting the shape and size of the artificial microstructure 502 and its spatial distribution on the unit substrate 501, the equivalent dielectric constant and equivalent of each place on the metamaterial can be adjusted. The magnetic permeability in turn changes the equivalent refractive index throughout the metamaterial. When the artificial microstructure 502 adopts the same geometry, the larger the size of the artificial microstructure at a certain place, the larger the equivalent dielectric constant and the larger the refractive index.

The pattern of the artificial microstructure 502 used in this embodiment is a snowflake-shaped derivative pattern. As can be seen from FIG. 4 and FIG. 5, the size of the snowflake artificial microstructure 502 can be determined according to a specific application.

Example 2

As shown in FIG. 6, a microstrip line includes a metal strip 100, a dielectric substrate, and a ground plate 200. The dielectric substrate is formed by splicing the first substrate 400 and the second substrate 300, and the first substrate 400 and the second substrate The substrate 300 has different refractive index distributions, and the second substrate 300 is spliced on both sides of the first substrate 400. The first substrate 400 is disposed directly under the metal strip 100, and the ground plate 200 is directly under the dielectric substrate.

The material of the first substrate 400 is FR-4.

The second substrate 300 is an alumina ceramic material.

The refractive index of the first substrate 400 is smaller than the refractive index of the second substrate 300.

The refractive range of the first substrate 400 is 2 to 10.

The second substrate 300 has a refractive range of 10 to 20.

In a preferred embodiment of the invention, the first substrate 400 has a refraction of 4.5.

In a preferred embodiment of the invention, the second substrate 300 has a refraction of 12.

Example 3

According to another embodiment of the present invention, as shown in FIG. 7, a suspended microstrip line is different from Embodiment 2 in that the grounding plate 200 is suspended directly below the dielectric substrate and is not in close contact with the medium. The substrate was the same as in the second embodiment.

Example 4

As shown in FIG. 8 , it is an inverted microstrip line, which is different from Embodiment 3 in that the metal strip 100 is located on the same side as the ground plane 200 and is in close contact with the dielectric substrate, and the others are the same as in Embodiment 3. .

Example 5

As shown in FIG. 9 , it is a coupled microstrip line, which is different from Embodiment 2 in that two identical metal strips 100 are disposed on one side of the dielectric substrate, and a grounding plate 200 is disposed on the other side. The refractive index distribution of the dielectric substrate under each of the metal strips 100 is the same as that of the second embodiment.

Example 6

As shown in FIG. 10, it is a microstrip line. The microstrip line includes a metal strip 610, a dielectric substrate, and a grounding plate 620. The microstrip line further includes a metamaterial film 650. The metamaterial film 650 and the metal strip 610 are located on one side of the dielectric substrate and are in close contact with the dielectric substrate. Among them, the metamaterial film 650 covers the metal strip 610. The first substrate 640 and the second substrate 630 have different refractive index distributions, and the second substrate 630 is spliced on both sides of the first substrate 640, wherein the metal strip A first substrate 640 is disposed directly below the 610, and the ground plate 620 is located on the other side of the dielectric substrate.

Among them, the metamaterial film 650 is, for example, the metamaterial film 40 described in the first embodiment. In other embodiments, the dielectric substrate, metal strip 610, and ground plane are, for example, described in Examples 2-5.

Different from the prior art, the beneficial effects of the present invention are that the microstrip line based on the metamaterial can effectively suppress the leakage wave in the form of a space wave of the microstrip line and reduce the electromagnetic wave crosstalk of the adjacent microstrip line. .

The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and modifications made without departing from the spirit and scope of the present invention. Simplifications should all be equivalent replacements and are included in the scope of the present invention.

Claims (14)

1. A microstrip line comprising a metal strip, a dielectric substrate, and a grounding plate, wherein the microstrip line further comprises a metamaterial film, and the metamaterial film and the metal strip are located on the dielectric substrate One side, and both are in close contact with the dielectric substrate, wherein the metamaterial film covers the metal strip, and the ground plate is located on the other side of the dielectric substrate.
2. The microstrip line according to claim 1, wherein the metamaterial film is formed by stacking a plurality of metamaterial sheets, and the plurality of metamaterial sheets have the same refractive index distribution.
3. The microstrip line according to claim 2, wherein each of the metamaterial sheets is composed of a plurality of metamaterial units.
4. The microstrip line according to claim 3, wherein the metamaterial unit comprises an artificial microstructure and a unit substrate to which the artificial microstructure is attached.
5. The microstrip line according to claim 4, wherein the artificial microstructure is a planar structure or a three-dimensional structure composed of at least one wire responsive to an electromagnetic field, the wire being a copper wire or a silver wire.
6. The microstrip line according to claim 5, wherein the wire is attached to the unit substrate by etching, plating, drilling, photolithography, electron engraving or ion etching.
7. The microstrip line according to claim 5, wherein the artificial microstructure is any one of a snowflake-shaped or snowflake-shaped derivative.
8. The microstrip line according to claim 4, wherein the unit substrate is made of a ceramic material, an epoxy resin, a polytetrafluoroethylene, an FR-4 composite material or an F4B composite material.
9. The microstrip line according to claim 2, wherein the refractive index distribution in each of the metamaterial sheets is uniform, and the refractive index has a value ranging from 0 to 1.
10. The microstrip line according to claim 9, wherein the refractive index in each of the metamaterial sheets is 0.7.
11. The microstrip line according to claim 1, wherein the dielectric substrate is formed by splicing a first substrate and a second substrate, the first substrate and the second substrate having different refractive index distributions, and the first substrate A second substrate is spliced on both sides, wherein the first substrate is disposed directly under the metal strip.
12. The microstrip line according to claim 11, wherein the refractive index of the first substrate is smaller than the refractive index of the second substrate.
13. The microstrip line according to claim 11, wherein the material of the first substrate is FR-4.
14. The microstrip line according to claim 11, wherein the second substrate is an alumina ceramic material.

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