CN102956975B - a horn antenna - Google Patents

Abstract

The invention discloses a horn antenna, which includes an antenna body and a metamaterial close to the aperture surface of the antenna body, the central axis of the antenna body passes through the center point of the metamaterial; the metamaterial includes a base material and a metamaterial. A plurality of artificial metal microstructures periodically arranged on the substrate, the refractive index of the metamaterial is distributed in a circle, and the refractive index at the center of the circle is the smallest. With the increase of the radius, the refractive index gradually increases, the same The refractive index is the same at the radius. The invention expands the radiation angle of the antenna body by adding metamaterials with divergence function on the existing antenna body.

Description

a horn antenna

technical field

The invention relates to the technical field of antennas, in particular to a horn antenna.

Background technique

Horn antenna refers to the antenna whose waveguide terminal is opened into a horn shape, and its name comes from its shape. The horn antenna has a simple structure and is easy to control the pattern, which can be used as a directional antenna or as a feed source.

The radiation angle of the horn antenna is determined by the size of the horn mouth. When the radiation angle needs to be enlarged, the size of the horn mouth needs to be enlarged accordingly. Under the current trend of pursuing miniaturization and high gain of various electronic components, how to expand the radiation range of the horn antenna without expanding the size of the horn antenna has become an urgent problem to be solved.

Contents of the invention

The technical problem to be solved by the present invention is to propose a horn antenna with a wide radiation range, freely controllable radiation angle and small size in view of the above-mentioned deficiencies in the prior art.

The present invention solves the technical problem, and the technical solution adopted is to propose a horn antenna, which includes: an antenna body and a metamaterial close to the aperture surface of the antenna body, and the central axis of the antenna body passes through the metamaterial The center point of the metamaterial; the metamaterial includes a substrate and a plurality of artificial metal microstructures periodically arranged on the substrate, the refractive index of the metamaterial is circularly distributed, and the refractive index at the center of the circle is the smallest. As the radius increases, the refractive index increases gradually, and the refractive index at the same radius is the same.

Further, the refractive index distribution of the metamaterial satisfies the law:

$\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; *</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; ss</span>}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; r</span>}}{\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}}<span\; class="notranslate">\; -</span>\sqrt{{<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; r</span>}}{\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; r</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; -</span>\sqrt{{\mathrm{<span\; class="notranslate">\; ss</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; r</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; )</span>$

Wherein, r is the radius value with identical refractive index; D is the thickness of metamaterial; ss is the distance from the center point of metamaterial by the point source equivalent of described antenna body; n (0) is described metamaterial center point The refractive index value of ; θ is the exit angle of the electromagnetic wave diverged by the metamaterial.

Further, the shape of the aperture surface of the antenna body is circular, rectangular or trapezoidal.

Further, the plurality of artificial metal microstructures have the same geometric shape, and the plurality of artificial metal microstructures are distributed circularly on the substrate, and the size of the artificial metal microstructure at the center of the circle is the smallest. The size of the artificial metal microstructure increases, and the size of the artificial metal microstructure at the same radius is the same.

Further, the geometric shape of the artificial metal microstructure is "I" shape, including a vertical first metal branch and a second metal branch located at both ends of the first metal branch and perpendicular to the first metal branch .

Further, the geometric shape further includes a third metal branch located at both ends of the second metal branch and perpendicular to the second metal branch.

Further, the geometric shape of the artificial metal microstructure is a plane snowflake, including two first metal branches perpendicular to each other and a second metal branch located at both ends of the first metal branch and perpendicular to the first metal branch. branch.

Further, the substrate is a polymer material, a ceramic material, a ferroelectric material, a ferrite material or a ferromagnetic material.

Further, the base material is FR4 material or F4B material.

Further, the artificial metal microstructure is periodically arranged on the substrate by etching, electroplating, drilling, photolithography, electron etching or ion etching.

The invention expands the radiation angle of the antenna body by adding metamaterials with divergence function on the existing antenna body.

Description of drawings

Figure 1 is a schematic diagram of the three-dimensional structure of the basic unit constituting the metamaterial;

Fig. 2 is the structural representation of a kind of horn antenna of the present invention;

3 is a schematic diagram of a three-dimensional structure of a metamaterial in a horn antenna of the present invention;

Fig. 4 is a schematic diagram of calculating the refractive index distribution on the longitudinal section of the metamaterial on the horn antenna of the present invention;

Fig. 5 is a cross-sectional schematic diagram of a metamaterial when the shape of the antenna body aperture surface of the horn antenna is rectangular;

Fig. 6 is the geometric topological pattern of the artificial metal microstructure of the first preferred embodiment that can respond to electromagnetic waves to change the refractive index of the basic unit of the metamaterial;

Figure 6a is a derivative pattern of the geometric topological pattern of the artificial metal microstructure in Figure 6;

Fig. 7 is the geometric topological pattern of the artificial metal microstructure that can respond to electromagnetic waves to change the refractive index of the basic unit of the metamaterial in the second preferred embodiment;

Fig. 7a is a derivative pattern of the geometric topological pattern of the artificial metal microstructure in Fig. 7.

Detailed ways

Light, as a kind of electromagnetic wave, when it passes through glass, because the wavelength of light is much larger than the size of atoms, we can use the overall parameters of the glass, such as the refractive index, rather than the detailed parameters of the atoms that make up the glass to describe The response of glass to light. Correspondingly, when studying the response of materials to other electromagnetic waves, the response of any structure in the material whose scale is much smaller than the wavelength of the electromagnetic wave to electromagnetic waves can also be described by the overall parameters of the material, such as the dielectric constant ε and magnetic permeability μ. By designing the structure of each point of the material, the dielectric constant and magnetic permeability of each point of the material are the same or different, so that the overall dielectric constant and magnetic permeability of the material are arranged in a certain order, and the regularly arranged magnetic permeability and magnetic permeability The electrical constant can make the material have a macroscopic response to electromagnetic waves, such as converging electromagnetic waves and diverging electromagnetic waves. Such materials with regularly arranged magnetic permeability and permittivity are called metamaterials.

As shown in FIG. 1 , FIG. 1 is a schematic diagram of a three-dimensional structure of a basic unit constituting a metamaterial. The basic unit of a metamaterial includes an artificial microstructure 1 and a substrate 2 to which the artificial microstructure is attached. In the present invention, the artificial microstructure is an artificial metal microstructure, and the artificial metal microstructure has a planar or three-dimensional topological structure that can respond to the electric field and/or magnetic field of the incident electromagnetic wave, and changes the performance of the artificial metal microstructure on each metamaterial basic unit. The pattern and/or size can change the response of each metamaterial elementary unit to incident electromagnetic waves. Multiple basic units of metamaterials can be arranged according to certain rules to make metamaterials have a macroscopic response to electromagnetic waves. Since the overall metamaterial needs to have a macroscopic electromagnetic response to the incident electromagnetic wave, the response of each metamaterial basic unit to the incident electromagnetic wave must form a continuous response, which requires that the size of each metamaterial basic unit be one-tenth to one-fifth of the incident electromagnetic wave One, preferably one-tenth of the incident electromagnetic wave. In the description in this paragraph, we artificially divide the metamaterial as a whole into multiple metamaterial basic units, but it should be known that this division method is only for the convenience of description, and it should not be regarded as a metamaterial spliced or assembled by multiple metamaterial basic units. In practical applications, metamaterials can be formed by periodically arranging artificial metal microstructures on a substrate, which is simple in process and low in cost. The periodic arrangement means that the artificial metal microstructures on the basic units of the above-mentioned metamaterials that we artificially divide can produce continuous electromagnetic responses to incident electromagnetic waves.

Please refer to FIG. 2 , which is a schematic structural diagram of the horn antenna of the present invention. In FIG. 2 , the horn antenna includes an antenna body 100 and a metamaterial 300 closely attached to the aperture surface of the antenna body. The axis of symmetry of the antenna body passes through the central point of the metamaterial.

Please refer to FIG. 3 . FIG. 3 is a three-dimensional structural diagram of the metamaterial in the horn antenna of the present invention. In FIG. 3 , a metamaterial 300 includes a substrate 301 and a plurality of artificial metal microstructures 302 periodically arranged on the substrate. In this embodiment, in order to facilitate packaging and protect the artificial metal microstructures, a covering layer 303 with the same thickness and material as the substrate 301 is also covered on the plurality of artificial metal microstructures 302 . A plurality of artificial metal microstructures 302 have the same geometric shape, and the plurality of artificial metal microstructures 302 are distributed circularly on the substrate 301, and the size of the artificial metal microstructure at the center of the circle, that is, the center of the metamaterial, is the smallest. As the radius increases, the size of the artificial metal microstructure increases, and the size of the artificial metal microstructure at the same radius is the same.

When the metamaterial 300 is cut from the middle, the refractive index distribution on the longitudinal section of the metamaterial 300 is rotated once to obtain the overall refractive index distribution of the metamaterial 300 . We can know the overall refractive index distribution of the metamaterial 300 through the refractive index distribution on the longitudinal section of the metamaterial 300 . As shown in FIG. 4 , FIG. 4 is a schematic diagram for calculating the refractive index distribution on the longitudinal section of the metamaterial on the horn antenna of the present invention. In Figure 4, the antenna body is equivalent to a point source. The spherical wave emitted by the point source is diverged after passing through the metamaterial, and the outgoing angle of the diverged electromagnetic wave is θ. After calculation, we can get the distribution relationship of the refractive index of the metamaterial as:

$\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; *</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; ss</span>}<span\; class="notranslate">\; +</span>\frac{\mathrm{<span\; class="notranslate">\; r</span>}}{\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}}<span\; class="notranslate">\; -</span>\sqrt{{<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; r</span>}}{\mathrm{<span\; class="notranslate">\; sin</span>}\mathrm{<span\; class="notranslate">\; \&theta;</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; r</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; -</span>\sqrt{{\mathrm{<span\; class="notranslate">\; ss</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; r</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; )</span>$

Among them, r is the radius value of the artificial metal microstructure with the same refractive index from the center point of the metamaterial, that is, the distance from the central axis on the longitudinal section of the metamaterial in Figure 4; d is the thickness of the metamaterial; ss is the antenna The distance between the equivalent point source of the body and the center point of the metamaterial; n(0) is the refractive index value of the center point of the metamaterial, that is, the minimum refractive index value of the metamaterial; θ is the exit angle of the electromagnetic wave diverged by the metamaterial .

Furthermore, since n(0) is the minimum refractive index of the metamaterial, when the difference between n(0) and the free space refractive index is large, the electromagnetic waves incident on the metamaterial in free space will be partially reflected. In this case, an impedance matching layer can also be added on both sides of the metamaterial to reduce reflection and increase gain.

At the same time, when the aperture shape of the horn body of the horn antenna of the present invention changes, it is only necessary to cut out the required shape on the basis of the original circular design. As shown in Figure 5, in the figure, the dotted line part is the circular distribution of the refractive index and the artificial metal microstructure in the initial design. When the shape of the aperture surface of the antenna body is rectangular, the solid line part is directly intercepted on the basis of the circular distribution. The rectangle is enough.

There are many geometric shapes of the artificial metal microstructures that meet the requirements of the above-mentioned refractive index distribution of metamaterials, but all of them are geometric shapes that can respond to incident electromagnetic waves. The most typical one is the "I" shaped artificial metal microstructure. Several artificial metal microstructure geometries are described in detail below. The size of the artificial metal microstructure corresponding to the refractive index of each point on the metamaterial can be obtained through computer simulation or manual calculation.

As shown in FIG. 6 , FIG. 6 is a geometric topological pattern of the artificial metal microstructure of the first preferred embodiment that can respond to electromagnetic waves to change the refractive index of the basic unit of the metamaterial. In Fig. 6, the artificial metal microstructure is in the shape of "I", including a vertical first metal branch 1021 and a second metal branch 1022 perpendicular to the first metal branch 1021 and located at both ends of the first metal branch, and Fig. 6a is a diagram The derivative pattern of the artificial metal microstructure geometric topological pattern in 6, which not only includes the first metal branch 1021 and the second metal branch 1022, but also has a third metal branch 1023 vertically arranged at both ends of each second metal branch.

Fig. 7 is a geometric topological pattern of an artificial metal microstructure capable of changing the refractive index of a basic unit of a metamaterial in response to electromagnetic waves in a second preferred embodiment. In Fig. 7, the artificial metal microstructure is in the shape of a plane snowflake, including first metal branches 1021' perpendicular to each other and second metal branches 1022' vertically arranged at both ends of the two first metal branches 1021'; Fig. 7a is Fig. 7 The derivative pattern of the geometric topological pattern of the artificial metal microstructure shown not only includes two first metal branches 1021', four second metal branches 1022', but also a third metal branch 1023 vertically arranged at both ends of the four second metal branches '. Preferably, the first metal branches 1021' have equal lengths and intersect perpendicularly to the midpoint, the second metal branches 1022' have equal lengths and the midpoint is at the end of the first metal branch, the third metal branches 1023' have the same length and the midpoint is at the second End points of metal branches; the arrangement of the above metal branches makes the artificial metal microstructure isotropic, that is, the artificial metal microstructure can be overlapped with the original artificial metal microstructure by rotating the artificial metal microstructure by 90° in any direction in the plane to which the artificial metal microstructure belongs. The use of isotropic artificial metal microstructures can simplify design and reduce interference.

In the present invention, the substrate can be made of ceramics, polymer materials, ferroelectric materials, ferrite materials or ferromagnetic materials. For example, polytetrafluoroethylene, epoxy resin, FR4, F4b and other polymer materials. Artificial metal microstructures are attached to substrates by methods such as etching, electroplating, drilling, photolithography, electron etching, or ion etching. Among them, etching is a better manufacturing process. After designing a suitable planar pattern of artificial metal microstructures, first attach a piece of metal foil to the substrate as a whole, and then pass through the etching equipment, using solvent and metal The chemical reaction removes the foil part outside the preset pattern of the artificial metal microstructure, and the remaining artificial metal microstructure arranged in a periodic array can be obtained.

Embodiments of the present invention have been described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementations, and the above-mentioned specific implementations are only illustrative, rather than restrictive, and those of ordinary skill in the art will Under the enlightenment of the present invention, many forms can also be made without departing from the gist of the present invention and the protection scope of the claims, and these all belong to the protection of the present invention.

Claims (9)

1. a horn antenna, is characterized in that: comprise antenna body and be close to the Meta Materials on the bore face of antenna body, and the central axis of described antenna body passes the central point of described Meta Materials; Described Meta Materials comprises base material and cycle and is arranged in multiple artificial metal's micro-structurals on base material, the rounded distribution of described Meta Materials refractive index everywhere, the refractive index of circle centre position is minimum, along with the increase of radius, refractive index increases gradually, the refractive index at same radius place is identical, and the refraction index profile of described Meta Materials meets rule:

$n\left(r\right)=n\left(0\right)+\frac{1}{d}*(\mathrm{ss}+\frac{r}{\sin \mathrm{\&theta;}}-\sqrt{{\left(\frac{r}{\sin \mathrm{\&theta;}}\right)}^2-r^2}-\sqrt{{\mathrm{ss}}^2+r^2})$

Wherein, r is the radius value with identical refractive index; D is the thickness of Meta Materials; Ss is by the distance of the some spacing Meta Materials central point of described antenna body equivalence; N (0) is the refractive index value of described Meta Materials central point; θ is the electromagnetic angle of emergence after being dispersed by Meta Materials.

2. horn antenna as claimed in claim 1, is characterized in that: the bore face shape of described antenna body is circular, rectangle or trapezoidal.

3. horn antenna as claimed in claim 1, it is characterized in that: described multiple artificial metal's micro-structural has identical geometry, the rounded distribution on the substrate of described multiple artificial metal's micro-structural, artificial metal's microstructure size of circle centre position is minimum, along with the increase of radius, the size of artificial metal's micro-structural increases, and artificial metal's microstructure size at same radius place is identical.

4. horn antenna as claimed in claim 3, it is characterized in that: the geometry of described artificial metal's micro-structural is " work " font, comprise the first vertical metal branch and be positioned at described first metal branch two ends and perpendicular to the second metal branch of described first metal branch.

5. horn antenna as claimed in claim 4, is characterized in that: described geometry also comprises and is positioned at described second metal branch two ends and perpendicular to the 3rd metal branch of described second metal branch.

6. horn antenna as claimed in claim 3, it is characterized in that: the geometry of described artificial metal's micro-structural is plane snowflake type, comprise orthogonal two the first metal branch and be positioned at described first metal branch two ends and perpendicular to the second metal branch of described first metal branch.

7. horn antenna as claimed in claim 1, is characterized in that: described base material is macromolecular material, ceramic material, ferroelectric material, ferrite material or ferromagnetic material.

8. horn antenna as claimed in claim 7, is characterized in that: described base material is FR4 material or F4B material.

9. horn antenna as claimed in claim 1, is characterized in that: described artificial metal's micro-structural is arranged on described base material by etching, electroplating, bore quarter, photoetching, electronics quarter or ion cycle of carving.