CN102110890B - High-gain horn antenna based on non-uniform medium - Google Patents

Abstract

A kind of high-gain horn antenna based on inhomogeneous medium is made as follows: (1) determine the center frequency f of antenna work; (2) design the common horn antenna that works at this center frequency according to the general design method of horn antenna, the antenna's The diameter of the H surface is a, the diameter of the E surface is b, and the length of the horn is h; (3) determine the refractive index distribution n(x, y) of the heterogeneous medium placed on the horn mouth surface; (4) use the "I" font The sub-wavelength artificial structure material constructs a heterogeneous medium whose refractive index is distributed according to n(x, y), and the structure size of the I-shaped sub-wavelength artificial structure material unit corresponding to each refractive index is calculated by means of finite element software simulation.

Description

A kind of high-gain horn antenna based on non-uniform dielectric

Technical field

The present invention is designed into a kind of horn antenna, particularly a kind of high-gain horn antenna based on non-uniform dielectric.

Background technology

Horn antenna is a kind of directional antenna, and it can regard the waveguide of opening as.The function of loudspeaker is to produce uniform phase front at the bore larger than waveguide, thereby obtains higher directionality.Because its design, easy to manufacture and cost is all lower, horn antenna has widely purposes in real life.

What limit the horn antenna directivity mainly is the inconsistency of phase place on the loudspeaker actinal surface.When electromagnetic wave entered loudspeaker throat and arrives the loudspeaker actinal surface from waveguide, electromagnetic corrugated became sphere by the plane, no longer equated in the power on phase place of magnetic wave of loudspeaker actinal surface.In order to reduce the inconsistency of phase place on the actinal surface, the means that often adopt are to change the subtended angle of loudspeaker or the length of loudspeaker, but adopt above-mentioned means can only reduce phase difference, can not fundamentally eliminate the inconsistent harmful effect of phase place.

Summary of the invention

The technical problem to be solved in the present invention is: overcome the upper mutually inconsistent shortcoming of existing common horn antenna loudspeaker actinal surface, a kind of high-gain horn antenna based on non-uniform dielectric is provided, adopt non-uniform dielectric to eliminate phasic difference, the gain that has improved horn antenna.

Technical solution of the present invention: based on the high-gain horn antenna of non-uniform dielectric, making step is as follows:

(1) determines the centre frequency f of antenna work, centre frequency according to antenna work is designed a horn antenna that is operated in this frequency range according to the method for designing of common horn antenna, the H face bore of described horn antenna is a, and E face bore is b, and horn length is h;

(2) increase one deck non-uniform dielectric at the loudspeaker actinal surface of horn antenna, according to the thickness d of non-uniform dielectric and the non-uniform dielectric refractive index n at origin of coordinates place ₀, obtain the refraction index profile n (x, y) of the non-uniform dielectric that places the loudspeaker actinal surface,

X wherein, y represent the non-uniform dielectric each point take the Antenna aperture center as the origin of coordinates, the coordinate in the coordinate system of setting up take the horn antenna radiation direction as x axle forward;

(3) change into a plurality of cubic units that the length of side is l with non-uniform dielectric is discrete, obtain the refractive index n (m, n) of each cubic units by the formula in the step (2), wherein (m, n) is the numbering of unit;

(4) FEM (finite element) model of foundation " worker " font sub-wavelength artificial structure material, the equivalent refractive index of employing Finite Element Calculating material, the structural parameters a of change material ₀, a ₀Be the length of side of " worker " shape metal structure in " worker " font structure, simulation calculation goes out different length of side a ₀The equivalent refractive index n of structural correspondence;

(5) by a that obtains in the step (4) ₀Obtain the physical dimension of each junior unit in the step (3) with the relation of n, with each unit of this dimensioned, again all unit combination can be obtained the non-uniform dielectric that needs.

N in the described step (2) ₀Value should determine that according to minimum and the largest refractive index of the described artificial structure's material in back minimum and the largest refractive index of establishing " worker " font artificial structure material are n _Min, n _Max, n then ₀Satisfy: $n_{\min }+\frac{\sqrt{h^2+\frac{b^2}{4}}-h}{d}<{\mathrm{<figure-callout\; id="0"\; label="n"\; filenames="HDA0000046613940000012.png"\; state="\{\{state\}\}">n</figure-callout>}}_0<n_{\max }.$

The length of side l of the cubic units in the described step (3) is less than or equal to 1/10th of antenna operation wavelength.

All regard each cubic units after the non-uniform dielectric discretization as uniform dielectric in the described step (3), because the size of each unit is less than 1/10th wavelength, index step changes and can ignore between unit and the unit, brings the center point coordinate of each unit into formula

In can calculate the refractive index of this unit.

" worker " font sub-wavelength artificial structure material in the described step (4) is that the cubic units of l forms by the length of side, and each unit is comprised of three parts: thickness is h ₀FR-4 substrate, the thickness that etches in substrate be " worker " font copper metal film of 0.017mm and the medium that wraps up them, wherein the vertical edge width in the middle of " worker " font is w ₁, the horizontal edge width on both sides is w up and down ₂, the dielectric constant of medium is ε ₀

Described medium be air or silicon, the dielectric constant of the medium of selecting is larger, the equivalent refractive index that obtains is also larger.

Utilize the equivalent refractive index implementation of Finite Element Calculating material as follows in the described step (4): to adopt the commercial finite element software of CST or HFSS, set up the model of element of " worker " font artificial structure material, threedimensional model is comprised of three parts: thickness is h ₀FR-4 substrate, the thickness that etches in substrate be " worker " font copper metal film of 0.017mm and the medium that wraps up them, wherein to be the vertical edge width in the middle of the l I shape be w to unit length and width height ₁, the horizontal edge width on both sides is w up and down ₂, the dielectric constant of medium is ε ₀The front of model is " worker " font copper film, and the model side is set to periodic boundary condition, and front and back arranges respectively two ripple ports.The frequency range of emulation should comprise the operating frequency of antenna, obtains the scattering parameter of model by simulation calculation, calculates the equivalent refractive index of material according to the scattering parameter method of inversion again.

Each unit of processing adopts the processing method of pcb board in the described step (5), the substrate that is positioned at all unit of same layer can share a large FR-4 sheet material, just etch the I shape metal structure of corresponding size at the diverse location place of sheet material, fill the medium of selecting between every one deck FR-4 sheet material.

The present invention's advantage compared with prior art is:

(1) the present invention adds the last layer non-uniform dielectric at the loudspeaker actinal surface, has fundamentally eliminated the position phase inconsistency on the actinal surface, and the gain that has improved horn antenna can be used for designing the horn antenna of high-gain.

(2) high-gain horn antenna of the present invention is compared with the common horn antenna with identical gain, and length and the bore of loudspeaker are less, are convenient to the miniaturization of device.

(3) " worker " font artificial structure material of the present invention's employing can obtain various refractive indexes easily by the adjustment structure parameter, and the non-constant width of the frequency band of this kind structural material, loss is also little, can go out " worker " font metal structure by direct etching on FR-4 sheet material, and is easy to process.

Description of drawings

Fig. 1 is antenna structure view of the present invention.Left figure is H face view, and right figure is E face view.Curve in the loudspeaker represents the corrugated, can find out after spherical wave is by non-uniform dielectric to have become plane wave from left figure;

Fig. 2 is the non-uniform dielectric discretization schematic diagram among the present invention.Right figure shown discrete after to the mode of each element number, non-uniform dielectric has been separated into 45X35 junior unit, each unit all is one and longly is the cube of l, is comprised of " worker " font sub-wavelength artificial structure material;

Fig. 3 is " worker " font sub-wavelength artificial structure material cell model schematic diagram among the present invention.Yl moiety is copper film among the figure, and purple partly is medium substrate, and translucent blue portion is the medium of lapping;

Fig. 4 is the structural representation of the every layer of material among the present invention.Left figure is the overall distribution situation of every one deck unit, and right figure is the schematic diagram of unit.

Embodiment

As shown in Figure 1, the high-gain horn antenna specific implementation process based on non-uniform dielectric of the present invention is as follows:

(1) the work centre frequency of choosing antenna is 15GHz, determines the H face bore a=90mm of horn antenna according to the method for designing of conventional horn antenna, and E face bore is b=69mm, horn length h=115mm.

(2) get the thickness d=8mm of medium, the refractive index of medium at origin of coordinates place is 2.2, and this moment, the refractive index at origin of coordinates place satisfied Then the refraction index profile of non-uniform dielectric is Calculate as can be known only skewness in the H face of medium by formula, and maximum in the refractive index of initial point, be 2.2, minimum in the refractive index at edge, be 1.14.

(3) because the operation wavelength of antenna is 20mm, non-uniform dielectric can be dispersed and change into the cubic units that the length of side is l=2mm, as shown in Figure 2.Each unit is all regarded uniform medium as, and its refractive index is refractive index corresponding to unit center point.Because the distribution of refractive index is only relevant with the y coordinate figure of unit center point, so be the same in the four-layer structure of x direction, only need to consider one deck structure.45 * 35 unit are all arranged on every one deck, be numbered according to as shown in Figure 2 method, then the refractive index of each unit is:

$n(m,n)=\mathrm{2,2}-\frac{\sqrt{13225+{(2m-46)}^2}-115}{8}$

In the formula, (m, n) is the numbering of unit.

(4) FEM (finite element) model of foundation " worker " font sub-wavelength artificial structure material as shown in Figure 3 in order to reduce cost, selects circuit board medium FR-4 commonly used as the substrate of material, searches the specification of this medium and determines that substrate is h in the model ₀The FR-4 of=0.2026mm, its dielectric constant are 3.85+i0.02.Given " worker " font copper film vertical edge width is w ₁=0.3mm, horizontal edge width are w ₂=0.2mm is to guarantee a ₀The variations in refractive index of artificial structure's material comprises the zone of 1.14-2.2 during variation.In the CST simulation software, utilize periodic boundary condition to obtain the scattering parameter of material, obtained again the equivalent refractive index of sub-wavelength artificial structure material by the scattering parameter method of inversion, be i.e. every given parameter a ₀, all can obtain one to one equivalent refractive index by the method for FEM (finite element) calculation emulation.Change the structural parameters a of material ₀(a ₀The length of side for " worker " shape metal structure in the I-shaped structure), simulation calculation goes out different length of side a ₀The equivalent refractive index n of structural correspondence, such as a ₀During=1mm, refractive index is about 1.34, a ₀During=1.5mm, refractive index is 1.73, can obtain by that analogy equivalent refractive index about structural parameters a ₀Variation relation.

(5) refractive index in the basis (4) is about a ₀Curved line relation obtain the structural parameters a of the unit that is numbered (m, n) in the heterogeneous material ₀(m, n), so that the refractive index of this unit is n (m, n), all structural parameters of antenna all can obtain.When making material, the substrate of all unit of same layer can be connected together forms a large FR-4 plate.Make-up room only need to etch in position corresponding to each unit accordingly " worker " font structure (as shown in Figure 4), four layers of same sheet material with " worker " font structure is combined to be placed on horn mouth square getting final product in front at last.Spacing during combination between the adjacent panel is l, and the distance of first block of plate and loudspeaker actinal surface is 1/2.

The non-elaborated part of the present invention belongs to techniques well known.

Claims (5)

1. A method for making a high-gain horn antenna based on a heterogeneous medium, characterized in that the steps of making are as follows: (1) Determine the center frequency f of the antenna work, and design a horn antenna working in this frequency band according to the center frequency of the antenna work according to the design method of the ordinary horn antenna. The H-surface aperture of the horn antenna is a, and the E-surface aperture is b, the horn length is h; (2) Add a layer of inhomogeneous medium on the horn surface of the horn antenna, and calculate the inhomogeneous medium placed on the horn surface according to the thickness d of the inhomogeneous medium and the refractive index n ₀ of the inhomogeneous medium at the coordinate origin The refractive index distribution n(x,y) of Among them, x and y represent the coordinates of each point in the heterogeneous medium in the coordinate system established with the center of the antenna aperture as the coordinate origin and the radiation direction of the horn antenna as the positive direction of the x-axis; (3) Discretize the inhomogeneous medium into multiple cubic units with side length l, and calculate the refractive index n(m,n) of each cubic unit by the formula in step (2), where (m,n) is the number of the unit; (4) Establish the finite element model of the "I"-shaped sub-wavelength artificial structure material, calculate the equivalent refractive index of the material by using the finite element method, and change the structural parameter a ₀ of the material, where a ₀ is the "I" in the I-shaped structure The side length of the shaped metal structure is simulated to calculate the equivalent refractive index n corresponding to the structure with different side length a ₀ ; (5) Obtain the structural size of each small unit in step (3) from the relationship between a ₀ and n obtained in step (4), process each unit with this size, and then combine all units to obtain the required non- homogeneous medium; The value of n ₀ in the step (2) is determined according to the minimum and maximum refractive index of the artificial structure material described later, assuming that the minimum refractive index of the "I"-shaped artificial structure material is n _min , and the maximum refractive index is n _max , then n ₀ satisfies: ${\mathrm{no}}_{\min }+\frac{\sqrt{h^2+\frac{b^2}{4}}-h}{d}<{\mathrm{no}}_0<{\mathrm{no}}_{\max };$ The side length l of the cube unit in the step (3) is less than or equal to one tenth of the working wavelength of the antenna. 2. A method for manufacturing a high-gain horn antenna based on a heterogeneous medium according to claim 1, characterized in that: the "I"-shaped sub-wavelength artificial structure material in the step (4) has a side length of 1 Each unit consists of three parts: an FR-4 substrate with a thickness of h ₀ , an "I"-shaped metal copper film with a thickness of 0.017mm etched on the substrate, and a medium that wraps them. The width of the vertical side in the middle of the "I" font is w ₁ , the width of the horizontal side at the upper and lower sides is w ₂ , and the dielectric constant of the medium is ε ₀ . 3. A kind of method for making a high-gain horn antenna based on a heterogeneous medium according to claim 1, characterized in that: said medium is air or silicon, and the dielectric constant of the selected medium is larger, and the obtained equal The effective refractive index is also larger. 4. A method for manufacturing a high-gain horn antenna based on a heterogeneous medium according to claim 1, characterized in that: the calculation of the equivalent refractive index of the material using the finite element method in the step (4) is specifically implemented as follows: using CST or HFSS commercial electromagnetic simulation software, establish the unit model of "I"-shaped artificial structural materials, the front of the model is "I"-shaped copper film, the side of the model is set as periodic boundary conditions, and two waves are set on the front and back respectively. Port, the frequency band of the simulation should include the working frequency of the antenna, the scattering parameters of the model are obtained through simulation calculation, and then the equivalent refractive index of the material is calculated according to the scattering parameter inversion method. 5. A high-gain horn antenna based on a heterogeneous medium according to claim 1, characterized in that: in the step (5), each unit is processed by a PCB board processing method, and all units located on the same layer The base shares a large FR-4 plate, but the I-shaped metal structure of the corresponding size is etched at different positions of the plate, and the selected medium is filled between each layer of FR-4 plate.

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