CN103367926A - Multi-beam antenna design method based on holographic impedance surface - Google Patents

Abstract

The invention provides a multi-beam antenna design method based on a holographic impedance surface. The design method is based on a holographic impedance surface technology. The holographic impedance surface is composed of metal sticking sheet units, and gaps are reserved among the metal sticking sheet units; impedance values of the sticking sheet units are changed through adjustment of the gaps between the metal sticking sheet units; impedance distribution of the antenna surface is determined according to the combination of the impedance values and the principle of an interference pattern in microwave holography; a monopole antenna of omni-directional radiation is modulated by the impedance interference pattern to generate an antenna pattern satisfying design requirements. The design method is suitable for microwave, millimeter wave and terahertz wave bands.

Description

A kind of multi-beam antenna method for designing based on holographic impedance surface

Technical field

The invention belongs to antenna technical field, especially relate to a kind of multi-beam antenna method for designing based on holographic impedance surface.

Background technology

In the microwave and millimeter wave engineering, utilize the plane wave illumination method correlative study such as to measure and extensively admitted.The method of existing generation plane wave illumination also is of a great variety.

The impedance surface modulation technique that is applied in this field all is based on the phase place of coming the adjustment form surface current by surface impedance, thereby reaches the effect that gives off plane wave.

Holographic technique at first was suggested at optical field, once obtained Nobel Prize in physics in 1971.So-called holography refers to the perfect information of amplitude and phase place, and this technology is mainly used in optical imaging field.Contribution in microwave regime is mainly reflected in the design of microwave holography antenna for this technology.Identical with the optical holographic principle, only the object wave in the imaging has been changed into us and wanted the radiated wave of outgoing, we also can be referred to as them the reproduction ripple.Based on the impedance meter surface technology, in conjunction with the microwave holography antenna technology, can design the directed radiation of any wave beam that we want.

Summary of the invention

Technical problem to be solved by this invention is to overcome the deficiencies in the prior art, the present invention proposes a kind of multi-beam antenna method for designing based on holographic impedance surface.This antenna is modulated into directed radiation on certain direction by holographic impedance surface modulation technique with the omnidirectional radiation of monopole, and then the ripple of this direction outgoing can be thought plane wave.Produce the method for plane wave than tradition, the method is more flexible, has avoided a lot of loaded down with trivial details design cycles, is applicable to the different frequency ranges such as millimeter wave and THz wave.

For solving the problems of the technologies described above, the technical solution used in the present invention is as follows:

A kind of multi-beam antenna method for designing based on holographic impedance surface, described multi-beam antenna comprises square-shaped metal paster, medium substrate and ground plate, the square-shaped metal paster is amplexiformed in the one side middle of described medium substrate, and the another side of medium substrate amplexiforms ground plate; Described square-shaped metal paster is arranged by the impedance metal patch unit of band gap and is consisted of, and it is characterized in that, described multi-beam antenna method for designing comprises following steps:

Steps A, the chip unit resistance value Z of calculating band gap:

Z=jZ ₀k _z/k ₀

Wherein, j is imaginary unit, k ₀The free space wave number of chip unit, k _zThe vertical surface direction attenuation constant of chip unit, Z ₀It is the free space impedance of chip unit;

Step B, the gap g of calculating chip unit:

g=(-1.3360*10 ^-6Z ³+9.2688*10 ^-4Z ²-0.2189Z ¹+17.84)

Step C determines that monopole antenna is at holographic impedance meter ground roll ψ _rWith antenna exit plane ripple ψ _o, computing formula is respectively:

ψ _r=e ^-jknr

ψ _o=e ^jknxsin(-θ)+e ^jknxsin(+θ)

Wherein, θ is the exit plane wave line of propagation, and n is surperficial mean refractive index, and k is the free space wave number, r be monopole antenna in the position on holographic impedance surface,

X is the axial component of x axle, and y is the axial component of y axle;

Step D, by following formula antenna interference pattern equation, determine the paster impedance variation scope of band gap:

$Z(x,y)=j[X+\mathrm{MRe}\left({\mathrm{\ψ}}_r{\mathrm{\ψ}}_o^{*}\right)]$

Wherein, X is the average impedance value, and M is modulation rate, and real part computing, () are got in Re () expression ^*The computing of expression complex conjugate; By determining X and M value, make impedance Z (x, y) excursion consistent with band gap paster impedance variation scope.

The invention has the beneficial effects as follows: the present invention proposes a kind of multi-beam antenna method for designing based on holographic impedance surface, described method for designing is based on holographic impedance meter surface technology, described holographic impedance surface is by gapped metal patch cell formation each other, changes the resistance value of chip unit by adjusting gap between the metal patch unit; In conjunction with the principle of interference pattern in the microwave holography, determine the distribution of impedance of antenna surface; By the monopole antenna of an omnidirectional radiation, through the antenna pattern of outgoing designing requirement after the modulation of impedance interference pattern.Method for designing of the present invention is applicable to microwave, millimeter wave and THz wave wave band.

Description of drawings

Fig. 1 is antenna diagram of the present invention; Wherein, Fig. 1 (a) is impedance meter surface antenna structure figure; Fig. 1 (b) is the partial enlarged drawing of holographic impedance meter surface antenna of the present invention.

Fig. 2 is the emulation far-field radiation directional diagram of the embodiment of the invention; Wherein, Fig. 2 (a) is the E face directional diagram of 16.8GHz; Fig. 2 (b) is the E face directional diagram of 16.9GHz; Fig. 2 (c) is the E face directional diagram of 17GHz; Fig. 2 (d) is the E face directional diagram of 17.1GHz; Fig. 2 (e) is the E face directional diagram of 17.2GHz.

Fig. 3 is the S11 curve of the embodiment of the invention in the 16.8-17.2GHz frequency range.

Embodiment

Below in conjunction with accompanying drawing, a kind of multi-beam antenna based on holographic impedance surface that the present invention is proposed is elaborated: at first design the impedance of the chip unit of band gap.Calculate the dispersion curve of this structure with CSTMWS Electromagnetic Simulation software, obtain the variation relation of horizontal wave number kt and frequency.Getting frequency values is 17GHZ, and under this frequency values, the band gap paster structure is the perception surface, can support the TM ripple on its surface.Utilize (1) (2) formula

${\mathrm{<figure-callout\; id="2"\; label="k\; t"\; filenames="HDA00003496417700011.png"\; state="\{\{state\}\}">k</figure-callout>}}_t^{}={\mathrm{<figure-callout\; id="2"\; label="k\; z"\; filenames="HDA00003496417700011.png"\; state="\{\{state\}\}">k</figure-callout>}}_z^{}+{\mathrm{<figure-callout\; id="0"\; label="k"\; filenames="HDA00003496417700012.png,HDA00003496417700021.png"\; state="\{\{state\}\}">k</figure-callout>}}_0^2---\left(1\right)$

Z=jZ ₀k _z/k ₀ (2)

K wherein ₀The free space wave number, k _zVertical surface direction attenuation constant, Z ₀Be free space impedance, formula (1) can be derived formula (2) in conjunction with the Maxwell equation group, and the surface impedance value of Z this structure that to be us required.

By the impedance of the several different gap size of emulation chip unit, the data fitting method of using least square can obtain the change curve of gap length and resistance value.The expression formula of curve is as follows:

g=(-1.3360*10 ^-6Z ³+9.2688*10 ^-4Z ²-0.2189Z ¹+17.84) (3)

Secondly, according to the holographic interference pattern generating principle, can think that monopole antenna can produce surface wave on the impedance surface:

ψ _r=e ^-jknr (4)

Wherein n is surperficial mean refractive index, r be monopole antenna in the position on holographic impedance surface,

X is the axial component of x axle, and y is the axial component of y axle;

Designed exit plane ripple is:

ψ _o=e ^jknxsin(-θ)+e ^jknxsin(+θ) (5)

(5) in the formula ± θ is the plane wave line of propagation of outgoing, can make that θ is 60 °.

The interference pattern equation can be written as:

$Z(x,y)=j[X+\mathrm{MRe}\left({\mathrm{\&psi;}}_r{\mathrm{\&psi;}}_o^{*}\right)]---\left(6\right)$

Wherein X is the average impedance value, and M is modulation rate.By determining the size of X and M value, make the impedance variation scope of (6) formula consistent with band gap paster impedance variation scope.

At last, according to principle of holography, use reference wave, namely monopole antenna then generates the before dualbeam directed radiation of design on the surface wave excitation impedance surface of impedance meter surface radiation.

By reference to the accompanying drawings, the specific embodiments of the invention detailed annotation is as follows:

Antenna diagram of the present invention as shown in Figure 1; Wherein, Fig. 1 (a) is impedance meter surface antenna structure figure; Fig. 1 (b) is the partial enlarged drawing of holographic impedance meter surface antenna of the present invention.

Among Fig. 1, square-shaped metal paster 1 is amplexiformed in the one side middle of medium substrate 3, and the another side of medium substrate 3 amplexiforms ground plate 2; Described square-shaped metal paster 1 is arranged by the impedance metal patch unit of band gap and is consisted of; Integrated antenna is of a size of 606mm * 504mm.

A kind of multi-beam antenna based on holographic impedance surface, its physical dimension is: ground plate 2 is the thick metallic plate of 0.035mm, and the centre is 2.2 medium substrate 3 for dielectric constant, and thickness is 1.57mm, and metal patch 1 is that thickness is the metal patch array of 0.035mm; The center is SMA feed, and external diameter is 3.45mm, and internal diameter is 1mm.By utilizing monopole antenna to carry out feed at the center of antenna place, produce the radiation pattern of dualbeam outgoing in the far field.

The emulation far-field radiation directional diagram of the embodiment of the invention as shown in Figure 2; Wherein, Fig. 2 (a) is the E face directional diagram of 16.8GHz; Fig. 2 (b) is the E face directional diagram of 16.9GHz; Fig. 2 (c) is the E face directional diagram of 17GHz; Fig. 2 (d) is the E face directional diagram of 17.1GHz; Fig. 2 (e) is the E face directional diagram of 17.2GHz.

As can be seen from Figure 2, in this frequency range, the dualbeam directional diagram of institute's outgoing is apparent in view, gains very high, and main lobe is very narrow, and the first secondary lobe is lower, all is ± 60 ° of outgoing.

Fig. 3 is the S11 parameter value of this antenna, and its size has been reacted the stationary wave characteristic of this antenna current feed port.As can be seen from the figure, near center frequency point 17GHz, the port of antenna reflection is very little, and the S11 value is lower than-and the bandwidth of 10dB is 500MHz.

Holographic impedance surface two-beam antenna among the present invention is different according to working frequency range, can adopt different processing technologys to realize.

The above is method and the flow process of the holographic resistance technique design of utilization of the present invention multi-beam antenna; be noted that for those skilled in the art; under the prerequisite that does not break away from the principle of the invention; can also make some improvements and modifications, these improvements and modifications also should be considered as protection scope of the present invention.

Claims (1)

1. multi-beam antenna method for designing based on holographic impedance surface, described multi-beam antenna comprises square-shaped metal paster, medium substrate and ground plate, the square-shaped metal paster is amplexiformed in the one side middle of described medium substrate, and the another side of medium substrate amplexiforms ground plate; Described square-shaped metal paster is arranged by the impedance metal patch unit of band gap and is consisted of, and it is characterized in that, described multi-beam antenna method for designing comprises following steps:

Steps A, the chip unit resistance value Z of calculating band gap:

Z=jZ ₀k _z/k ₀

Wherein, j is imaginary unit, k ₀The free space wave number of chip unit, k _zThe vertical surface direction attenuation constant of chip unit, Z ₀It is the free space impedance of chip unit;

Step B, the gap g of calculating chip unit:

g=(-1.3360*10 ^-6Z ³+9.2688*10 ^-4Z ²-0.2189Z ¹+17.84)

Step C determines that monopole antenna is at holographic impedance meter ground roll ψ _rWith antenna exit plane ripple ψ _o, computing formula is respectively:

ψ _r=e ^-jknr

ψ _o=e ^jknxsin(-θ)+e ^jknxsin(+θ)

Wherein, θ is the exit plane wave line of propagation, and n is surperficial mean refractive index, and k is the free space wave number, r be monopole antenna in the position on holographic impedance surface, X is the axial component of x axle, and y is the axial component of y axle;

Step D, by following formula antenna interference pattern equation, determine the paster impedance variation scope of band gap:

$Z(x,y)=j[X+\mathrm{MRe}\left({\mathrm{\&psi;}}_r{\mathrm{\&psi;}}_o^{*}\right)]$

Wherein, X is the average impedance value, and M is modulation rate, and real part computing, () are got in Re () expression ^*The computing of expression complex conjugate; By determining X and M value, make impedance Z (x, y) excursion consistent with band gap paster impedance variation scope.

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