CN106602231A - Quasi-surface plasmon ultra-wide band low-scattering slot antenna - Google Patents

Abstract

The invention discloses a quasi-surface plasmon ultra-wide band low-scattering slot antenna. Radiation apertures have circular structures in same area; the radius of a circle is r1=68mm; the thickness of a dielectric slab of an SSPP slot antenna is 1mm; a metal coats a rear feeding part covering an area of 20mm*40mm on the SSPP slot antenna; a 26mm*2mm gap is formed on a central position of the SSPP slot antenna; the rest positions are not coated with the metal; a dielectric constant of the dielectric slab is 2.65; the loss tangent is less than 0.001. The quasi-surface plasmon ultra-wide band low-scattering slot antenna is realized by the invention; the antenna has an obvious RCS (Radar Cross Section) reduction effect within 1GHz-10GHz; the maximum reduction volume of MRCS is 16.93dB or above; the relative bandwidth of the SSPP slot antenna is 9.4%; the frequency coverage is 5.25GHz-5.77GHz; compared with the traditional antenna, the SSPP antenna has the advantage that the beam width is at least widened for 65 degrees.

Description

Quasi-surface plasmon ultra-wideband low-scattering slot antenna

Technical Field

The invention belongs to the field of novel electromagnetic metamaterials and application, and particularly relates to a quasi-surface plasmon ultra-wideband low-scattering slot antenna.

Background

Surface Plasmon Polaritons (SPP) are a Surface electromagnetic wave mode that usually exists on the Surface of two materials with opposite dielectric constants, and because of the Surface wave characteristics, electromagnetic waves (e.g., light waves) in certain frequency bands can be confined in a sub-wavelength spatial range. General surface plasmons exist mainly in nanostructures in the optical wavelength band. The ideal conductor equivalent dielectric constant of the subwavelength pore structure is that when electromagnetic waves enter the pores, the attenuation waveguide mode of the pores is excited, only the fundamental mode playing the dominant role of the super-transparency is considered, and the calculation result shows that: an ideal conductor with a subwavelength aperture has an approximately equivalent dielectric constant to the plasmonic material. From this result, when an electromagnetic wave is incident on an ideal conductor with a sub-wavelength aperture, a surface wave similar to SPP, called a quasi surface plasmon polariton (SSPP), is excited. SSPP research not only expands the research content of surface plasmons, but also expands the application field of the surface plasmons. In order to excite quasi-surface plasmons in the microwave band, researchers propose two types of methods: one is to excite SSPP by doping semiconductors, high temperature superconducting materials, etc.; the other is to reduce the surface plasma frequency of the metal by the metal surface microstructure. The former mainly uses the methods of photo-thermal excitation, ion injection and the like to control the carrier concentration, so that the plasma frequency is reduced, and the SSPP of a low frequency band is realized. The latter is due to the fact that the surface wave mode of SSPP can be supported by a periodically structured metal surface. The rapid development of Metamaterial injected new viability into the SSPP study in the microwave band. The SSPP wave propagation characteristics of the three-dimensional periodic groove-shaped structure are analyzed, and research results show that the designed groove structure can support the SSPP wave propagation of 0.8 THz. The structure of the shape of the Chinese character 'wang' is etched on the upper metal surface of the double-sided copper-clad plate, and the SSPP is excited by utilizing the structure. SSPP in a microwave frequency band is coupled out by combining a gradual change super surface (Metasurface) structure, and the SSPP surface wave propagation state on the structure is analyzed. The broadband SSPP characteristics of the periodic structure are analyzed, and researches show that the periodic CSRR ring can support the propagation of SSPP surface waves. The surface plasmon phenomenon of the circular quasi-super surface is analyzed, the fact that the super surface can excite SSPP under different polarizations is verified, and research results show that the quasi-super surface can effectively regulate and control the propagation direction of electromagnetic waves and improve the scattering characteristic of the quasi-super surface. These studies have advanced the development of SSPP, but since SSPP is very novel in the microwave band, there are few reports on its application in antennas.

The existing quasi-surface plasmon structure of the microwave frequency band is very sensitive to the polarization of incident waves due to the asymmetry problem of the designed structure; most of the structures can only excite TM-polarized SSPP according to the magnetic resonance characteristics of the structures, and the application of the structures in the antenna often brings about great improvement of cross polarization components and enhancement of co-polarization scattering, so that the radiation and scattering characteristics of the antenna are difficult to be considered.

Disclosure of Invention

The invention aims to provide a quasi-surface plasmon ultra-wideband low-scattering slot antenna, and aims to solve the problems that the existing quasi-surface plasmon structure in a microwave frequency band is very sensitive to polarization of incident waves due to the structure problem, most of the quasi-surface plasmon structure can only excite SSPP (transverse magnetic polarization), and the application of the quasi-surface plasmon structure in an antenna hardly considers radiation and scattering characteristics of the antenna.

The quasi-surface plasmon ultra-wideband low-scattering slot antenna is realized in such a way that the radiation calibers of the quasi-surface plasmon ultra-wideband low-scattering slot antenna are circular structures with the same area, and the radius of the circle is r₁The dielectric plate of the SSPP slot antenna is 68mm, the thickness of the dielectric plate is 1mm, the area of 20mm × 40mm at the back feeding position of the SSPP slot antenna is metal, the center position of the slot is 26mm × 2mm, metal is not plated at the rest positions, the dielectric constant of the dielectric plate is 2.65, and the loss tangent is less than 0.001.

Another objective of the present invention is to provide a design method of the quasi-surface plasmon ultra-wideband low scattering slot antenna, wherein the design method of the quasi-surface plasmon ultra-wideband low scattering slot antenna designs a circular quasi-super surface for exciting SSPP by using a gradual change double-sided sawtooth metal structure, and the quasi-super surface can excite SSPP on a metal structure with a low frequency band parallel to an electric field direction to form an SSPP mode surface wave and enhance energy propagation of the surface wave; the thickness of the quasi-super-surface structure is 1.0mm, and the relevant sizes of the metal bilateral sawtooth structure are respectively as follows: r is₁＝68mm,w₁＝32mm,w₂＝3.7mm,w₃2mm, 5mm, 25deg, 0.036mm metal thickness, 2.65 dielectric constant and no metal layer on the back of the dielectric plate.

Further, the design method of the ultra-wideband low-scattering slot antenna of the quasi-surface plasmon can excite the quasi-surface plasmon by using the metal bilateral sawtooth structure, so that the surface wave conversion from the radiated electromagnetic wave to the SSPP mode is realized, and the electric field E (x, y, z) of the incident electromagnetic wave is as follows:

wherein E is₀Kz and Kx represent components of wave numbers in the directions of z and x axes, and the direction of an electric field is along the direction of the x axis; electric field division incident on metalMeasurement ofComprises the following steps:

component of electric field on mediumComprises the following steps:

k_z1and₁representing wave number and dielectric constant, k, of the double-sided sawtooth structure metal layer_z2And₂represents the wave number and dielectric constant of the dielectric layer; when the electromagnetic wave is transmitted between the metal layer and the dielectric layer, the attenuation length of the electromagnetic wave is as follows:

according to the continuity boundary condition, the following dispersion relation is further obtained:

wherein k is_xRepresents an electromagnetic wave propagation coefficient along the x-axis direction; refractive index (n) of SSPP for metal and dielectric structures_SSPP) Comprises the following steps:

wherein,₁and₂respectively, the dielectric constants of different media. k is a radical of_xFurther simplifying as follows:

wherein k is₀W/c 2 pi f/c is the wave number in free space, and c is the speed of light.Write as:

surface wave propagation coefficient k of SSPP mode excited by bilateral sawtooth metal structure_xComprises the following steps:

when 0 is present<k₀d<At pi/2, k_xIs a real number, and k_x>k₀。

According to the ultra-wideband low-scattering slot antenna with the quasi-surface plasmons, the SSPP of a microwave frequency band is excited by designing the ultra-thin circular gradually-changed bilateral sawtooth symmetrical structure, the surface wave propagation and scattering characteristics under the SSPP mode condition are deeply analyzed, and the surface wave propagation and scattering characteristics are further used for the antenna radiation surface.

The invention combines a gradual change bilateral sawtooth structure with a circular symmetrical super surface and provides an ultrathin circular SSPP quasi-super surface. The SSPP of the quasi-super surface energy excited microwave frequency band deeply analyzes the surface wave propagation characteristic and the scattering characteristic under the SSPP mode condition, and then the surface wave propagation characteristic and the scattering characteristic are used for an antenna radiation surface, so that the ultra-wideband low-scattering slot antenna of the quasi-surface plasmon polariton is realized, the scattering wave beam of the antenna is regulated and controlled due to the influence of the SSPP, the antenna has an obvious RCS reduction effect in the position of 1 GHz-10 GHz, the maximum reduction of MRCS is more than 16.93dB, the relative bandwidth of the SSPP slot antenna is 9.4%, the frequency of the SSPP slot antenna covers 5.25 GHz-5.77 GHz, and compared with the traditional antenna, the wave beam width of the SSPP antenna is at least 65 degrees. Simulation and test verify that the SSPP slot antenna can regulate and control scattering beams, improve the scattering performance of the antenna and realize the characteristics of ultra wide band and low RCS, and meanwhile, the SSPP can widen the beam width of the antenna and optimize the radiation performance of the antenna.

Drawings

FIG. 1 is a schematic diagram of a polarization independent circular super-surface structure based on a tapered sawtooth structure provided by an embodiment of the present invention;

in the figure: (a) a progressive bilateral sawtooth structure; (b) a super-surface based on a double-sided sawtooth structure.

Fig. 2 is a schematic diagram of a simulation model of a dispersion curve according to an embodiment of the present invention.

Fig. 3 is a schematic diagram of a simulation result of a dispersion curve of a tapered sawtooth structure according to an embodiment of the present invention.

Fig. 4 is a schematic diagram of the distribution of the super-surface electric field under different polarized incident waves at normal incidence according to an embodiment of the present invention.

FIG. 5 is a schematic diagram of a super-surface waveguide slot antenna with a double-sided sawtooth structure according to an embodiment of the present invention;

in the figure: (a) waveguide slot antennas on conventional metal surfaces; (b) an SSPP slot antenna.

Fig. 6 is a diagram illustrating simulation results of S11 of different waveguide slot antennas according to an embodiment of the present invention.

FIG. 7 is a schematic diagram of simulation results of two-dimensional patterns of an SSPP antenna and a conventional metal-surfaced waveguide slot antenna at 5.4GHz and 5.65GHz, according to an embodiment of the present invention;

in the figure: (a) the yoz plane of the 5.4GHz radiation pattern; (b) xoz planes of the 5.4GHz radiation pattern; (c) the yoz plane of the 5.65GHz radiation pattern; (d) xoz planes of the 5.65GHz radiation pattern.

FIG. 8 is a schematic diagram of simulation results of three-dimensional pattern diagrams of an SSPP antenna provided by an embodiment of the present invention and a waveguide slot antenna with a conventional metal surface at 5.4GHz and 5.65 GHz;

in the figure: (a) conventional waveguide slot antennas; (b) an SSPP slot antenna; (c) conventional waveguide slot antennas; (d) an SSPP slot antenna.

FIG. 9 is a schematic diagram of 5.4GHz surface current distribution of an SSPP antenna provided by an embodiment of the invention and a waveguide slot antenna with a conventional metal surface;

in the figure: (a) a conventional antenna; (b) a super-surface antenna.

Fig. 10 is a comparison diagram of simulation results of a single station RCS of an SSPP antenna compared with a conventional antenna under different polarization conditions according to an embodiment of the present invention;

in the figure: (a) MRCS simulation comparison under the TM polarization condition; (b) and (5) MRCS simulation comparison under TE polarization condition.

Fig. 11 is a schematic diagram of a conventional waveguide slot antenna and an SSPP slot antenna processed according to an embodiment of the present invention.

Fig. 12 is a diagram illustrating the results of the S11 test for different antennas provided by an embodiment of the present invention.

FIG. 13 is a schematic diagram illustrating the results of the directional diagram test of the conventional waveguide slot antenna and SSPP slot antenna of 5.4GHz and 5.65GHz according to the embodiment of the present invention;

in the figure: (a) a 5.4GHz pattern; (b)5.65GHz pattern.

Fig. 14 is a schematic diagram of an actual measurement result of MRCS reduction of the antenna under different polarization conditions according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

According to the invention, the SSPP of a microwave frequency band is excited by designing an ultrathin round gradient bilateral sawtooth symmetrical structure, the surface wave propagation and scattering characteristics under the SSPP mode condition are deeply analyzed, and the surface wave propagation and scattering characteristics are further used for the antenna radiation surface, so that the antenna scattering wave beam direction is controlled, the wave beam width of the antenna is widened, the scattering and radiation performance of the antenna is improved, and the SSPP ultra-wideband low-scattering slot antenna is realized.

The following detailed description of the principles of the invention is provided in connection with the accompanying drawings.

(1) SSPP quasi-super surface

A circular quasi-super surface capable of exciting SSPP is designed by utilizing a gradual change bilateral sawtooth metal structure, as shown in figure 1. Fig. 1(a) shows a metal structure with gradually changed double-sided sawteeth, and fig. 1(b) shows that the metal structure is rotated around the center to form a circular quasi-super surface on the basis of the metal double-sided sawteeth structure. The designed quasi-super surface can excite SSPP on a metal structure with a low frequency band parallel to the direction of an electric field to form an SSPP mode surface wave and enhance the energy propagation of the surface wave; the thickness of the quasi-super-surface structure is 1.0mm, and the relevant sizes of the metal bilateral sawtooth structure are respectively as follows: r is₁＝68mm,w₁＝32mm,w₂＝3.7mm,w₃2mm, 5mm, 25deg, 0.036mm metal thickness, 2.65 dielectric constant, no metal on the back of the dielectric plateAnd (3) a layer.

In a microwave frequency band, quasi-surface plasmons can be excited by utilizing the metal double-sided sawtooth structure, and surface wave conversion from radiation electromagnetic waves to an SSPP mode is realized. Due to the strong central symmetry characteristic of the circular structure, the SSPP can be excited for incident waves with TE and TM polarization, and the propagation of SSPP surface waves is guided. For the quasi-super-surface structure of fig. 1, the electric field of the incident electromagnetic wave is:

wherein the electric field direction is along the x-axis direction. The components of the electric field incident on the metal are:

the electric field components on the medium are:

k_z1and₁representing wave number and dielectric constant, k, of the double-sided sawtooth structure metal layer_z2And₂the wave number and dielectric constant of the dielectric layer are shown. According to the formulas (2) and (3), when the electromagnetic wave passes between the metal layer and the dielectric layer, the attenuation length of the electromagnetic wave is as follows:

according to the continuity boundary condition, the following dispersion relation is further obtained:

wherein k is_xRepresenting the propagation coefficient of the electromagnetic wave along the x-axis direction. Refractive index (n) of SSPP for metal and dielectric structures_SSPP) Comprises the following steps:

combining equations (5) and (6), k_xIt can be further simplified as:

wherein k is₀W/c 2 pi f/c is the wave number in free space, and c is the speed of light.Can be written as:

as can be seen from the equation (9),showing the exponential decay relationship of the metal saw tooth structure and the medium. For the gradual change bilateral sawtooth structure, the reflection coefficient can be calculated according to the boundary condition by considering TM polarized incident waves. Surface wave conditions by SSPP mode have k_x>k₀. If the condition lambda is satisfied>>(P-w₃) And λ>>P, (λ is the operating wavelength), the surface wave propagation coefficient k of the SSPP mode excited by the double-sided sawtooth metal structure_xComprises the following steps:

from equation (10), when 0<k₀d<At pi/2, k_xIs a real number, and k_x>k₀Therefore, the propagation speed of the excited SSPP surface wave is lower than the speed of light. It can also be found from the formula (10) that k_xIncreases with increasing P and d. Meanwhile, the cut-off frequency of the surface wave of the SSPP mode is mainly determined by the depth d of the sawtooth, namely, the cut-off frequency of the designed quasi-super surface can be improved by increasing the depth of the metal sawtooth. Therefore, the propagation speed of the surface wave in the SSPP mode is lower than the speed of light, and meanwhile, the surface wave can be confined in the critical plane of metal and medium and propagates forwards along the sawtooth structure.

The dispersion curve of the gradual change sawtooth structure is simulated by utilizing the eigenmode of CST, the simulation model is shown as figure 2, and the dispersion curve obtained by simulation is shown as figure 3. As can be seen from the figure, different sawtooth depths d correspond to different cut-off frequencies, and when the sawtooth depths d are 4.47mm, 8.62mm and 12.61mm, the corresponding cut-off frequencies are 8.07GHz, 4.74GHz and 2.83GHz respectively; it can be seen that: as the depth d of the serrations increases, the cut-off frequency shifts to a lower frequency. When the depth d of the sawtooth is 4.47mm, the cut-off frequencies of the basic mode, the first-order mode and the second-order mode are 2.83GHz, 3.05GHz and 3.50GHz respectively; when the depth d of the sawtooth is 8.62mm, the cut-off frequencies of the first three modes are 4.74GHz, 5.49GHz and 6.31GHz respectively; when the depth d of the serrations is 12.61mm, the cut-off frequencies of the first three modes are 8.07GHz, 9.45GHz, and 10.86GHz, respectively. It can be seen that, under the same sawtooth depth condition, the cut-off frequency rises with the increase of the mode; as the modes increase, the cut-off frequency becomes closer to the propagation effect of the speed of light. Finally, the metal sawtooth structure with the d being 12.61mm is selected according to design requirements.

To verify the surface wave characteristics of the microwave SSPP mode, the super surface xoy plane electric field distributions at 1GHz and 2GHz were analyzed, as shown in fig. 4. As is clear from the electric field distribution simulation results in the figure, with respect to the incident electromagnetic wave of TM polarization, a significant surface wave of SSPP mode is formed at a position parallel to the y-axis direction, whereas a surface wave in the x-axis direction is not significant, and other positions have a significant surface wave propagation effect due to the coupling effect between the saw teeth. For incident electromagnetic waves with TE polarization, very obvious SSPP mode surface waves are formed at the position parallel to the direction of the x axis, while the surface waves in the direction of the y axis are not obvious, and the gradual change sawtooth structure at the rest positions also forms obvious surface wave propagation due to the coupling effect between sawteeth. The surface wave of the SSPP mode shows that the designed metal gradient sawtooth structure can excite quasi-surface plasmon of a microwave frequency band, and the designed super surface has polarization independence; the simulation results also demonstrate that a polarization-independent circular super-surface based graded-sawtooth structure is capable of converting a normally incident electromagnetic wave into a surface wave in SSPP mode.

(2) Quasi-surface plasmon ultra-wideband low-scattering slot antenna

The SSPP slot antenna structure is designed as shown in fig. 5. The radiation caliber of the antenna is a circular structure with the same area, and the radius of the circle is r₁The thickness of a dielectric plate of the SSPP slot antenna is 1mm, the thickness of a caliber metal plate of the traditional waveguide slot antenna is 1mm, the area of a back feeding position of the SSPP slot antenna is 20mm × 40mm, the area of the back feeding position of the SSPP slot antenna is metal, the center position of the slot antenna is 26mm × 2mm, the rest positions are not plated with metal, the dielectric constant of the dielectric plate is 2.65, the loss tangent is less than 0.001, red arrows mark feeding excitation of the slot antenna, and HFSS is used for simulation analysis of radiation and scattering performance of the antenna.

The simulation result of S parameter of the antenna is shown in FIG. 6, and the conventional antenna satisfies S₁₁<The-10 dB bandwidth is 5.34-5.86 GHz, and the SSPP slot antenna meets the requirement of S₁₁<The bandwidth of-10 dB is 5.28-5.72 GHz, and the working bandwidth of the antenna is shifted to low frequency. Fig. 7 and 8 show two-dimensional and three-dimensional patterns of the metal antenna at 5.4GHz and 5.65 GHz. As can be seen from the two-dimensional directional diagram curves of 5.4GHz and 5.65GHz in fig. 7, the cross polarization components of the SSPP slot antenna at 5.4GHz and 5.65GHz are slightly increased compared with the cross polarization component of the conventional waveguide slot antenna, and the backward direction isThe radiation is enhanced and the front-to-back ratio of the antenna is reduced. The conventional antenna and the SSPP slot antenna have beam widths of 146 ° and 200 ° at xoz plane of 5.4GHz, 70 ° and 72 ° at yoz plane, 151 ° and 172 ° at xoz plane of 5.65GHz, and 58 ° and 105 ° at yoz plane, respectively. As can be seen from the antenna three-dimensional directional pattern 8, the beam of the SSPP antenna is significantly widened compared with the waveguide slot antenna beam on the metal surface. Fig. 9 shows the surface current distribution of the SSPP antenna and the conventional metal surface waveguide slot antenna, and the current distribution density can find that: compared with the current density of the metal caliber, the current density along the horizontal direction is obviously enhanced, namely, the surface wave strength is improved through the sawtooth structure, and the broadening of the beam width is realized.

The MRCS results for the conventional waveguide slot antenna and the SSPP quasi-super-surface slot antenna are shown in fig. 10. The comparison of the results of the MRCS simulation shows that: compared with the traditional waveguide slot antenna, the SSPP slot antenna can obtain obvious RCS reduction in the range of 1 GHz-10 GHz, and the maximum RCS reduction exceeds 15 dB.

(3) Experimental test and analysis of SSPP slot antenna

The conventional waveguide slot antenna and the SSPP slot antenna were manufactured as shown in fig. 11, and the two types of antennas were placed in a microwave dark room for testing. The vector network analyzer used is Agilent N5230C, and the tested horn antenna can work in the frequency band range of 1 GHz-18 GHz. FIG. 12 shows S of the antenna₁₁Test results, fig. 13 shows the pattern test results of the antennas 5.4GHz and 5.65 GHz. From S₁₁The test result shows that the traditional waveguide slot antenna can obtain 9.1% relative bandwidth of 5.32 GHz-5.83 GHz; the SSPP slot antenna realizes 9.4% of relative bandwidth, and the frequency of the SSPP slot antenna covers 5.25 GHz-5.77 GHz.

The pattern test results of the two antennas at 5.4GHz and 5.65GHz are shown in FIG. 13. The 3dB beam widths of the E surface and the H surface of the traditional waveguide slot antenna pattern at 5.4GHz are respectively 132 degrees and 66 degrees, and the beam widths of the antenna pattern at 5.65GHz are respectively 143 degrees and 56 degrees; the measured beam widths of the SSPP slot antenna at 5.4GHz and 5.65GHz are 185 degrees, 70 degrees, 167 degrees and 102 degrees respectively, and compared with the traditional antenna, the beam width of the SSPP slot antenna is widened by at least 65 degrees. The SSPP slot antenna beam is obviously widened, and the simulation result and the actual measurement result are compared, so that the matching is better.

The MRCS test results for both antennas are shown in fig. 14. As can be seen from the figure, the SSPP antenna has a more obvious MRCS reduction effect than the traditional waveguide slot antenna in the range of 1GHz to 10GHz, but the reduction effect at the position of 2.8GHz to 4GHz is slightly worse. The maximum reduction of MRCS of the x-polarized antenna at 2.04GHz is 16.93dB, and the maximum reduction of MRCS of the y-polarized antenna at 1.78GHz is 23.83 dB. The RCS reduction at 2GHz is mainly caused by the change of the direction of the scattered beam of the electromagnetic wave by the super surface based on the quasi-surface plasmon of the microwave band. The reason why the MRCS reduction effects under different polarizations are not completely consistent includes two aspects, that is, the antenna slot structure is a narrow and long slot, and that the antenna itself has polarization characteristics. Comparing fig. 10 and 14, it can be seen that the measured values and the simulated values are consistent well.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims (3)

1. The ultra-wideband low-scattering slot antenna of the quasi-surface plasmon is characterized in that the radiation caliber of the ultra-wideband low-scattering slot antenna of the quasi-surface plasmon is a circular structure with the same area, and the radius of a circle is r₁The dielectric plate of the SSPP slot antenna is 68mm, the thickness of the dielectric plate of the SSPP slot antenna is 1mm, the area of the power feeding position of the back surface of the SSPP slot antenna, which is 20mm × 40mm, is metal, the center position of the slot is 26mm × 2mm, the rest positions are not plated with metal, the dielectric constant of the dielectric plate is 2.65, and the loss tangent is less than 0.001.

2. The design method of the quasi-surface plasmon ultra-wideband low-scattering slot antenna as claimed in claim 1, wherein the design method of the quasi-surface plasmon ultra-wideband low-scattering slot antenna utilizes a graded double-edge sawtooth metal structure to design a circular quasi-super surface for exciting SSPP, and the quasi-super surface can excite SSPP on the metal structure with a low frequency band parallel to the electric field direction to form an SSPP mode surface wave and enhance energy propagation of the surface wave; the thickness of the quasi-super-surface structure is 1.0mm, and the relevant sizes of the metal bilateral sawtooth structure are respectively as follows: r is₁＝68mm,w₁＝32mm,w₂＝3.7mm,w₃2mm, 5mm, 25deg, 0.036mm metal thickness, 2.65 dielectric constant and no metal layer on the back of the dielectric plate.

3. The method for designing the quasi-surface plasmon ultra-wideband low-scattering slot antenna as claimed in claim 2, wherein the quasi-surface plasmon ultra-wideband low-scattering slot antenna is designed by using a metal double-sided sawtooth structure to excite quasi-surface plasmons, so as to realize surface wave conversion from radiated electromagnetic waves to SSPP modes, and the electric field of the incident electromagnetic waves is:

$E(x,y,z)=E_0{e}^{i(k_{x}x-k_z|z|-\mathrm{\&omega;}t)};$

wherein the direction of the electric field is along the direction of the x axis; the components of the electric field incident on the metal are:

$E_{(x,y,z)}^{metallic}=\left[\begin{array}{c}{E}_x^m\\ E_y^m\\ E_z^m\end{array}\right]=\left[\begin{array}{c}{E}_0{e}^{i(k_{x}x-k_{z1}|z|-\mathrm{\&omega;}t)}\\ 0\\ E_0(-k_x/k_{z1})e^{i(k_{x}x-k_{z1}|z|-\mathrm{\&omega;}t)}\end{array}\right];$

the electric field components on the medium are:

$E_{(x,y,z)}^{dielectric}=\left[\begin{array}{c}{E}_x^d\\ E_y^d\\ E_z^d\end{array}\right]=\left[\begin{array}{c}{E}_0{e}^{i(k_{x}x-k_{z2}|z|-\mathrm{\&omega;}t)}\\ 0\\ E_0(-{\mathrm{\&epsiv;}}_1{k}_x/{\mathrm{\&epsiv;}}_2{k}_{z1})e^{i(k_{x}x-k_{z2}|z|-\mathrm{\&omega;}t)}\end{array}\right];$

k_z1and₁representing wave number and dielectric constant, k, of the double-sided sawtooth structure metal layer_z2And₂represents the wave number and dielectric constant of the dielectric layer; when the electromagnetic wave is transmitted between the metal layer and the dielectric layer, the attenuation length of the electromagnetic wave is as follows:

$\hat{z}=\frac{1}{\left|k_z\right|};$

according to the continuity boundary condition, the following dispersion relation is further obtained:

$k_x=\frac{\mathrm{\&omega;}}{c}{n}_{SSPP};$

$k_{z1,2}^2={\mathrm{\&epsiv;}}_{1,2}{(\mathrm{\&omega;}/c)}^2-k_x^2;$

wherein k is_xRepresents an electromagnetic wave propagation coefficient along the x-axis direction; refractive index n of SSPP for metal and dielectric structures_SSPPComprises the following steps:

$n_{sspp}=\sqrt{{\mathrm{\&epsiv;}}_1{\mathrm{\&epsiv;}}_2/({\mathrm{\&epsiv;}}_1+{\mathrm{\&epsiv;}}_2)};$

k_xfurther simplifying as follows:

$k_x=\frac{\mathrm{\&omega;}}{c}\sqrt{{\mathrm{\&epsiv;}}_1{\mathrm{\&epsiv;}}_2/({\mathrm{\&epsiv;}}_1+{\mathrm{\&epsiv;}}_2)}=k_0\sqrt{{\mathrm{\&epsiv;}}_1{\mathrm{\&epsiv;}}_2/({\mathrm{\&epsiv;}}_1+{\mathrm{\&epsiv;}}_2)};$

wherein k is₀W/c 2 pi f/c is the wave number in free space, c is the speed of light,write as:

$k_{z1,2}^2={\mathrm{\&epsiv;}}_{1,2}{k}_0^2\&lsqb;1-{\left(\frac{{\mathrm{\&epsiv;}}_1{\mathrm{\&epsiv;}}_2}{{\mathrm{\&epsiv;}}_1+{\mathrm{\&epsiv;}}_2}\right)}^2\&rsqb;;$

surface wave propagation coefficient k of SSPP mode excited by bilateral sawtooth metal structure_xComprises the following steps:

$k_x=k_0\sqrt{1+\frac{{(P-w_3)}^2}{P^2}{\tan }^2\left(k_{0}d\right)};$

when 0 is present<k₀d<At pi/2, k_xIs a real number, and k_x>k₀。