CN103078185B - High-gain low-radar cross section panel antenna based on artificial electromagnetic structural material - Google Patents

Abstract

The invention provides a high-gain and low-radar-scattering cross-section planar antenna based on an artificial electromagnetic structure material. The antenna is composed of a microstrip patch and a periodic artificial structure material with different reflection characteristics on both sides. The artificial structure material is composed of a dielectric substrate, a periodic metal square ring structure fabricated on the front side of the substrate, and a periodic metal planar structure with open gaps fabricated on the reverse side. The center of the four sides of the metal square ring structure on the front is loaded with concentrated resistance elements. When the electromagnetic wave is incident from the front of the artificial structure material, the energy of the electromagnetic wave is mainly absorbed; when the electromagnetic wave is incident from the back of the artificial structure material, the energy of the electromagnetic wave is mainly reflected. The artificial structure material is placed on the top of the microstrip patch as a coating, and its reverse side is used as a part of the reflective surface and the metal ground plate of the microstrip patch to form a FP resonant cavity, which improves the radiation gain of the antenna; its front can absorb external incident waves and reduce The radar cross section of the antenna.

Description

High gain and low radar cross section panel antenna based on artificial electromagnetic structure material

technical field

The invention relates to a high-gain, low-RCS panel antenna, in particular to a high-gain, low-RCS panel antenna based on artificial electromagnetic structure materials.

Background technique

As the radar cross section of the aircraft continues to decrease, the contribution of the airborne antenna system to the radar cross section of the flight system becomes increasingly prominent. Therefore, reducing the RCS of the antenna system has become an important factor in the target stealth system. Flat panel antennas (such as microstrip and F-P cavity antennas) have the advantages of light weight, low cost, and easy conformation, and are widely used in flight devices. Therefore, reducing the RCS of the panel antenna and increasing the gain of the panel antenna have attracted more and more attention and research of researchers. However, traditional radar absorbing materials and radar absorbing structures reduce the gain and directivity of the antenna while reducing the RCS. In recent years, many RCS technologies based on artificial electromagnetic structural materials to reduce antennas have been reported. Hong-Kyu Jang and other researchers used the new electromagnetic bandgap structure as the radar absorbing material to realize the reduction of the antenna RCS (H.-K.Jang, et al.Design and fabrication of a microstrip patch antenna with a low radar crosssection in the X-band[J], Smart Mater.Struct.015007(2011)), after loading the electromagnetic bandgap structure material, the RCS of the microstrip patch has been well reduced in the frequency band from 8.5GHz to 12GHz, and it is around 11GHz , the RCS of the antenna is reduced by nearly 20 decibels. Because the material exhibits good reflection performance near 3.2GHz, it has little influence on the directivity and gain of the antenna, but the RCS in-band reduction is not realized. Simone Genovesi and other researchers realized the reduction of large-angle RCS based on the frequency selective surface of artificial structural materials (S.Genovesi, et al. Low-Profile Array With Reduced Radar Cross Section by Using Hybrid Frequency Selective Surfaces[J], IEEETRANSACTIONS ON ANTENNAS AND PROPAGATION, VOL.60, NO.5, MAY2012), but after using artificial structural materials, the directivity of the antenna is reduced by about two decibels compared with the original antenna. In this patent, the artificial electromagnetic structure material is used to load on the microstrip patch; the radiation gain of the antenna can be improved, and the RCS of the antenna can be reduced at the same time.

To sum up, in the existing design schemes for reducing the RCS of the antenna, the radiation performance of the antenna will be affected while the RCS is reduced; and it is difficult to realize the RCS reduction of the in-band and out-of-band broadband.

Contents of the invention

The technical problem to be solved by the present invention is: to overcome the difficulty in realizing in-band reduction, narrow bandwidth reduction and the influence on the original antenna gain in the existing antenna RCS reduction technology; RCS panel antenna, this design scheme can not only improve the gain of the original antenna, but also greatly reduce the RCS in-band and out-of-band of the original antenna.

The technical solution adopted by the present invention to solve the technical problem is: a high-gain low radar cross-section planar antenna based on artificial electromagnetic structural materials, including periodic artificial structural materials with different reflection characteristics on the front and back sides, and microstrip patches , a metal ground plate and a dielectric plate with a microstrip patch; the periodic artificial structure material with different reflection characteristics on the front and back sides is composed of a dielectric substrate, an absorbing surface above the dielectric substrate, and a part of the reflective surface below the dielectric plate; the absorbing surface It is composed of a periodic metal square ring structure and a concentrated resistance element loaded in the center of the four sides of the square ring; part of the reflective surface is composed of a periodic open gap metal planar structure; on the one hand, when external electromagnetic waves irradiate on the absorbing surface, the The material can convert the external electromagnetic wave into heat loss, thereby reducing the RCS of the antenna; on the other hand, the electric field polarization direction of the microstrip patch radiation wave is parallel to the x-axis, and the partial reflective surface and the metal ground plate of the microstrip patch form a The F-P resonant cavity can greatly increase the gain of the antenna.

Wherein, the dielectric constant of the dielectric substrate is ε _r1 , the value range of the thickness h ₁ of the dielectric substrate is λ _m1 /20～λ _m1 /5, and the value range of the period p of the metal square ring structure is λ _m1 / 5～3*λ _m1 /5, the value range of the broadband w ₁ of the metal square ring structure is λ _m1 /30～λ _m1 /10, the value range of the side length b of the metal square ring structure is λ _m1 /6～ λ _m1 /2, the value range of the central opening width g of the four sides of the metal square ring structure is λ _m1 /60～λ _m1 /10; where λ _m1 is the corresponding value at the center frequency of the absorption frequency band of the wave-absorbing surface of the material effective wavelength, λ ₀₁ is the wavelength in vacuum corresponding to the center frequency.

Among them, the gap broadband of the open gap metal planar structure is w ₂ , and the value range of w ₂ is λ _m2 /300~λ _m2 /50; the length l of the open gap metal planar structure ranges from λ _m2 /6~3* λ _m2 /5; the value range of the distance d between the gaps in the open gap metal planar structure is λ _m2 /15~2*λ _m2 /5; the value range of the length and width of the microstrip patch is λ _m2 /4 ~λ _m2 ; the dielectric constant of the dielectric plate of the microstrip patch is ε _r2 , the thickness h ₂ of the dielectric plate of the microstrip patch is in the range of λ _m2 /30~λ _m2 /5; the thickness of the metal grounding h3 The range of values is λ _m2 /30~λ _m2 /4; where λ _m2 is the equivalent wavelength corresponding to the operating frequency of the antenna, λ ₀₂ is the wavelength in vacuum corresponding to the operating frequency.

The beneficial effects that the present invention has are:

(1) The structure of the present invention is simple, and the periodic artificial structural material 1 with different reflection characteristics on the front and back sides is a planar structure, which is easy to manufacture and can be manufactured by using PCB board processing technology, and this processing technology is now very mature.

(2) In the present invention, when an external electromagnetic wave is irradiated on the absorbing surface 5, the material can bind the external electromagnetic wave and convert it into heat loss, thereby reducing the RCS of the antenna both in-band and out-of-band. On the other hand, because the partial reflection surface 7 has high reflection and certain transmission, the partial reflection surface 7 and the metal ground 3 can form an F-P resonant cavity, which can greatly improve the gain of the antenna.

Description of drawings

Fig. 1 is a unit structure diagram of a high-gain, low RCS planar antenna based on artificial electromagnetic structural materials and a periodic artificial structural material 1 with different reflection characteristics on both sides of the present invention;

Fig. 2 obtains the transmittance and the reflectivity of the wave-absorbing surface 5 and the reflective surface 7 for the unit structure simulation of the artificial electromagnetic structure material of the present invention;

Fig. 3 is the return loss of the high-gain, low RCS planar antenna based on the artificial electromagnetic structure material of the present invention;

Fig. 4 is the far-field pattern of the E plane of the antenna at 11.5 GHz when the high-gain, low RCS panel antenna based on the artificial electromagnetic structure material and the periodic artificial structure material 1 with different reflection characteristics on the front and back sides are not covered in the present invention.

Fig. 5 is the far-field pattern of the H surface of the antenna at 11.5 GHz when the high-gain, low-RCS panel antenna based on the artificial electromagnetic structure material and the periodic artificial structure material 1 with different reflection characteristics on the front and back sides of the present invention are not covered.

Fig. 6 is a graph showing the relationship between RCS and frequency of the high-gain, low-RCS panel antenna based on the artificial electromagnetic structural material of the present invention and the periodical artificial structural material 1 with different reflection characteristics on the front and back without covering.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited to the following examples, but should include all content in the claims. Moreover, those skilled in the art can realize all the content in the claims from the following embodiment.

Figure 1 is a high-gain, low-RCS panel antenna based on artificial electromagnetic structural materials and a unit structural material diagram of artificial structural materials. In the figure, 1 represents a periodic artificial structural material with different reflection characteristics on both sides, and 2 represents a microstrip patch. 3 represents the metal ground plane, 4 represents the dielectric plate of the microstrip patch, 5 represents the reflective surface, 6 represents the dielectric substrate, 7 represents the absorption surface, 8 represents the metal square ring structure, 9 represents the concentrated resistance element, and 10 represents the open gap metal planar structure , 11 represents the external incident wave, and 12 represents the outgoing wave. The specific implementation process is as follows:

(1) Using the traditional photolithography process, spin-coat photoresist on the metal layer of a double-sided copper-clad microwave PCB board (model Rogers4003) with a dielectric constant of 3.38, a length and width of 60mm×60mm, and a thickness of 3.25mm. Drying and curing, exposure, development, drying and hardening, wet etching of the metal layer and other steps, a metal square ring structure with a cycle number of 5×5 four sides with openings is produced on the front side of the microwave PCB board, and at the same time, it is produced on the back side A metal planar structure with open gaps of period 5×5 is produced, and then a concentrated resistance element is welded in the four openings of the metal square ring structure; the shape of each unit is the metal square ring structure in Figure 1, the loaded concentrated resistance and the open gap The shape shown in the metal planar structure. The above-mentioned microwave PCB board (model Rogers4003) is a dielectric substrate 6 of artificial structural materials with different reflectivity on the front and back sides. The parameter size taken in this example is: the period p of the metal square ring structure 8 and the open gap metal plane structure 10 is 12mm, the side length b of the metal square ring structure 8 is 7mm, and the width _w1 of the metal square ring structure 8 is 0.5mm , the central opening width g of the four sides of the metal square ring structure 8 is 1mm, and the resistance value of the concentrated resistor 9 loaded on the four sides of the metal square ring structure 8 is 110Ω. The gap width w ₂ in the open gap metal planar structure 10 is 0.15 mm, the gap length l is 8 mm, and the period d of the gap along the x-axis direction is 4 mm.

(2) Using the traditional photolithography process, spin-coat photolithography on the front metal layer of a single-sided copper-clad microwave PCB board (model Arlon AD250) with a dielectric constant of 2.5, a length and width of 60mm×60mm, and a thickness of 1.524mm. Gluing, drying and curing, exposure, development, drying and hardening, wet etching of the metal layer and other steps, a metal square structure is produced on the front center of the microwave PCB board as a microstrip patch 3. The microwave PCB board (model ArlonAD250) is used as the dielectric board 4 of the microstrip patch, and the parameter size of the microstrip patch 3 is: 13.8mm×13.8mm.

(3) A metal aluminum plate with a length and width of 60mm×60mm and a thickness of 6mm is used as the metal ground plate 3 of the antenna, which is closely attached to the dielectric plate 4 of the microstrip patch. The distance between the metal ground plate 3 and the artificial structural material 1 with different reflectivity on the front and back sides is 13 mm.

The artificial structural materials with different reflectivity in the high-gain, low RCS panel antenna based on artificial electromagnetic structural materials of the present invention are simulated by the finite difference time domain method (FDTD) as shown in Figure 1, and the vertical coordinates in the figure The unit is decibel, and the abscissa is frequency. The solid line in the figure indicates the transmittance of the linearly polarized wave whose electric field direction is parallel to the x-axis. It can be seen that there is a certain transmittance near 11.5GHz, while that of The transmittance is less than -10 decibels. The partially reflective surface has high reflectivity at 6-12GHz, especially the reflectivity near the operating frequency of 11.5GHz is greater than -2.5 decibels, and can be used to construct a high-gain F-P resonant cavity. The reflectivity of the absorbing surface at 6.5-11GHz is less than -10 decibels, which shows that it has good absorption performance for electromagnetic waves in this frequency band.

The high-gain, low-RCS planar antenna based on the artificial electromagnetic structure material of the present invention is shown in Figure 2 by the FDTD simulation result, and the ordinate in this figure is the return loss, and the abscissa is the frequency, and the antenna echo near 11.5GHz If the loss is less than -10dB, the antenna can work normally.

The high-gain, low RCS planar antenna based on artificial electromagnetic structural materials of the present invention and the antenna of periodic artificial structural materials that do not cover the different reflection characteristics of the front and back sides are as shown in Figure 3 through FDTD simulation results, and the vertical coordinates in the figure is the antenna gain, and the abscissa is the angle. The solid line in the figure represents the far-field pattern of the E-plane of the high-gain, low-RCS panel antenna based on artificial electromagnetic structure materials; the dotted line represents the periodicity that does not cover the different reflection characteristics of the front and back sides Antenna E-plane far-field pattern of artificial structural materials. It can be seen that the antenna gain is increased from 7dB to 14dB after covering the material, and the beam width is reduced at the same time. The solid line in Figure 4 shows the far-field pattern of the H-plane of the high-gain, low-RCS panel antenna based on artificial electromagnetic structure materials; field pattern.

The high-gain, low RCS planar antenna based on the artificial electromagnetic structural material of the present invention and the antenna of the periodic artificial structural material that do not cover the different reflection characteristics of the front and back sides are as shown in Figure 6 through the FDTD simulation results, and the ordinate in the figure is the RCS of the antenna, and the abscissa is the angle. The solid line in the figure represents the RCS of a high-gain, low-RCS panel antenna based on artificial electromagnetic structural materials; Antenna RCS. It can be seen that the RCS of the antenna has been significantly reduced at 6-14GHz after covering the material.

Parts not described in detail in the present invention belong to the known techniques of those skilled in the art.

Claims (3)

1. the high-gain low radar scattering cross section plate aerial based on manual electromagnetic structure material, it is characterized in that: comprise that tow sides have periodicity artificial structure's material (1) of different reflection characteristics, and the dielectric-slab (4) of microband paste (2), metal ground plate (3) and microband paste; Tow sides have periodicity artificial structure's material (1) of different reflection characteristics by medium substrate (6), and the part reflecting surface (7) of the sorbent surface (5) of medium substrate (6) top and medium substrate (6) below forms; Wherein sorbent surface (5) is by periodic metal side ring structure (8), and the side's of being carried in ring four paracentral lumped resistance elements (9) form; Part reflecting surface (7) is made up of periodic aperture slots metal flat structure (10); On the one hand, when external electromagnetic wave irradiation is when sorbent surface (5), this material can convert external electromagnetic wave to thermal losses, thereby has reduced the RCS (RCS) of antenna; On the other hand, the parallel x axle of E field polarization direction of microband paste (2) radiated wave, x direction of principal axis is parallel to metal ground plate (3), the metal ground plate (3) of part reflecting surface (7) and microband paste forms a F-P resonant cavity, can increase substantially the gain of antenna.

2. the high-gain low radar scattering cross section plate aerial based on manual electromagnetic structure material according to claim 1, is characterized in that: the dielectric constant of described medium substrate (6) is ε _r1, the span of the thickness h 1 of medium substrate (6) is λ _m1/ 20～λ _m1/ 5, the span of the period p of metal side's ring structure (8) is λ _m1/ 5～3* λ _m1/ 5, the span of the width w1 of metal side's ring structure (8) is λ _m1/ 30～λ _m1/ 10, the span of the side length b of metal side's ring structure (8) is λ _m1/ 6～λ _m1/ 2, the span of four limit central opening width g of metal side's ring structure (8) is λ _m1/ 60～λ _m1/ 10; Wherein λ _m1for the effective wavelength corresponding to absorption frequency range centre frequency place of the sorbent surface (5) of described material, λ ₀₁centered by wavelength in vacuum corresponding to frequency place.

3. the high-gain low radar scattering cross section plate aerial based on manual electromagnetic structure material according to claim 1, is characterized in that: the gap width of aperture slots metal flat structure (10) is w ₂, w ₂span be λ _m2/ 300～λ _m2/ 50; The length l span of aperture slots metal flat structure (10) is λ _m2/ 6～3* λ _m2/ 5; The span of spacing d between aperture slots metal flat structure (10) gap is λ _m2/ 15～2* λ _m2/ 5; The length of microband paste (2) and wide span are λ _m2/ 4～λ _m2; The dielectric constant of the dielectric-slab (4) of microband paste is ε _r2, the span of the thickness h 2 of the dielectric-slab (4) of microband paste is λ _m2/ 30～λ _m2/ 5; The thickness h of metal ground plate (3) ₃span be λ _m2/ 30～λ _m2/ 4; Wherein λ _m2for the corresponding effective wavelength in operating frequency place of described antenna, λ ₀₂for the wavelength in vacuum corresponding to operating frequency place.