Circularly polarized antenna based on multi-modal frequency selective surface, integrated method and terminal

Abstract

The application relates to the technical field of wireless communication and antenna design, and discloses a circularly polarized antenna based on a multi-modal frequency selection surface, an integration method and a terminal. On the circularly polarized antenna body, a wave-absorbing layer, a first diffuse reflection layer and a second diffuse reflection layer are integrated in sequence from top to bottom; wherein the circularly polarized antenna body has a working frequency band, the wave-absorbing layer has a wave-absorbing frequency band, the first diffuse reflection layer has a first diffuse reflection frequency band, and the second diffuse reflection layer has a second diffuse reflection frequency band; the four frequency bands of the working frequency band, the wave-absorbing frequency band, the first diffuse reflection frequency band and the second diffuse reflection frequency band are efficiently integrated, the high-flexibility radiation and the strong electromagnetic stealth requirement are met, and the multi-modal radiation stealth integrated array antenna design is realized. The application can efficiently suppress the radar cross section (RCS) out of the band while not affecting the in-band radiation efficiency of the antenna, and fundamentally realizes the fusion target of the high-performance radiation and the ultra-wideband RCS suppression stealth.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wireless communication and antenna design, and particularly relates to a circularly polarized antenna based on a multi-modal frequency selective surface, an integration method and a terminal. BACKGROUND

[0002] The development of modern electromagnetic environment puts forward more severe electromagnetic stealth protection requirements for high-speed penetration equipment, and how to improve the battlefield survivability of penetration equipment is a problem to be solved. Among these equipments, the antenna often brings strong radar echo scattering due to its necessary outward radiation function, thereby increasing the probability of being detected.

[0003] Multi-modal stealth electromagnetic surfaces can flexibly manipulate the amplitude, phase and polarization characteristics of incident electromagnetic waves, and are widely used in the suppression of radar cross section (RCS). The electromagnetic surface can flexibly manipulate the amplitude and phase characteristics of the incident electromagnetic wave according to the frequency, thereby realizing the functions of bandpass / bandstop electromagnetic surfaces with transmission / reflection performance, wave-absorbing electromagnetic surfaces with amplitude suppression function, and polarization conversion electromagnetic surfaces with phase manipulation function. However, these electromagnetic surfaces can only realize a single function, and it is difficult to cope with the modern complex electromagnetic environment. While reducing the RCS of the antenna by using the stealth electromagnetic surface, it is necessary to ensure that the radiation performance of the antenna is not affected, which is a difficulty in designing the stealth electromagnetic surface.

[0004] In view of this, it is urgent to provide an antenna which can suppress the out-of-band RCS without affecting the in-band radiation efficiency of the antenna, and has good stealth effect. SUMMARY

[0005] The purpose of the present application is to provide a circularly polarized antenna based on a multi-modal frequency selective surface, an integration method and a terminal, which embeds absorption, transmission and scattering modes into the multi-modal frequency selective surface, can realize independent manipulation of each mode, can suppress the out-of-band RCS without affecting the in-band radiation efficiency of the antenna, and has good stealth effect.

[0006] To achieve the above purpose, the present application adopts the following technical solutions:

[0007] In a first aspect, the present application provides a circularly polarized antenna based on a multi-modal frequency selective surface, which has an absorption layer, a first diffuse reflection layer and a second diffuse reflection layer integrated in sequence from top to bottom on the body of the circularly polarized antenna; wherein the body of the circularly polarized antenna has a working frequency band, the absorption layer has an absorption frequency band, the first diffuse reflection layer has a first diffuse reflection frequency band, and the second diffuse reflection layer has a second diffuse reflection frequency band; the working frequency band, the absorption frequency band, the first diffuse reflection frequency band and the second diffuse reflection frequency band neither intersect nor overlap.

[0008] As a possible implementation manner, the wave-absorbing layer comprises a dielectric substrate, the dielectric substrate comprises opposite first and second surfaces, the first surface is formed with first metal strips, and the second surface is formed with second metal strips, the first metal strips and the second metal strips are perpendicular but do not intersect, and a chip resistor is arranged at a perpendicular point of each of the first metal strips and the second metal strips.

[0009] As a possible implementation manner, the dielectric substrate is a rectangular dielectric substrate, the first metal strips are first curved metal strips formed on a first diagonal line of the rectangular dielectric substrate, and the second metal strips are second curved metal strips formed on a second diagonal line of the rectangular dielectric substrate.

[0010] As a possible implementation manner, the first diffuse reflection layer has opposite first and second surfaces, the first surface is opposite to the wave-absorbing layer, the first surface is divided into a plurality of first diffuse reflection regions, a first diffuse reflection metal strip arranged in a regular matrix is arranged in each of the first diffuse reflection regions, the first diffuse reflection metal strips in the same first diffuse reflection region have a consistent tilting direction, and the first diffuse reflection metal strips in adjacent first diffuse reflection regions are symmetrically arranged with adjacent edges as the axis of symmetry.

[0011] The second diffuse reflection layer has opposite first and second surfaces, the first surface is opposite to the first diffuse reflection layer, the first surface is divided into a plurality of second diffuse reflection regions, the number and area of the second diffuse reflection regions are equal to those of the first diffuse reflection regions, and one first diffuse reflection region corresponds to one second diffuse reflection region in space, a second diffuse reflection metal strip arranged in a regular matrix is arranged in each of the second diffuse reflection regions, and the tilting direction of the second diffuse reflection metal strip is perpendicular to the tilting direction of the first diffuse reflection metal strip in the corresponding first diffuse reflection region.

[0012] As a possible implementation manner, the repeating period of the second diffuse reflection metal strip in the second diffuse reflection region is twice the repeating period of the first diffuse reflection metal strip in the corresponding first diffuse reflection region.

[0013] As a possible implementation manner, the first diffuse reflection metal strip and the second diffuse reflection metal strip are both straight line structures with arrows at both ends.

[0014] As a possible implementation manner, the circularly polarized antenna body is a circularly polarized antenna body configured with a 90° one-to-two power divider and a one-to-four feeding network.

[0015] As a possible implementation manner, the circularly polarized antenna body comprises, in order from the direction close to the second diffuse reflection layer to the direction away from the second diffuse reflection layer, a parasitic patch layer, a driven patch layer, a first metal ground, a 90° one-to-two power divider, a second metal ground, and a one-to-four feeding network.

[0016] The parasitic patch layer is coupled with the driving patch layer and connected with the 90-degree one-to-two power divider, and the 90-degree one-to-two power divider is fed by the one-to-four feeding network.

[0017] In a second aspect, the application provides an integrated method for manufacturing the circularly polarized antenna based on the multi-modal frequency selective surface in the first aspect, which comprises the following steps:

[0018] A circularly polarized antenna body is provided, which comprises, from top to bottom, a parasitic patch layer, a driving patch layer, a first metal ground, a 90-degree one-to-two power divider, a second metal ground, and a one-to-four feeding network.

[0019] An absorbing layer is manufactured, a dielectric substrate is provided, which comprises opposite first and second surfaces, a first metal strip is etched on the first surface, and a second metal strip is etched on the second surface; the first and second metal strips are perpendicular but not intersected, and a patch resistor is arranged at the perpendicular point of the first and second metal strips;

[0020] A first diffuse reflection layer is manufactured, a dielectric substrate is provided, which comprises opposite first and second surfaces, and the first surface is opposite to the absorbing layer; a plurality of first diffuse reflection regions are formed on the first surface; a first diffuse reflection metal strip arranged in a regular matrix is etched in each first diffuse reflection region; the first diffuse reflection metal strips in the same first diffuse reflection region have consistent inclination directions; the first diffuse reflection metal strips in adjacent first diffuse reflection regions are symmetrically arranged with adjacent edges as the symmetric axes;

[0021] A second diffuse reflection layer is manufactured, a dielectric substrate is provided, which comprises opposite first and second surfaces, and the first surface is opposite to the first diffuse reflection layer; a plurality of second diffuse reflection regions are formed on the first surface, the number and area of the second diffuse reflection regions are the same as those of the first diffuse reflection regions, and one first diffuse reflection region corresponds to one second diffuse reflection region in space; a second diffuse reflection metal strip arranged in a regular matrix is arranged in each second diffuse reflection region, and the inclination direction of the second diffuse reflection metal strip is perpendicular to the inclination direction of the first diffuse reflection metal strip in the corresponding first diffuse reflection region;

[0022] The absorbing layer, the first diffuse reflection layer, and the second diffuse reflection layer are integrated on the circularly polarized antenna body from top to bottom.

[0023] In a third aspect, the application further provides a terminal applying the circularly polarized antenna based on the multi-modal frequency selective surface in the first aspect.

[0024] Compared with the prior art, the application has the following beneficial effects:

[0025] 1. The circularly polarized antenna based on the multi-modal frequency selective surface provided by the present application, the circularly polarized antenna provided by the present application, the wave-absorbing layer of which can absorb low-frequency electromagnetic waves in the incident electromagnetic waves, and the wave-absorbing layer has high transmissivity to the incident electromagnetic waves in the medium-high frequency band, so that the incident electromagnetic waves in the medium-high frequency band can penetrate the wave-absorbing layer to reach the first diffuse reflection layer or the second diffuse reflection layer, and the first diffuse reflection layer and the second diffuse reflection layer can diffuse the incident electromagnetic waves in the respective diffuse reflection frequency bands in different directions, achieving a better stealth effect.

[0026] 2. The circularly polarized antenna based on the multi-modal frequency selective surface provided by the present application, the working frequency band of the circularly polarized antenna body itself does not intersect or overlap with the wave-absorbing frequency band, the first diffuse reflection frequency band and the second diffuse reflection frequency band, and will not affect the transmission of electromagnetic waves in the antenna working frequency band, so as to ensure the S, C, X and Ku band ultra-wideband stealth, and will not affect the radiation efficiency in the antenna working band.

[0027] 3. The circularly polarized antenna based on the multi-modal frequency selective surface provided by the present application, the absorption, transmission and scattering modes are embedded in the multi-modal frequency selective surface, and the independent regulation and control of each mode can be realized.

[0028] 4. The circularly polarized antenna based on the multi-modal frequency selective surface provided by the present application, the combination design of 90° one-to-two power divider and one-to-four feeding network is adopted, so that a smaller axial ratio can be obtained, thereby improving the circular polarization performance of the antenna, and the present application is more modularized in adjustment and control, and provides more possibilities for the application of multi-frequency band, wide bandwidth, low loss and the like.

[0029] 5. The circularly polarized antenna based on the multi-modal frequency selective surface provided by the present application, the RCS suppression performance is very outstanding under different polarization conditions or under different incident angles. It not only realizes significant RCS reduction in the target working frequency band, but also can adapt to the electromagnetic wave environment of multiple angles and multiple polarizations, and embodies the multifunctionality and wide application potential of the structure. It has important significance in space exploration, radar system and multi-frequency band stealth platform and various scenes. BRIEF DESCRIPTION OF DRAWINGS

[0030] The accompanying drawings described herein are used to provide a further understanding of the present application, and constitute a part of the present application. The schematic embodiments of the present application and the descriptions thereof are used to explain the present application, and do not constitute an improper limitation on the present application. In the drawings:

[0031] Figure 1 and Figure 2 is a structure schematic diagram of the circularly polarized antenna based on the multi-modal frequency selective surface in the embodiments of the present application;

[0032] Figure 3A schematic view of the arrangement of the first diffusely reflective metal strips in each first diffusely reflective region in the embodiment of the present application;

[0033] Figure 4 A schematic view of the arrangement of the second diffusely reflective metal strips in the second diffusely reflective region in the embodiment of the present application, in which the repeat period of the second diffusely reflective metal strips is twice that of the first diffusely reflective metal strips in the corresponding first diffusely reflective region;

[0034] Figure 5 A schematic view of the structure of the wave-absorbing layer in the embodiment of the present application;

[0035] Figure 6 A simulation result graph of the wave-absorbing layer in the embodiment of the present application;

[0036] Figure 7 A schematic view of the structure of the double-layer diffusely reflective layer in the embodiment of the present application;

[0037] Figure 8 A simulation result graph of the diffusely reflective layer in the embodiment of the present application;

[0038] Figure 9 A schematic view of the structure of the circularly polarized antenna body in the embodiment of the present application;

[0039] Figure 10 A simulation result graph of the axial ratio and standing wave ratio of the circularly polarized antenna body in the embodiment of the present application;

[0040] Figure 11 A simulation result graph of the axial ratio and standing wave ratio of the circularly polarized antenna based on the multi-modal frequency selection surface in the embodiment of the present application;

[0041] Figure 12 A simulation result graph of the gain of the circularly polarized antenna based on the multi-modal frequency selection surface in the embodiment of the present application;

[0042] Figure 13 An exploded view of the 8x8 array structure of the circularly polarized antenna based on the multi-modal frequency selection surface in the embodiment of the present application;

[0043] Figure 14 A simulation result graph of the axial ratio and standing wave ratio of the 8x8 array structure of the circularly polarized antenna based on the multi-modal frequency selection surface in the embodiment of the present application;

[0044] Figure 15 A simulation result graph of the gain of the 8x8 array structure of the circularly polarized antenna based on the multi-modal frequency selection surface in the embodiment of the present application;

[0045] Figure 16 A simulation result graph of the RCS reduction of the 8x8 array structure of the circularly polarized antenna based on the multi-modal frequency selection surface in the embodiment of the present application under TE polarization;

[0046] Figure 17A simulation result diagram of RCS reduction of the 8x8 array structure of the circularly polarized antenna based on the multi-modal frequency selection surface in the embodiment of the present application under TM polarization.

[0047] Reference signs

[0048] 1-wave absorbing layer, 10-dielectric substrate, 100-first metal strip, 101-second metal strip, 102-patch resistor, 2-first diffuse reflection layer, 20-first diffuse reflection metal strip, 3-second diffuse reflection layer, 30-second diffuse reflection metal strip, 4-circularly polarized antenna body, 40-90° one-to-two power divider, 41-one-to-four feeding network, 42-parasitic patch layer, 43-driven patch layer, 44-first metal ground, 45-second metal ground, 5-metal ground plate. DETAILED DESCRIPTION

[0049] In order to clearly describe the technical solutions of the embodiments of the present application, in the embodiments of the present application, the words "first", "second" and the like are used to distinguish the same or similar items or items with basically the same function and effect. For example, the first threshold and the second threshold are only used to distinguish different thresholds, and do not limit the order. Those skilled in the art can understand that the words "first", "second" and the like do not limit the number and execution order, and the words "first", "second" and the like do not necessarily mean different.

[0050] It should be noted that in the present application, the words "exemplary" or "for example" are used to represent as an example, illustration or description. Any embodiment or design scheme described as "exemplary" or "for example" in the present application should not be interpreted as more preferred or more advantageous than other embodiments or design schemes. Rather, the words "exemplary" or "for example" are intended to present the relevant concept in a specific manner.

[0051] In the present application, "at least one" means one or more, and "multiple" means two or more. The association relationship of the associated objects is described, which means that there can be three kinds of relationships, for example, A and / or B, which can represent the following cases: A exists alone, A and B exist together, and B exists alone, where A and B can be singular or plural. The character " / " generally represents an "or" relationship between the associated objects before and after it. The following at least one (or similar expressions) means any combination of these items, including any combination of single item (or multiple items). For example, at least one of a, b or c can represent: a, b, c, the combination of a and b, the combination of a and c, the combination of b and c, or the combination of a, b and c, where a, b and c can be single or multiple.

[0052] The embodiment of the present application provides a circularly polarized antenna based on a multi-modal frequency selective surface, an integrated method and a terminal.

[0053] In a first aspect, the present application provides a circularly polarized antenna based on a multi-modal frequency selective surface, referring to Figure 1 The circularly polarized antenna body 4 is sequentially integrated with the wave-absorbing layer 1, the first diffuse reflection layer 2 and the second diffuse reflection layer 3 from top to bottom.

[0054] Referring to Figure 1 As a possible implementation manner, the wave-absorbing layer 1 comprises a dielectric substrate 10, and the shape of the dielectric substrate 10 is not limited, and the dielectric substrate 10 can be a square dielectric substrate or a rectangular dielectric substrate. The embodiment of the present application takes the rectangular dielectric substrate as an example for description. The dielectric substrate 10 comprises opposite first and second surfaces, the first surface is formed with a first metal strip 100, the first metal strip 100 is a first curved metal strip and is formed on a first diagonal line of the rectangular dielectric substrate, and the second surface is formed with a second metal strip 101, the second metal strip 101 is a second curved metal strip and is formed on a second diagonal line of the rectangular dielectric substrate. The first metal strip 100 and the second metal strip 101 are perpendicular but do not intersect, and a chip resistor 102 is arranged at the perpendicular point of the first metal strip 100 and the second metal strip 101. In this way, the overlap of the two chip resistors 102 can be avoided, and the polarization insensitivity of the surface of the wave-absorbing layer can also be realized due to the symmetry of the two metal strip patterns. In actual application, the first curved metal strip and the second curved metal strip constitute a resonator, and the first diffuse reflection layer 2 can be used as a full reflection metal surface, and the wave-absorbing layer and the first diffuse reflection layer 2 together constitute an artificial electromagnetic frequency selective surface. When the incident electromagnetic wave of a low frequency band passes through the wave-absorbing layer, the resonator resonates to form a circuit, and the current passes through the chip resistor 102, so that the energy is converted into heat and dissipated into the air, thereby realizing the absorption of the incident electromagnetic wave of the low frequency band.

[0055] The circularly polarized antenna body 4 has a working frequency band, the wave absorbing layer 1 has a wave absorbing frequency band, the first diffuse reflection layer 2 has a first diffuse reflection frequency band, and the second diffuse reflection layer 3 has a second diffuse reflection frequency band; the working frequency band does not intersect or overlap with the wave absorbing frequency band, the first diffuse reflection frequency band and the second diffuse reflection frequency band. Exemplarily, the wave absorbing frequency band is 2-6 GHz, the first diffuse reflection frequency band is 7-13 GHz, the second diffuse reflection frequency band is 16-22 GHz, and the working frequency band is 14-15 GHz. The first diffuse reflection frequency band is lower than the working frequency band, and the second diffuse reflection frequency band is higher than the working frequency band. When the incident electromagnetic wave is in the working frequency band, the wave absorbing layer 1 has high efficient electromagnetic wave transmission characteristics and almost does not affect the electromagnetic wave transmission in the frequency band, so that the entire structure of the application does not interfere with the electromagnetic wave radiated by the antenna, so that the electromagnetic wave can completely penetrate and does not affect the radiation performance of the antenna.

[0056] Referring to Figures 1-2 , as a possible implementation manner, the first diffuse reflection layer 2 has opposite first and second faces, and the first face is opposite to the wave absorbing layer 1; the first face is divided to form a plurality of first diffuse reflection regions; a first diffuse reflection metal strip 20 arranged in a regular matrix is arranged in each first diffuse reflection region; the first diffuse reflection metal strips 20 in the same first diffuse reflection region are consistent in the inclined direction; and the first diffuse reflection metal strips 20 in adjacent first diffuse reflection regions are symmetrically arranged with adjacent edges as the axis of symmetry.

[0057] Referring to Figures 1-3 , as an example, the first face of the first diffuse reflection layer 2 is divided to form four first diffuse reflection regions a1, a2, a3 and a4, and a first diffuse reflection metal strip 20 arranged in a regular matrix is arranged in each first diffuse reflection region.

[0058] Exemplarily, referring to Figure 3 (1), one first diffuse reflection metal strip 20 is arranged in each first diffuse reflection region, and the first diffuse reflection metal strips 20 in adjacent first diffuse reflection regions are symmetrically arranged with adjacent edges as the axis of symmetry, for example, the first diffuse reflection metal strips 20 in the a1 and a2 regions are symmetrically arranged with the adjacent edge L2 as the axis of symmetry, and the first diffuse reflection metal strips 20 in the a1 and a3 regions are symmetrically arranged with the adjacent edge L1 as the axis of symmetry.

[0059] Exemplarily, referring to Figure 3(2) two first diffuse reflection metal strips 20 are arranged in each first diffuse reflection region, the inclination direction of the two first diffuse reflection metal strips 20 in the same first diffuse reflection region is consistent, and the first diffuse reflection metal strips 20 in adjacent first diffuse reflection regions are symmetrically arranged with the adjacent side as the axis of symmetry, for example, the two first diffuse reflection metal strips 20 in the a1 and a2 regions are symmetrically arranged with the adjacent side L4 as the axis of symmetry, and the two first diffuse reflection metal strips 20 in the a1 and a3 regions are symmetrically arranged with the adjacent side L3 as the axis of symmetry.

[0060] Referring to Figures 1-2 , as a possible implementation, the second diffuse reflection layer 3 has opposite first and second surfaces, the first surface is opposite to the first diffuse reflection layer 2; the first surface is divided to form a plurality of second diffuse reflection regions, the second diffuse reflection regions are equal in number and area to the first diffuse reflection regions, and one first diffuse reflection region corresponds to one second diffuse reflection region in space; a second diffuse reflection metal strip 30 arranged in a regular matrix is arranged in each second diffuse reflection region, and the inclination direction of the second diffuse reflection metal strip 30 is perpendicular to the inclination direction of the first diffuse reflection metal strip 20 in the corresponding first diffuse reflection region.

[0061] Referring to Figures 1-4 , as an example, the first surface of the second diffuse reflection layer 3 is divided to form four second diffuse reflection regions b1, b2, b3 and b4, the regions b1 and a1, b2 and a2, b3 and a3, and b4 and a4 correspond to each other in space and are equal in area respectively; referring to Figure 4 (2), a second diffuse reflection metal strip 30 arranged in a regular matrix is arranged in each second diffuse reflection region, and the inclination direction of the second diffuse reflection metal strip 30 is perpendicular to the inclination direction of the first diffuse reflection metal strip 20 in the corresponding Figure 4 (1) of the first diffuse reflection region.

[0062] Referring to Figure 4 , as a possible implementation, the repetition period of the second diffuse reflection metal strip 30 in the second diffuse reflection region is twice the repetition period of the first diffuse reflection metal strip 20 in the corresponding first diffuse reflection region; that is, if the repetition period of the first diffuse reflection metal strip 20 in the first diffuse reflection region is n x n, then the repetition period of the second diffuse reflection metal strip 30 in the second diffuse reflection region corresponding to the first diffuse reflection region is 2n x 2n. Exemplarily, referring to Figure 4 (1), the repetition period of the first diffuse reflection metal strip 20 in the first diffuse reflection region a1 is 1 x 1 in the horizontal and vertical directions, and then the repetition period of the second diffuse reflection metal strip 30 in the second diffuse reflection region b1 corresponding to the first diffuse reflection region a1 is 2 x 2, that is, 4.

[0063] Referring to Figure 2As a possible implementation manner, the first diffused reflection metal strip 20 and the second diffused reflection metal strip 30 are both straight line structures with arrows at both ends. Exemplarily, two edges of the arrow are perpendicular, and the first diffused reflection metal strip 20 and the second diffused reflection metal strip 30 can be respectively arranged on the first surface of the two diffused reflection layers in a manner of etching, printing or the like.

[0064] The circularly polarized antenna provided by the application can absorb low-frequency electromagnetic waves in the incident electromagnetic waves, and has high transmissivity to incident electromagnetic waves in the medium-high frequency band, so that the incident electromagnetic waves in the medium-high frequency band can penetrate the wave-absorbing layer to reach the first diffused reflection layer or the second diffused reflection layer. The first diffused reflection layer and the second diffused reflection layer can diffusely reflect incident electromagnetic waves in the respective diffused reflection frequency bands in different directions, achieving a better stealth effect. Moreover, the working frequency band of the circularly polarized antenna body itself does not cross or overlap with the wave-absorbing frequency band, the first diffused reflection frequency band and the second diffused reflection frequency band, that is, the electromagnetic waves in the working frequency band of the antenna will not be affected by penetration, and the radiation efficiency in the working band of the antenna will not be affected. In the high frequency band, the second diffused reflection layer exhibits a polarization conversion characteristic to the incident electromagnetic waves, so that the energy of the incident electromagnetic waves is dispersed in all directions, thereby suppressing the back reflection performance, forming a high-frequency diffused reflection frequency band, and realizing electromagnetic stealth.

[0065] Referring to Figure 2 As a possible implementation manner, the circularly polarized antenna body 4 is a circularly polarized antenna body configured with a 90° one-to-two power divider 40 and a one-to-four feeding network 41. The circularly polarized antenna based on the multi-modal frequency selection surface provided by the application adjusts the phase difference by changing the line length through the 90° one-to-two power divider, thereby realizing wideband circular polarization. Compared with the prior art of realizing circular polarization by cutting corners on a square patch, the application is more convenient for adjusting the working frequency band of the antenna, such as the axial ratio and the standing wave ratio, so that the circular polarization performance is better. The application does not need to cut the patch, and the design is simple and the processing technology is easier to realize, thereby greatly reducing the manufacturing cost and the process difficulty.

[0066] Exemplarily, referring to Figures 1-2 As a possible implementation manner, the circularly polarized antenna body 4 includes, in order from the direction close to the second diffused reflection layer 3 to the direction away from the second diffused reflection layer 3, a parasitic patch layer 42, a driven patch layer 43, a first metal ground 44, a 90° one-to-two power divider 40, a second metal ground 45 and a one-to-four feeding network 41. The parasitic patch layer 42 and the driven patch layer 43 are both square, but the side lengths of the two squares are different. Preferably, the side length of the driven patch layer 43 is greater than the side length of the parasitic patch layer 42.

[0067] The application sequentially rotates and arranges single 90° one-to-two power dividers, combines a one-to-four feeding network, feeds a circularly polarized antenna body, and jointly forms a modal radiation stealth integrated broadband low RCS circularly polarized antenna unit structure with a wave absorbing layer and two layers of diffuse reflection layers. The combination design of the 90° one-to-two power dividers and the one-to-four feeding network can obtain a smaller axial ratio, thereby improving the circular polarization performance of the antenna, making the application more modularized in adjustment and control, and providing more possibilities for the application of multi-frequency, wide bandwidth, low loss and other requirements.

[0068] The technical solutions of the application will be further described in combination with specific embodiments.

[0069] Referring to Figure 5 A wave absorbing layer structure schematic diagram is provided for the embodiment. In order to observe the energy absorption characteristics of the wave absorbing layer to the incident electromagnetic wave, a metal floor 5 is loaded at a distance h from the wave absorbing layer 1 in the embodiment. In actual design, the metal floor 5 can also be replaced by other structures capable of exhibiting total reflection characteristics. The wave absorbing layer 1 and the metal floor 5 are separated by an air cavity with a height h. According to the quarter wavelength transformation theory, in order to achieve optimal energy absorption performance, h is one quarter of the wavelength corresponding to the center frequency of the absorption frequency band in the embodiment, that is, h = 18 mm. The dielectric substrate 10 of the wave absorbing layer 1 adopts Rogers RO5880 medium with a thickness t = 0.5 mm, a relative dielectric constant ε r = 2.2, and a loss tangent tanδ = 0.0009. The first metal strip 100 and the second metal strip 101 are two orthogonal dipole antennas which are miniaturized by multiple bending. The first metal strip 100 and the second metal strip 101 are printed on the top surface and the bottom surface of the dielectric substrate 10 respectively, and the patch resistance 102 is a patch resistance with a resistance R = 250Ω. Figure 5 Other parameter settings in the embodiment are as follows: unit period p = 25 mm, l1 = 2 mm, l2 = 1.2 mm, l3 = 1 mm, l4 = 3 mm, and w = 0.5 mm.

[0070] Next, the wave absorbing layer structure is simulated and verified. Periodic boundary conditions and Floquet ports in ANSYS HFSS full-wave simulation software are used for excitation. The reflection coefficient and the transmission coefficient of the wave absorbing layer are as shown in Figure 6 From the simulation results, it can be seen that when the metal floor is loaded, the wave absorbing layer has two resonance points fl1 = 3.06 GHz and fl2 = 6.08 GHz in the low frequency band, and S 11 <-10 dB in the frequency band of 2.53-6.64 GHz, and the relative bandwidth is 89.6%, which exhibits good electromagnetic wave absorption performance in the low frequency band. When the metal floor is not loaded, the wave absorbing layer has S 11Close to 0dB, that is, the transmission coefficient is approximately 1, has good electromagnetic wave transmission performance. Based on this, the metal floor can be replaced by an electromagnetic surface with full reflection characteristics in the low frequency band, which will not affect the absorption characteristics of the wave-absorbing layer in the low frequency band, and will not affect the other electromagnetic characteristics of the bottom electromagnetic surface due to the high transmission characteristics of the wave-absorbing layer in the medium and high frequency band, which is more conducive to the design of the ultra-wideband structure.

[0071] Referring to Figure 7 The structure schematic diagram of the first diffuse reflection layer 2 and the second diffuse reflection layer 3 provided for the embodiment, the first diffuse reflection metal strip 20 and the second diffuse reflection metal strip 30 are attached on the Rogers RO5880 dielectric plate with relative permittivity ε r = 2.2 and loss tangent tan δ = 0.0009, and the thickness of the dielectric plate is 0.254 mm. The unit period is p / 2 = 6.25 mm, and the repeat period of the double-arrow of the second diffuse reflection layer is twice the repeat period of the double-arrow of the first diffuse reflection layer. Figure 7 Other parameter settings are as follows: L t = 9.5 mm, L t1 = 2.5 mm, w t = 0.5 mm, L b = 2.3 mm, L b1 = 3 mm, w b = 0.8 mm. The double-arrow structure of the diffuse reflection metal can be regarded as a combination of a slant V-shaped resonator and a tangent resonator. Defining the direction parallel to the tangent resonator as the v-axis, and the direction perpendicular to the v-axis in the xoy plane as the u-axis, the resonant mode supported by a single slant V-shaped resonator is excited by the electric field component along the v-axis and the u-axis, respectively, and the multimode dipole resonant mode supported by a single tangent resonator is excited by the electric field component along the v-axis. Only discussing a single double-arrow metal strip, in the case of v-polarization, the V-shaped resonator can be regarded as evolved from the tangent resonator, and the whole double-arrow plays the role of extending the tangent resonator. The extended tangent resonator is coupled with the metal floor, and then electromagnetic resonance is excited. In the case of u-polarization, the V-shaped resonator is equivalent to a tangent resonator, and the coupling between the V-shaped resonator and the metal floor produces a surface current, and then electromagnetic resonance is produced. Therefore, changing the geometric parameters of the double-arrow can change the resonant frequency, and then an ultra-wideband diffuse reflection layer is obtained. Moreover, the double-arrow structure can also convert normally incident x-polarized waves into y-polarized reflected waves, with high conversion efficiency.

[0072] In order to verify the characteristics of the double diffuse reflection layer, the full-wave simulation software Ansys HFSS is used to simulate the diffuse reflection layer structure, the double diffuse reflection layer is arranged periodically along the x-axis and the y-axis, and the corresponding Floquet port is single-port incident, and the simulation results are as follows Figure 8The black square dotted line is the reflection coefficient |S 11 |, which indicates that when the polarization direction of the incident wave is along the x-axis direction and the y-axis direction, strong cross-polarization reflection occurs, that is, after the incident wave along the x-polarization direction irradiates the double-headed arrow diffuse reflection layer, the polarization direction is changed to the y-direction and reflects back, as shown by the black square dotted line in Figure 8 12 |S 12 |, and the structure cross-polarization reflection band is wide, and resonance points are generated at 6.1 GHz, 11.0 GHz and 19.5 GHz, respectively, and the polarization conversion efficiency is close to 100% at the three frequency points. |S 11 |<-10dB, the cross-polarization reflection band of the x-polarization and y-polarization incident wave extends from 4.9 GHz to 22 GHz, and the electromagnetic wave energy is converted in the ultra-wide frequency band.

[0073] Referring to Figure 9 , the structure schematic diagram of the circularly polarized antenna body 4 provided in the embodiment, the unit period is p / 2=6.25mm, and the medium plates used are Rogers RO5880 medium plates with a relative dielectric constant ε r =2.2 and a loss tangent tanδ=0.0009. The circularly polarized antenna body 4 is arranged alternately with metal and medium, the uppermost layer is a parasitic patch layer 42, which is not directly connected to the feeding system, but interacts with the driven patch layer 43 through coupling, so as to enhance the bandwidth and gain of the antenna. The driven patch layer 43 and the parasitic patch layer 42 are separated by a medium plate a with a thickness of 1mm. The driven patch layer 43 is a patch directly connected to the feeding system, which is responsible for transmitting and receiving signals. The size of the driven patch layer 43 can determine the basic performance of the antenna, such as operating frequency, gain and radiation mode. The metal plate b between the driven patch layer 43 and the first metal ground 44 has a thickness of 1mm, and the lowermost layer of the circularly polarized antenna is a metal reflector, which can improve the gain and directivity of the antenna and reduce the back radiation.

[0074] At the same time, there are two groups of blind holes, the first group of blind holes are used to punch through the medium plates between the driven patch layer 43 and the first metal ground 44 and between the first metal ground 44 and the one-to-four feeding network 41, which are used for waveguide ports to feed the driven patch layer 43 through a strip line; the second group of blind holes punch through the medium layer between the first metal ground 44 and the second metal ground 45, in order to realize the mutual interference between the two feeding ports and reduce the electromagnetic coupling between the two feeding ports. The two waveguide ports can feed the electric field in different directions of the antenna respectively, so that there is a phase difference of 90° between the two orthogonal electric fields, realizing circular polarization. Figure 9 The parameters of the circularly polarized antenna body in the embodiment are as follows: the side length L top= 3.8mm, side length L of the driving patch layer 43 btm = 6.2mm, diameter g of the circular hole on the first metal ground 44 r = 0.75mm, diameter p of the first group of blind holes r = 0.25mm, length d of the one-to-four feeding network 41 f = 1.4mm, distance d between the first group of blind holes and the second group of blind holes f1 = 0.7mm, diameter p of the second group of blind holes r1 = 0.15mm.

[0075] The simulation tool Ansys HFSS2021 is used to simulate the circularly polarized antenna body, and the radiation boundary condition is adopted to obtain the simulation results of the standing wave ratio and the axial ratio of the circularly polarized antenna body as shown in Figure 10 . Among them, the VSWR is less than 2:1 in the range of 13.1 to 14.5GHz, and the axial ratio of the circularly polarized antenna body is less than 3dB in the entire working frequency band of the antenna. The driving patch layer works in the first frequency domain with the smallest axial ratio, and the parasitic patch layer works in the second frequency domain with the smallest axial ratio, and the two interact to achieve wideband circular polarization.

[0076] Next, the wave-absorbing layer, the two diffuse reflection layers, and the circularly polarized antenna body are combined, and the Ansys HFSS2021 is used to simulate the combined antenna unit, and the radiation boundary condition and the waveguide port feeding are adopted. The simulation results of the axial ratio and the standing wave ratio of the antenna are shown in Figure 11 , wherein the standing wave ratio is less than 2 in the working band 13-15GHz, and the axial ratio is less than 3dB, which has very good circular polarization performance.

[0077] Figure 12 The gain values of right-handed circular polarization (RHCP) and left-handed circular polarization (LHCP) are shown, and the LHCP gain remains at a high level (about 10dB) in the entire frequency band. The antenna mainly produces left-handed circular polarization in this frequency band.

[0078] Referring to Figure 13 , an exploded view of a circularly polarized antenna 8x8 array structure based on a multi-modal frequency selective surface is shown. The array structure is composed of 8x8, i.e. 64 circularly polarized antennas based on a multi-modal frequency selective surface, and the array structure has a size of 100mmx100mm. A one-to-two power divider and a one-to-sixty-four feeding network are loaded in sequence with a rotation of 90°, and a coaxial feeding form is adopted to realize unified feeding of the entire antenna array. The coaxial feeding has the characteristics of simple structure, low loss, good impedance matching, excellent shielding performance, which can reduce the reflection loss, improve the transmission efficiency of the antenna, and has high adaptability.

[0079] The circularly polarized antenna array structure based on a multimode frequency selective surface consists of, from top to bottom, an absorbing layer, a polarization conversion metasurface layer, a parasitic patch layer, a driving patch layer, a 90° 1-to-2 power divider, and a 1-to-64 feed network. It is particularly important to note that, to ensure good diffuse reflection performance, the polarization conversion metasurface is not obtained by translating a multimode radiation stealth integrated broadband low RCS circularly polarized antenna element. Instead, the double-headed arrow layer in that antenna element is replaced with a single-layer element structure with arrows pointing in the same direction, ensuring that the arrows of the two layers are perpendicular to each other along the positive z-direction. This structure is then assembled into a 4×4 subarray, and the subarrays are rotated three times sequentially to form an 8×8 circularly polarized antenna array structure based on a multimode frequency selective surface.

[0080] Will Figure 13 The 8×8 array structure of the circularly polarized antenna based on a multimode frequency selective surface, as shown, was simulated using CST with full-wave performance. The results are as follows: Figure 14 and Figure 15 As shown. Within the antenna's operating frequency band of 13.0–15.0 GHz, the antenna axial ratio (AR) is less than 3 dB. The designed 8×8 array structure exhibits excellent circular polarization performance, approaching an ideal circular polarization state, and can effectively transmit and receive circularly polarized electromagnetic waves at various angles. Within the antenna's operating frequency band of 12.8–15.4 GHz, the VSWR is <1.8, meeting the project's requirements. The antenna impedance matching is good, and the transmission efficiency is extremely high.

[0081] The RCS reduction value of an antenna is an important criterion for measuring its stealth performance. The simulation results of the RCS reduction value of the designed 8×8 array structure are as follows: Figure 16 and Figure 17 As shown, both TE and TM polarization exhibit excellent RCS suppression within the 13–15 GHz operating frequency band at different incident angles (0° to 20°), with suppression levels consistently above 10 dB. This demonstrates that the designed 8×8 array structure can significantly reduce the radar cross-section of the target within the antenna's main operating frequency band, achieving electromagnetic stealth. Our designed structure demonstrates outstanding RCS suppression performance under different polarization conditions and at different incident angles. It not only achieves significant RCS reduction within the target's operating frequency band but also adapts to multi-angle and multi-polarization electromagnetic wave environments, showcasing the structure's versatility and broad application potential. Especially for applications with extremely high stealth requirements, such as spaceborne array antennas, our structural design demonstrates powerful RCS reduction capabilities, effectively reducing radar detectability while maintaining antenna radiation performance, representing a significant breakthrough in the field of stealth antennas.

[0082] In a second aspect, the present application provides an integration method for manufacturing the circularly polarized antenna based on the multi-modal frequency selective surface provided in the first aspect, the integration method comprising the following steps:

[0083] A circularly polarized antenna body is provided, which comprises, from top to bottom, a parasitic patch layer, a driven patch layer, a first metal ground, a 90-degree one-to-two power divider, a second metal ground, and a one-to-four feeding network.

[0084] An absorbing layer is manufactured, a dielectric substrate is provided, which comprises opposite first and second surfaces, a first metal strip is etched on the first surface, and a second metal strip is etched on the second surface; the first and second metal strips are perpendicular but do not intersect, and a patch resistor is arranged at the perpendicular point of the first and second metal strips;

[0085] A first diffuse reflection layer is manufactured, a dielectric substrate is provided, which has opposite first and second surfaces, and the first surface is opposite to the absorbing layer; a plurality of first diffuse reflection regions are divided on the first surface; a first diffuse reflection metal strip arranged in a regular matrix is etched in each first diffuse reflection region; the first diffuse reflection metal strips in the same first diffuse reflection region are consistent in the direction of inclination; and the first diffuse reflection metal strips in adjacent first diffuse reflection regions are symmetrically arranged with adjacent edges as the axis of symmetry.

[0086] A second diffuse reflection layer is manufactured, a dielectric substrate is provided, which has opposite first and second surfaces, and the first surface is opposite to the first diffuse reflection layer; a plurality of second diffuse reflection regions are divided on the first surface, the number and area of the second diffuse reflection regions are the same as those of the first diffuse reflection regions, and one first diffuse reflection region corresponds to one second diffuse reflection region in space; a second diffuse reflection metal strip arranged in a regular matrix is arranged in each second diffuse reflection region, and the direction of inclination of the second diffuse reflection metal strip is perpendicular to the direction of inclination of the first diffuse reflection metal strip in the corresponding first diffuse reflection region.

[0087] The absorbing layer, the first diffuse reflection layer, and the second diffuse reflection layer are integrated on the circularly polarized antenna body from top to bottom.

[0088] In a third aspect, the present application further provides a terminal applying the circularly polarized antenna based on the multi-modal frequency selective surface provided in the first aspect.

[0089] Although the present application has been described in connection with various embodiments thereof, it will be understood that the application is capable of further modifications and that this application is intended to cover any and all such variations, using the scope of the application, which is defined by the appended claims. In the description of the application, the term "comprising" does not exclude other components or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single processor or other unit can fulfill the functions of several items recited in the description. Certain measures can be implemented in different embodiments of the application, and these measures are not necessarily mutually exclusive.

[0090] Although the present application has been described in connection with specific features thereof, it will be evident to an artisan of ordinary skill that various modifications and changes can be made to the application without departing from the spirit and scope thereof. Accordingly, it is intended that the description and drawings be regarded as illustrative rather than restrictive. The scope of the application is indicated by the appended claims, rather than the foregoing description, and all changes that come within the meaning and range of equivalents thereof are intended to be embraced therein.

Claims

1. A circularly polarized antenna based on a multimode frequency selective surface, characterized in that, On the circularly polarized antenna body, an absorbing layer, a first diffuse reflection layer, and a second diffuse reflection layer are integrated sequentially from top to bottom; wherein, the circularly polarized antenna body has an operating frequency band, the absorbing layer has an absorbing frequency band, the first diffuse reflection layer has a first diffuse reflection frequency band, and the second diffuse reflection layer has a second diffuse reflection frequency band; the operating frequency band does not intersect or overlap with the absorbing frequency band, the first diffuse reflection frequency band, and the second diffuse reflection frequency band; The first diffuse reflection layer has a first surface and a second surface facing each other, with the first surface facing the absorbing layer; the first surface is divided into multiple first diffuse reflection regions; each first diffuse reflection region is provided with first diffuse reflection metal strips arranged in a regular matrix; the first diffuse reflection metal strips located in the same first diffuse reflection region have the same tilt direction; the first diffuse reflection metal strips in adjacent first diffuse reflection regions are symmetrically arranged with adjacent sides as the axis of symmetry. The second diffuse reflection layer has a first surface and a second surface facing each other, with the first surface facing the first diffuse reflection layer; the first surface is divided into multiple second diffuse reflection regions, the number of second diffuse reflection regions is the same as the number of first diffuse reflection regions, and the area is equal, with one first diffuse reflection region corresponding to one second diffuse reflection region in space; each second diffuse reflection region is provided with second diffuse reflection metal strips arranged in a regular matrix, and the tilt direction of the second diffuse reflection metal strips is perpendicular to the tilt direction of the first diffuse reflection metal strips in the corresponding first diffuse reflection region.

2. The circularly polarized antenna based on a multimode frequency selective surface according to claim 1, characterized in that, The absorbing layer includes a dielectric substrate, which includes a first surface and a second surface facing each other. A first metal strip is formed on the first surface, and a second metal strip is formed on the second surface. The first metal strip and the second metal strip are perpendicular but do not intersect. A chip resistor is disposed at the perpendicular point of the first metal strip and the second metal strip.

3. The circularly polarized antenna based on a multimode frequency selective surface according to claim 2, characterized in that, The dielectric substrate is a rectangular dielectric substrate, the first metal strip is a first curved metal strip formed on the first diagonal of the rectangular dielectric substrate; the second metal strip is a second curved metal strip formed on the second diagonal of the rectangular dielectric substrate.

4. The circularly polarized antenna based on a multimode frequency selective surface according to claim 1, characterized in that, The repetition period of the second diffuse reflection metal strip in the second diffuse reflection region is twice that of the repetition period of the first diffuse reflection metal strip in the corresponding first diffuse reflection region.

5. The circularly polarized antenna based on a multimode frequency selective surface according to claim 1, characterized in that, Both the first and second diffuse reflective metal strips are straight structures with arrows at both ends.

6. The circularly polarized antenna based on a multimode frequency selective surface according to claim 1, characterized in that, The circularly polarized antenna body is equipped with a 90° 1-to-2 power divider and a 1-to-4 feed network.

7. The circularly polarized antenna based on a multimode frequency selective surface according to claim 6, characterized in that, The circularly polarized antenna body includes, in sequence from the direction closest to the second diffuse reflection layer to the direction far from the second diffuse reflection layer, a parasitic patch layer, a driving patch layer, a first metal ground, a 90° 1-to-2 power divider, a second metal ground, and a 1-to-4 feed network. The parasitic patch layer is coupled to the driving patch layer and then connected to the 90° 1-to-2 power divider, which is powered by a 1-to-4 power feeder network.

8. An integration method for fabricating a circularly polarized antenna based on a multimode frequency selective surface as described in any one of claims 1 to 7, the integration method comprising the following steps: A circularly polarized antenna body is provided, which, from top to bottom, includes a parasitic patch layer, a driving patch layer, a first metal ground, a 90° 1-to-2 power divider, a second metal ground, and a 1-to-4 feed network. An absorber layer is fabricated, and a dielectric substrate is provided. The dielectric substrate includes a first surface and a second surface opposite to each other. A first metal strip is etched on the first surface, and a second metal strip is etched on the second surface. The first metal strip and the second metal strip are perpendicular but do not intersect. A chip resistor is disposed at each perpendicular point of the first metal strip and the second metal strip. A first diffuse reflection layer is fabricated, and a dielectric substrate is provided, the dielectric substrate having a first surface and a second surface opposite to each other, the first surface being opposite to the absorbing layer; a plurality of first diffuse reflection regions are formed on the first surface. Each of the first diffuse reflection regions is etched to form first diffuse reflection metal strips arranged in a regular matrix; the first diffuse reflection metal strips located in the same first diffuse reflection region have the same tilt direction; the first diffuse reflection metal strips in adjacent first diffuse reflection regions are symmetrically arranged with adjacent sides as the axis of symmetry; A second diffuse reflection layer is fabricated, and a dielectric substrate is provided. The dielectric substrate has a first surface and a second surface facing each other. The first surface is opposite to the first diffuse reflection layer. The first surface is divided into a plurality of second diffuse reflection regions. The number of second diffuse reflection regions is the same as that of the first diffuse reflection regions, and the areas are equal. One first diffuse reflection region corresponds to one second diffuse reflection region in space. Each second diffuse reflection region is provided with second diffuse reflection metal strips arranged in a regular matrix. The tilt direction of the second diffuse reflection metal strips is perpendicular to the tilt direction of the first diffuse reflection metal strips in the corresponding first diffuse reflection region. The absorption layer, the first diffuse reflection layer, and the second diffuse reflection layer are sequentially integrated onto the circularly polarized antenna body from top to bottom.

9. A terminal, characterized in that, The terminal uses the circularly polarized antenna based on a multimode frequency selective surface as described in any one of claims 1 to 7.

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