A compact low-frequency-ratio dual-band metasurface structure

Abstract

The application discloses a compact low-frequency ratio double-band metasurface structure, the metasurface is composed of a plurality of units with the same structure arranged periodically, each unit is composed of three layers of metal patches and two layers of dielectric layers, and a dielectric layer is arranged between each two adjacent metal patches, and specifically comprises: a top layer metal patch; a middle layer metal patch; a bottom layer metal patch; a first dielectric layer, which is arranged between the top layer metal patch and the middle layer metal patch; and a second dielectric layer, which is arranged between the middle layer metal patch and the bottom layer metal patch. The application has electromagnetic characteristics such as wide band, high wave transmission characteristic, out-of-band steep cutoff characteristic and polarization stability, and has a simple overall structure, light weight and easy processing, and has a wide application prospect in the fields of antennas, communication systems, electromagnetic countermeasures and military stealth.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of microwave waveband electromagnetic wave regulation, and particularly relates to a compact low-frequency ratio double-waveband metasurface structure. BACKGROUND

[0002] The metasurface refers to a two-dimensional array of sub-wavelength unit structures with specific geometric shapes arranged periodically or non-periodically, and the thickness is much smaller than the wavelength. The metasurface is generally divided into reflective metasurfaces and transmissive metasurfaces. The transmissive metasurface has the characteristics of in-band wave transmission and out-of-band cutoff, and is widely used in devices or systems such as stealth antenna covers, high-isolation antennas, spatial filters, and wireless communication. On the other hand, in order to meet the practical application requirements of conformal stealth and multi-waveband communication, the transmissive metasurface with the characteristics of low-frequency ratio, wide-band double-waveband wave transmission, large-angle stability, polarization insensitivity, low profile, and steep out-of-band cutoff has a wider application prospect. However, the traditional double-waveband metasurface or double-waveband frequency selection does not have the above characteristics.

[0003] The existing double-waveband metasurface cannot simultaneously have the characteristics of low-frequency ratio, steep cutoff, polarization insensitivity, large-angle stability, and low profile. Therefore, there is an urgent need for a double-waveband metasurface that simultaneously has the above excellent characteristics. SUMMARY

[0004] The purpose of the present application is to provide a compact low-frequency ratio double-waveband metasurface structure to overcome the deficiencies and shortcomings of the prior art.

[0005] To achieve the above purpose, the present application provides a compact low-frequency ratio double-waveband metasurface structure, which is composed of a plurality of unit structures arranged periodically, each unit structure is composed of three layers of metal patches and two layers of dielectric layers, and each adjacent two layers of metal patches are sandwiched by a layer of dielectric layer, specifically comprising: a top layer metal patch; a middle layer metal patch; a bottom layer metal patch; a first dielectric layer sandwiched between the top layer metal patch and the middle layer metal patch; and a second dielectric layer sandwiched between the middle layer metal patch and the bottom layer metal patch.

[0006] The period size of each unit structure is D x in the length direction of the x-axis, and D y in the width direction of the y-axis, and D x =D y .

[0007] Specifically, the top layer metal patch comprises: a top layer square ring with a square ring structure having a line width W1; and a Jerusalem cross structure arranged in the interior of the top layer square ring without contact, and the center of the Jerusalem cross structure coincides with the center of the top layer square ring.

[0008] Specifically, the Jerusalem cross structure comprises: main arms in a cross structure at the center, auxiliary arms connected perpendicularly with the end of the main arms respectively, and the length L2 of the main arm is greater than the length L3 of the auxiliary arm, and the width W2 of the main arm is less than the width W3 of the auxiliary arm.

[0009] The Jerusalem cross structure is equivalent to an LC series resonant circuit, and the top layer square ring is equivalent to an LC parallel resonant circuit.

[0010] The structure of the bottom layer metal patch is consistent with that of the top layer metal patch.

[0011] Specifically, the intermediate layer metal patch comprises: an intermediate layer square ring in a square ring structure with a line width W4; and a square patch arranged in the interior of the intermediate layer square ring without contact, and the center of the square patch coincides with the center of the intermediate layer square ring.

[0012] The dielectric constant of the first dielectric layer and the second dielectric layer is 4.5, the loss tangent angle is 0.0035, and the thickness is 1.5 mm.

[0013] By adjusting the line width W1 of the top layer square ring, the capacitance value of the LC parallel resonant circuit can be changed to realize the regulation and control of the C-band passband resonant frequency; by adjusting the length L2 of the main arm of the Jerusalem cross structure, the inductance value of the LC series resonant circuit can be changed to realize the regulation and control of the X-band passband resonant frequency, so that the metasurface has a low frequency ratio characteristic.

[0014] The Jerusalem cross structure, the top layer square ring, the square patch and the intermediate layer square ring all have rotational symmetry, so that the metasurface is not sensitive to the polarization of the incident electromagnetic wave, and has a polarization-insensitive characteristic.

[0015] Compared with the prior art, the present application has the following beneficial effects:

[0016] 1. The structure of the present application is symmetrical, has polarization stability, and is designed in a subwavelength size, and still has a very high transmission rate when a large angle of incidence.

[0017] 2. The present application generates electromagnetic resonance through the tight coupling between the metal patches of each layer to form two transmission passbands with a second-order bandpass filter response, the center frequencies of the two transmission passbands are similar, and the metasurface unit has a low frequency ratio and a wideband characteristic.

[0018] 3. The metasurface has a transmission zero point between the two transmission passbands, so that the metasurface has a steep cutoff characteristic.

[0019] 4、The application has wide application range, can be applied to radome to reduce radar scattering cross section, can be used for realizing communication, reducing mutual coupling between antenna array elements, and can be used for increasing antenna radiation, and therefore has wide application prospect in the fields of antenna, communication system, electromagnetic countermeasure and military stealth. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is a schematic diagram of a 10*10 array three-dimensional structure of the super surface of the application;

[0021] Figure 2 It is a schematic diagram of a top layer metal patch surface of the super surface unit of the application;

[0022] Figure 3 It is a schematic diagram of a middle layer metal patch surface of the super surface unit of the application;

[0023] Figure 4 It is a curve simulation diagram of TE polarization transmission coefficient and reflection coefficient of the super surface unit of the application;

[0024] Figure 5 It is a curve simulation diagram of TM polarization transmission coefficient and reflection coefficient of the super surface unit of the application;

[0025] Figure 6 It is a C waveband regulation simulation result of the super surface unit of the application;

[0026] Figure 7 It is an X waveband regulation simulation result of the super surface unit of the application;

[0027] Figure 8 It is a simulation result of transmission coefficient under different incident angles of the super surface unit of the application under TE polarization;

[0028] Figure 9 It is a simulation result of transmission coefficient under different incident angles of the super surface unit of the application under TM polarization. DETAILED DESCRIPTION

[0029] The technical content, structural features, purposes achieved and effects of the application will be described in detail below by preferred embodiments in combination with the drawings.

[0030] It should be noted that the drawings are very simplified and all use non-precise proportions, only for the purpose of conveniently and clearly assisting in the description of the embodiments of the application, and are not used to limit the application, and therefore do not have technical substantial significance, any modification of structure, change of proportional relationship or adjustment of size, without affecting the effects and purposes achieved by the application, should still fall within the scope covered by the disclosed technical content of the application.

[0031] It should be noted that in the present application, the relationship terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or sequence between the entities or operations. Moreover, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes the elements listed explicitly, but also includes other elements not listed explicitly, or further includes the elements inherent to such process, method, article or equipment.

[0032] The present application provides a compact low-frequency ratio double-band super surface structure, the super surface refers to a two-dimensional metamaterial with a thickness much smaller than the wavelength, which is widely used in devices or systems such as invisible antenna cover, high isolation antenna, spatial filter, wireless communication, etc. Figure 1 As shown in the figure, the super surface is composed of a plurality of units with the same structure arranged periodically, each unit is composed of three layers of metal patches and two layers of dielectric layers, and each adjacent two layers of metal patches are sandwiched with a layer of dielectric layer, and the double-band wave transmission is realized through the resonance between each layer of metal patch, and the wave transmission band is respectively in C band (frequency range is 4-8GHz) and X band (frequency range is 8-12GHz), and the period size of each unit is D x in the x-axis length direction, and D y in the y-axis width direction, and D x =D y . The metal patch includes: top layer metal patch 1, middle layer metal patch 3, bottom layer metal patch 5; the dielectric layer includes: first dielectric layer 2, second dielectric layer 4, and the first dielectric layer 2 plays a supporting role, sandwiched between the top layer metal patch 1 and the middle layer metal patch 3, the top layer metal patch 1 is attached to one side of the first dielectric layer 2, and the middle layer metal patch 3 is attached to the other side of the first dielectric layer 2; the second dielectric layer 4 plays a supporting role, sandwiched between the middle layer metal patch 3 and the bottom layer metal patch 5, the middle layer metal patch 3 is attached to one side of the second dielectric layer 4, and the bottom layer metal patch 5 is attached to the other side of the second dielectric layer 4.

[0033] Further, as shown in the figure, Figure 2 The top layer metal patch 1 is composed of Jerusalem cross structure (special cross structure composed of 4 T-shaped structures) 11 and top layer square ring 12, wherein the Jerusalem cross structure 11 is equivalent to LC series resonant circuit, and the top layer square ring 12 is equivalent to LC parallel resonant circuit, the top layer square ring 12 is a square ring structure with a certain width, and the ring width is recorded as line width W1, the outer side length L1 of the top layer square ring 12 is less than the unit period size D x , D yThe Jerusalem cross structure 11 is arranged inside the top layer square ring 12 without contact with the top layer square ring 12, and the center of the Jerusalem cross structure 11 coincides with the center of the top layer square ring 12. The Jerusalem cross structure 11 comprises main arms 111 in a cross structure at the center, and auxiliary arms 112 vertically connected to the ends of the main arms 111 respectively. The length L2 of the main arms 111 is greater than the length L3 of the auxiliary arms 112, and the width W2 of the main arms 111 is less than the width W3 of the auxiliary arms 112. By adjusting the line width W1 of the top layer square ring 12, the capacitance value of the LC parallel equivalent circuit can be changed, so as to flexibly control the C-band passband resonance frequency. By adjusting the length L2 of the main arms 111 of the Jerusalem cross structure 11, the inductance value of the LC series equivalent circuit can be changed, so as to flexibly control the X-band passband resonance frequency, thereby making the metasurface have the low frequency ratio characteristic of the passband.

[0034] Further, as shown in Figure 3 The intermediate layer metal patch 3 is composed of a square patch 31 and an intermediate layer square ring 32, and is equivalent to another LC parallel circuit. The intermediate layer square ring 32 is a square ring structure with a certain width, and the ring width is recorded as line width W4. The outer side length L4 of the intermediate layer square ring 32 is equal to the unit period size D x , D y ; the square patch 31 is arranged inside the intermediate layer square ring 32 without contact with the intermediate layer square ring 32, and the center of the square patch 31 coincides with the center of the intermediate layer square ring 32. The side length of the square patch 31 is L5.

[0035] The structure of the bottom layer metal patch 5 is consistent with that of the top layer metal patch 1, which will not be described in detail here.

[0036] Preferably, the metal used in the metal patch is copper foil, and the thickness of the copper foil is about 0.017 mm.

[0037] In the preferred embodiment, the period size D x of each unit in the x-axis length direction is 3.8 mm, and the period size D y in the y-axis width direction is 3.8 mm. The outer side length L1 of the top layer square ring 12 is 3.6 mm, and the line width W1 is 0.275 mm. The width W2 of the main arms 111 of the Jerusalem cross structure 11 is 0.1 mm, the width W3 of the auxiliary arms 112 is 0.3 mm, the length L2 of the main arms 111 is 2.4 mm, and the length L3 of the auxiliary arms 112 is 2.3 mm. The outer side length L5 of the square patch 31 is 2.8 mm, and the line width W4 of the intermediate layer square ring 32 is 0.35 mm.

[0038] In the preferred embodiment, the first dielectric layer 2 and the second dielectric layer 4 are both Arlon AD450, with a dielectric constant of 4.5, a loss tangent of 0.0035, and a dielectric thickness d = 1.5 mm.

[0039] Specifically, the Jerusalem cross structure 11, the top layer square ring 12, the square patch 31, and the middle layer square ring 32 are all symmetrical about the x-axis and the y-axis, so that the metasurface has rotational symmetry, is insensitive to the polarization of the incident electromagnetic wave, and has polarization-insensitive characteristics.

[0040] The metasurface has only two dielectric layers and does not introduce an air layer, so it has a low profile.

[0041] The tight coupling between the metal patches in each layer of the metasurface produces electromagnetic resonance, forming two transmission passbands with second-order bandpass filter responses, and the center frequencies of the two transmission passbands are similar, so that the metasurface has a low frequency ratio and wideband characteristics. There is a transmission zero point between the two transmission passbands, so that the metasurface has a steep cutoff characteristic.

[0042] As shown in Figure 4 , Figure 5 When a TE polarized electromagnetic wave or a TM polarized electromagnetic wave in the air is incident on one side of the metasurface, the metasurface produces a transmission passband with two transmission poles in the C band and the X band, respectively, forming a second-order bandpass filter response, i.e., the metasurface exhibits a second-order resonance characteristic, so that the metasurface has a wideband and high-transmission characteristic. For a TE polarized electromagnetic wave, the transmission loss is less than 3 dB in the frequency range of 6.05-8.42 GHz and 9.63-10.63 GHz, and for a TM polarized electromagnetic wave, the transmission loss is less than 3 dB in the frequency range of 6.08-8.40 GHz and 9.66-10.6 GHz. The relative bandwidth of the 3 dB passband for both polarized electromagnetic waves is more than 32% in the C band and more than 9.8% in the X band. The metasurface has a transmission zero point between the two transmission passbands, so that the metasurface has a steep cutoff characteristic outside the transmission band. The center frequency of the transmission band of the metasurface is 7.24 GHz in the C band and 10.13 GHz in the X band, and the frequency ratio of the center frequencies of the transmission bands is only 1.39, so the metasurface has a low frequency ratio characteristic.

[0043] As shown in Figure 6 , by adjusting the line width W1 of the top layer square ring 12, the C band passband resonance frequency is adjusted. When the line width W1 is 0.275 mm, 0.300 mm, and 0.325 mm, respectively, it is found that as the line width W1 increases, the C band passband resonance frequency shifts to a higher frequency, and the X band passband resonance frequency remains unchanged.

[0044] As shown in Figure 7As shown, by adjusting the length L2 of the main arm of the Jerusalem cross 11, the X-band passband resonance frequency is regulated. The length L2 of the main arm is respectively 2.50mm, 2.45mm, 2.40mm, and it is found that with the increase of the length L2 of the main arm, the X-band passband resonance frequency shifts to low frequency, and the C-band passband resonance frequency remains unchanged.

[0045] As shown in FIG. 6, for TE polarization, the metasurface has good double-band, high-transmission, and low-frequency characteristics in the incident angle range of 0°-60°. Figure 8 As shown in FIG. 6, for TE polarization, the metasurface has good double-band, high-transmission, and low-frequency characteristics in the incident angle range of 0°-60°.

[0046] As shown in FIG. 6, for TE polarization, the metasurface has good double-band, high-transmission, and low-frequency characteristics in the incident angle range of 0°-60°. Figure 9 As shown in FIG. 6, for TE polarization, the metasurface has good double-band, high-transmission, and low-frequency characteristics in the incident angle range of 0°-60°.

[0047] Preferably, the embodiment is a C-band and X-band compact low-frequency ratio metasurface, and changing the size can also be applied to other microwave bands.

[0048] In summary, compared with the prior art, the compact low-frequency ratio double-band metasurface proposed in the application has wideband, high-transmission, out-of-band steep cutoff, polarization stability, and other electromagnetic characteristics, and the overall structure is simple, light, and easy to process, and has wide application prospects in the fields of antennas, communication systems, electromagnetic countermeasures, and military stealth.

[0049] Although the content of the application has been described in detail through the above preferred embodiments, it should be recognized that the above description should not be considered as limiting the application. After reading the above content, various modifications and alternatives of the application will be apparent to those skilled in the art. Therefore, the protection scope of the application should be defined by the appended claims.

Claims

1. A compact low-frequency-ratio dual-band metasurface structure, characterized in that, The metasurface is composed of a plurality of units with the same structure arranged periodically, each unit is composed of three layers of metal patches and two layers of dielectric layers, and each adjacent two layers of metal patches are sandwiched with a layer of dielectric layer, specifically comprising: The top layer metal patch; The middle layer metal patch; The bottom layer metal patch; The first dielectric layer is sandwiched between the top layer metal patch and the middle layer metal patch; The second dielectric layer is sandwiched between the middle layer metal patch and the bottom layer metal patch; The period size of each unit is D x in the x-axis length direction D y , and D x = D y ; The top layer metal patch comprises: The top layer square ring is a square ring structure with a line width of 1 W 1. Jerusalem cross structure, no contact is arranged in the inside of the top layer square ring, and the center of the Jerusalem cross structure coincides with the center of the top layer square ring; The outer side length of the top square ring (12) L 1 less than the unit period size D x , D y ; The Jerusalem cross structure includes: a main arm forming a cross at the center, and secondary arms perpendicularly connected to the ends of the main arm, wherein the length of the main arm is... L 2 is greater than the length of the secondary arm. L 3. Width of the main boom W 2 is less than the width of the arm W 3; The structure of the bottom layer metal patch is consistent with that of the top layer metal patch; By adjusting the line width of the top layer square ring W 1, change LC The capacitance value of the parallel resonance circuit realizes the regulation and control of the C-band passband resonance frequency; by adjusting the length of the main arm of the Jerusalem cross structure L 2, change LC The inductance value of the series resonance circuit realizes the regulation and control of the X-band passband resonance frequency, so that the metasurface has a low frequency ratio characteristic of the passband.

2. The compact low-frequency-ratio dual-band metasurface structure of claim 1, wherein, The Jerusalem cross structure is equivalent to LC A series resonant circuit, the top layer square ring is equivalent to LC A parallel resonant circuit.

3. The compact low-frequency-ratio dual-band metasurface structure of claim 1, wherein, The middle layer metal patch comprises: The intermediate layer square ring is a square ring structure with a line width of 4. W 4. Square patch, no contact is arranged in the inside of the middle layer square ring, and the center of the square patch coincides with the center of the middle layer square ring.

4. The compact low-frequency-ratio dual-band metasurface structure of claim 1, wherein, The dielectric constant of the first dielectric layer and the second dielectric layer is 4.5, the loss tangent angle is 0.0035, and the thickness is 1.5mm.

5. The compact low-frequency-ratio dual-band metasurface structure of claim 3, wherein, The Jerusalem cross structure, the top layer square ring, the square patch, and the middle layer square ring all have rotational symmetry, so that the metasurface is not sensitive to the polarization of the incident electromagnetic wave, and has the polarization insensitive characteristic.

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