Near-zero-loss transmission single-ultra-wideband dual-frequency linear polarization metasurface unit and design method thereof

Abstract

The invention discloses a near-zero-loss transmission single-ultra-wideband dual-frequency linear polarization metasurface unit, which comprises a dielectric substrate, and is characterized in that the dielectric substrate is of a single-layer structure; the patch unit comprises an upper-layer metal patch and a lower-layer metal patch which are respectively pasted on the upper surface and the lower surface of the dielectric substrate, the upper-layer metal patch and the lower-layer metal patch adopt a double-ring staggered symmetrical copper structure, and specifically, the upper-layer metal patch and the lower-layer metal patch respectively comprise two semicircular metal patches which are reversely nested in a staggered manner inside and outside; the lower-layer metal patch and the upper-layer metal patch are symmetrically distributed in a mirror image dislocation manner relative to the center of the dielectric substrate, and the upper-layer metal patch and the lower-layer metal patch form a dual-frequency resonant mode; by regulating and controlling the ring width and the ring gap of the semicircular metal patches of the inner ring, dual-frequency resonance is excited in the frequency band of 30.3-42.6 GHz at the same time, and near-zero-loss transmission and near 360 degrees are achieved. And all-phase regulation and control. According to the invention, the problems of performance contradiction and multi-characteristic integration of a traditional metasurface in dual-frequency, broadband, low loss, high gain and high-purity linear polarization are solved.

Description

Technical Field

[0001] The present invention relates to the fields of communications, radar systems, and satellite communications, and in particular to a near-zero-loss transmission single-ultra-wideband dual-frequency linearly polarized metasurface unit and its design method. Aiming at the needs of 5G millimeter-wave communications, the present invention proposes a novel dual-frequency ultra-wideband linearly polarized metasurface that achieves near-zero loss and high-purity linear polarization through a unique unit design. Background Art

[0002] As an artificial two-dimensional electromagnetic material, metasurface can control the phase, polarization and amplitude of electromagnetic waves through subwavelength structure.

[0003] The existing metasurface forms are as follows: (1) Traditional metasurfaces mostly use single resonant units (such as square patches, single circular rings), which only support single frequency or narrow band (bandwidth < 10%); (2) The power transmittance is generally lower than 90%, the polarization purity is insufficient (axial ratio AR < 30dB), the multi-frequency compatibility is poor, and the energy loss is high.

[0004] Disadvantages of existing technologies: (1) Bandwidth limitation: Unable to cover 5G millimeter wave dual-band requirements (such as 28GHz / 39GHz). (2) High loss: Dielectric and metal losses lead to reduced transmittance (typical value <85%). (3) Low polarization purity: Linear polarization is susceptible to interference, affecting signal integrity. Summary of the Invention

[0005] The purpose of the present invention is to make up for the limitations of existing metasurfaces in broadband, dual-frequency and low-loss performance, and to provide a near-zero-loss transmission single ultra-wideband dual-frequency polarization metasurface unit and its design method.

[0006] The present invention is achieved through the following technical solutions:

[0007] A near-zero-loss transmission single ultra-wideband dual-frequency linear polarization metasurface unit, comprising:

[0008] A dielectric substrate having a single-layer structure;

[0009] The patch unit includes an upper metal patch and a lower metal patch respectively attached to the upper and lower surfaces of the dielectric substrate. The upper metal patch and the lower metal patch are made of double-ring staggered symmetrical copper (conductivity 5.8×10 7The invention discloses a S / m) structure, specifically: the upper metal patch and the lower metal patch each include two semi-circular metal patches that are reversely offset and nested inside and outside, the lower metal patch and the upper metal patch are distributed in a mirror-image-offset symmetric manner about the center of the dielectric substrate, and the upper metal patch and the lower metal patch form a dual-frequency resonance mode; the size and tightness of the ring are controlled by adjusting the ring width and ring gap of the inner ring semi-circular metal patch, and the dual-frequency resonance is simultaneously excited in the 30.3-42.6GHz frequency band to achieve near-zero-loss transmission.

[0010] The dielectric substrate has a side length of 5 mm and a thickness of 1.5 mm. The dielectric substrate material is F4BM220, and the relative dielectric constant ε r =2.2, loss tangent tanδ=0.0014.

[0011] The radius of the semicircular metal patch of the inner ring is 0.4 mm, the ring width is 0.5 mm, and the ring gap is 0.3 mm.

[0012] The dual-frequency resonance mode includes:

[0013] The first resonant frequency is 31.33 GHz, corresponding to a free-space wavelength of 9.58 mm;

[0014] The second resonant frequency is 41.01 GHz, corresponding to a free-space wavelength of 7.31 mm;

[0015] The relative bandwidth of the two resonant frequencies is 33.74%, and the reflectivity in both frequency bands is less than 0.01%.

[0016] The surface current distribution of the upper metal patch and the lower metal patch is orthogonal and symmetrical:

[0017] Low-frequency resonance: Current flows along the outer metal patch, forming a larger ring current path. The size of the outer metal patch dominates the low-frequency resonance. The standing wave mode of the current achieves maximum coupling at this frequency, and energy is efficiently transmitted through the electromagnetic resonance of the outer metal patch.

[0018] High-frequency resonance: The current is concentrated in the inner ring metal patch and the dislocation area, and the path is short. The size of the inner ring metal patch excites high-frequency resonance through strong local coupling, and the rapid oscillation of the current forms a high-frequency electromagnetic response.

[0019] The dual-ring staggered symmetrical copper structure ensures independent dual-frequency regulation.

[0020] A design method for a near-zero-loss transmission single ultra-wideband dual-frequency linearly polarized metasurface unit specifically comprises the following steps:

[0021] The width and gap of the semicircular metal patch of the inner ring are used as control parameters;

[0022] By using the parameter optimization module of Ansys HFSS electromagnetic simulation software, the dual-ring staggered symmetrical copper structure was able to simultaneously achieve single-band dual-frequency resonant matching and ultra-wideband near-zero-loss transmission within the target frequency band.

[0023] Verify the power transmittance, axial ratio and gain indicators, and screen the unit structure parameters that meet the transmittance>87.6%, axial ratio>85.4dB, and gain>20dBi.

[0024] A near-zero-loss transmission single-ultra-wideband dual-frequency linear polarization metasurface unit array comprises the metasurface units described above, which are arranged in a square array with a period of P=5 mm, with 400 repeated metasurface units.

[0025] The array aperture is 10cm×10cm, and the peak gains at 31.33GHz and 41.01GHz reach 22.91dBi and 26.41dBi respectively, and the 3dB gain bandwidth covers 32.8-42.2GHz; the axial ratios at 31.33GHz and 41.01GHz reach 97.99dB and 92.84dB respectively.

[0026] The role of dielectric substrate: The metasurface unit uses F4BM220 as the dielectric substrate material, and its relative dielectric constant is ε r =2.2, and the loss tangent is tanδ = 0.0014. This material has the characteristics of low dielectric constant and low loss tangent, which can effectively reduce the energy loss of electromagnetic waves during transmission in high frequency bands (such as 30.3-42.6GHz), ensuring high-quality signal transmission.

[0027] Resonance mechanism of the dual-ring staggered symmetrical copper structure: The patch unit adopts a dual-ring staggered symmetrical copper structure. The upper and lower metal patches are respectively composed of internally and externally staggered nested circular rings, and the lower metal patch and the upper metal patch are distributed in a mirror-image staggered symmetric manner about the center of the dielectric substrate. This structure can simultaneously excite dual-frequency resonance in the 30.3-42.6GHz frequency band by regulating the ring width and ring gap. Specifically, when an electromagnetic wave is incident on this structure, due to the geometric shape and size parameters of the circular ring, resonance will occur at specific frequencies, so that the energy of the electromagnetic wave is effectively transmitted and enhanced at these frequency points, thereby realizing a dual-frequency resonance mode.

[0028] Transmission and polarization characteristics of electromagnetic waves: This metasurface unit achieves high-purity linear polarization, which selectively enhances and suppresses the electric field component of the electromagnetic wave in a specific direction. The dual-ring staggered structure can control the incident electromagnetic wave, maintaining a high linear polarization purity during transmission, with an axial ratio exceeding 85.4dB. This means that within this frequency band, the electric field vector of the electromagnetic wave vibrates primarily in one direction, while vibration components in other directions are effectively suppressed, thereby improving the transmission quality and directionality of the electromagnetic wave.

[0029] Ultra-wideband: The metasurface unit is capable of dual-frequency resonance within the ultra-wideband frequency band of 30.3-42.6 GHz, covering a wide frequency range. This ultra-wideband feature enables it to adapt to the needs of various communication and radar systems and meet the requirements of high-frequency signal transmission.

[0030] High Gain: By optimizing the dual-ring staggered structure, the unit can achieve a gain of over 20dBi. High gain means a stronger output signal at the same input power, thereby improving the transmission distance and coverage of the communication system.

[0031] Near-zero-loss transmission: Within the 30.3-42.6 GHz frequency band, power transmittance exceeds 87.6%, achieving extremely low loss and enabling nearly 360° full phase control. This is primarily due to the low-loss characteristics of the F4BM220 material and the effective electromagnetic wave control provided by the dual-ring staggered structure. Low-loss transmission significantly improves system efficiency and reduces energy waste, making it particularly suitable for applications requiring high signal quality.

[0032] High-purity linear polarization: The high-purity linear polarization with an axial ratio exceeding 85.4dB gives the metasurface unit greater directionality and selectivity in the transmission and reception of electromagnetic waves. This helps reduce signal interference and crosstalk, improving the anti-interference capability and signal quality of the communication system.

[0033] Simple and Compact Structure: The metasurface unit utilizes a single-layer dielectric substrate and a double-ring, staggered, symmetrical patch structure. The overall structure is simple and compact, making it easy to process and integrate. This structural design not only reduces manufacturing costs but also facilitates integration with other systems, showing promising engineering application prospects.

[0034] The advantages of the present invention are: the present invention solves the performance contradictions of traditional metasurfaces in dual-frequency, broadband, low loss, high gain and high polarization purity. The present invention is dual-frequency compatible: it simultaneously supports dual frequency bands of 31.33GHz and 41.01GHz. The ultra-wideband of the present invention covers 30.3-42.6GHz (the relative bandwidth is 33.74%), the present invention has near-zero loss, a transmittance of >87.6%, and is 98.3% and 98.7% at the dual resonant frequency points respectively. The present invention has high polarization purity: the intra-band axial ratio AR is >85.4dB. The present invention has high gain, and the intra-band gain is >20dBi. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a structural schematic diagram of the present invention;

[0036] Figure 2 A top view of the present invention;

[0037] Figure 3 This is an array diagram of the present invention;

[0038] Figure 4 This is the near-zero loss transmission analysis diagram of the present invention ( Figure 4 (a) For fixed m = 0.3 mm, different variables n, corresponding S 11 ; Figure 4 (b) For fixed n = 0.5 mm, different variables n, corresponding S 11 ; Figure 4 (c) For fixed m = 0.3 mm, different variables n, corresponding S 21 ; Figure 4 (d) for fixed n = 0.5 mm, different variable n, corresponding);

[0039] Figure 5 is a simulation result diagram of the present invention. (Figure 5 (a) and (b) are S 11 and reflection efficiency; Figure 5(c)(d)(e) are S 21 , transmission efficiency and S 21 Phase; Figure 5 (f) (g) are AR (axis ratio) and Gain (gain) respectively;

[0040] FIG6 is a diagram of the simulation results of the present invention under oblique incidence. (FIG. 6(a) is a diagram of the simulation results of the present invention under oblique incidence.) 11 (reflection coefficient); Figure 6(b) is S under oblique incidence 21 (transmission coefficient); Figure 6(c) is the AR (axial ratio) under oblique incidence; Figure 6(d) is the Gain (gain) under oblique incidence) DETAILED DESCRIPTION

[0041] like Figure 1 、 2 As shown, a near-zero-loss transmission single ultra-wideband dual-frequency polarization metasurface unit includes:

[0042] A dielectric substrate 1 having a single-layer structure;

[0043] The patch unit includes an upper metal patch 2 and a lower metal patch 3 respectively attached to the upper and lower surfaces of the dielectric substrate 1. The upper metal patch 2 and the lower metal patch 3 are made of double-ring staggered symmetrical copper (conductivity 5.8×10 7 The S / m) structure is as follows: the upper metal patch 2 and the lower metal patch 3 each include two semi-circular ring metal patches that are reversely offset and nested inside and outside. The lower metal patch 3 and the upper metal patch 2 are distributed in a mirror-image-offset symmetric manner with respect to the center of the dielectric substrate 1. The overall shape, viewed from the positive Z semi-axis to the negative Z semi-axis, is two circular rings, like four staggered crescents of different sizes. The upper metal patch 2 and the lower metal patch 3 form a dual-frequency resonance mode; by adjusting the matching relationship between the ring width and the ring gap of the inner ring semi-circular ring metal patch, dual-frequency resonance is simultaneously excited in the 30.3-42.6GHz frequency band to achieve near-zero loss transmission. The dual-ring staggered symmetrical metal structure achieves the purpose of ultra-wideband and low-loss transmission by optimizing the variable relationship between the ring width and the ring gap.

[0044] The dielectric substrate has a side length of 5 mm and a thickness of 1.5 mm. The dielectric substrate material is F4BM220 and has a relative dielectric constant of ε r =2.2, loss tangent tanδ= is 0.0014.

[0045] The radius of the semicircular metal patch of the inner ring is 0.4 mm, the ring width is 0.5 mm, and the ring gap is 0.3 mm.

[0046] The dual-frequency resonance mode (dual Huygens resonance state) includes:

[0047] The first resonant frequency is 31.33 GHz, corresponding to a free-space wavelength of 9.58 mm;

[0048] The second resonant frequency is 41.01 GHz, corresponding to a free-space wavelength of 7.31 mm;

[0049] The relative bandwidth of the two resonant frequencies is 33.74%, and the reflectivity in both frequency bands is less than 0.01%.

[0050] The current distribution and dual-frequency resonance mechanism, the surface current distribution of the upper metal patch and the lower metal patch is orthogonal and symmetrical:

[0051] Low-frequency resonance (31.33 GHz): Current flows along the outer metal patch, forming a larger ring current path (corresponding to the low-frequency wavelength). The size of the outer metal patch (determined by the gap m and the ring width n) dominates the low-frequency resonance. The standing wave mode of the current achieves maximum coupling at this frequency, and energy is efficiently transmitted through the electromagnetic resonance of the outer metal patch.

[0052] High-frequency resonance (41.01 GHz): The current is concentrated in the inner ring metal patch and the dislocation area, with a short path (corresponding to the high-frequency wavelength). The size of the inner ring metal patch (radius r and ring width n) excites high-frequency resonance through strong local coupling, and the rapid oscillation of the current forms a high-frequency electromagnetic response.

[0053] The staggered design breaks the symmetry, avoids mode degeneracy, and ensures independent control of the dual frequencies.

[0054] like Figure 4 As shown, Figure 4 (a) The variable n is 0.3mm, 0.4mm, 0.5mm, 0.6mm, and 0.7mm. The resonant frequency corresponding to different n values, S 11 and effective bandwidth (in S 11 <-10dB below). It can be clearly observed that n = 0.5mm, 0.6mm, and 0.7mm can achieve dual resonance within one frequency band. Among these three variables, the smaller n, the larger the bandwidth. While n = 0.4mm and 0.3mm have larger bandwidths, they achieve resonance within two frequency bands. This shows that n (ring width) affects the resonance characteristics and matching performance of the device. Figure 4 (b) The variable m is set to 0.1mm, 0.2mm, 0.3mm, 0.4mm, and 0.5mm. The change of m also significantly affects S 11 It can be clearly observed that from 28 GHz to 36 GHz, as m increases, the resonant frequency moves closer to the lower frequency side, while S 11 The smaller the value, the smaller the value. From 36GHz to 45GHz, there is no significant difference between the variables, which indicates that the adjustment of m (ring gap) will change the electromagnetic coupling characteristics of the structure, thereby affecting the impedance matching effect. Both figures focus on the relationship between structural parameters (m, n) and RF performance. By comparing S under different parameters, 11 The curve can be used to analyze the influence of size on device matching performance, provide data support for optimizing the design of metasurface unit structure, and ensure better impedance matching in the target frequency band (28–45 GHz). 4(c) The variable n is 0.3mm, 0.4mm, 0.5mm, 0.6mm, and 0.7mm. The S corresponding to different n values ​​is 21For example, changes in n will lead to significant changes in transmission loss at a specific frequency. For example, when n = 0.4mm, the loss is large near 30GHz, and when n = 0.7mm, the loss changes significantly in the high frequency band, reflecting the regulatory effect of n on the transmission characteristics of the device. The closer the curve is to 0dB, the higher the signal transmission efficiency in this frequency band. By optimizing n, the transmission efficiency of the target frequency band can be adjusted; 4(d) The variable m takes 0.1mm, 0.2mm, 0.3mm, 0.4mm, and 0.5mm. Changes in m also affect S 21 Curve. For m = 0.2mm, a deep valley appears near 29GHz, indicating high loss. However, above 33GHz, the loss is relatively small, with no significant difference between the variables. This indicates that m is a key parameter for regulating transmission loss, and adjusting m can optimize the device's signal transmission performance in different frequency bands. Analysis of Figures (a), (b), (c), and (d) reveals that considering n = 0.5mm and m = 0.3mm, single ultra-wideband dual-band and near-zero loss transmission can be achieved simultaneously.

[0055] A design method for a near-zero-loss transmission single ultra-wideband dual-frequency linearly polarized metasurface unit specifically comprises the following steps:

[0056] The width and gap of the semicircular metal patch of the inner ring are used as control parameters;

[0057] By optimizing the parameter combination through electromagnetic simulation, the dual-ring staggered symmetrical copper structure can simultaneously meet single-band dual-frequency resonant matching and ultra-wideband near-zero loss transmission within the target frequency band.

[0058] Verify the power transmittance, axial ratio and gain indicators, and screen the unit structure parameters that meet the transmittance>87.6%, axial ratio>84.5dB, and gain>20dBi.

[0059] like Figure 3 As shown, a near-zero-loss transmission single-ultra-wideband dual-frequency linear polarization metasurface unit array includes the metasurface units, which are arranged in a square array with a period of P=5mm, and 400 metasurface units are repeated.

[0060] The array aperture is 10cm×10cm, and the peak gains at 31.33GHz and 41.01GHz reach 22.91dBi and 26.41dBi respectively, and the 3dB gain bandwidth covers 32.8-42.2GHz; the axial ratios at 31.33GHz and 41.01GHz reach 97.99dB and 92.84dB respectively.

[0061] The data design of the present invention is shown in Table 1

[0062] Table 1

[0063] r n m L H p 0.4mm 0.5mm 0.3mm 5mm 1.5mm 5mm

[0064] The radius of the small ring is r, the ring width is n, the ring gap is m, the side length of the dielectric plate is L, and the thickness is H. The unit model is as follows Figure 1 、 2 As shown, the relative dielectric constant ε of the copper clad laminate r =2.2, loss tangent tanδ = 0.0014, side length is L×L, thickness is H. The surface conductivity of the copper sheet is 5.8×10 7 S / m. Its shape, viewed from the positive z-axis toward the negative z-axis, is two circular rings. Overall, it resembles four staggered crescents. The inner radius of the smaller ring is r, the ring width is n, the ring spacing is m, and the array period is p.

[0065] The ultra-wideband design of this invention surpasses existing technologies in power transmittance, power reflectance, polarization purity, and gain. At 31.33 GHz, the power transmittance is 98.3%, the power reflectance is 0.0065%, the axial ratio is 97.99 dB, and the gain is 22.91 dBi. At 41.01 GHz, the power transmittance is 98.7%, the power reflectance is 0.0032%, the axial ratio is 92.84 dB, and the gain is 26.41 dBi. Process compatibility (mass production): The device can be manufactured using standard PCB processes, making it suitable for large-scale production.

[0066] Effect verification:

[0067] The Ansys HFSS high-frequency structural simulation solver and high-performance computing platform were used. An air box was created with the upper and lower surfaces each half the wavelength away from the dielectric plate, with a side length of L, coinciding with the edge of the dielectric plate. Floquet port 1 excitation was then set on the upper surface of the air box, and Floquet port 2 excitation on the lower surface. Master and slave boundary conditions were set on all four sides. This method simplifies modeling and calculation by combining units. For large arrays or periodically distributed structures, there is no need to model the entire structure; only one unit can be extracted for modeling. By setting periodic boundary conditions, the electromagnetic characteristics of infinitely large periodic structures can be simulated, significantly reducing the amount of calculation and modeling complexity.

[0068] As shown in the simulation diagrams of Figure 5(a)-(g), simulation data: HFSS simulation shows that in the frequency band from 30.3GHz to 42.6GHz, S 21 >-0.57dB, transmittance>87.6%. At 31.33GHz, S 21 =-0.075dB, power transmittance is 98.3%, S 11 =-41.85dB, power reflectivity is 0.0065%, axial ratio is 97.99dB, gain is 22.91dBi; at 41.01GHz, S 21 =-0.058dB, power transmittance is 98.7%, S11 =-44.96dB, the power reflectivity is 0.0032%, the axial ratio is 92.84dB, and the gain is 26.41dBi.

[0069] S 11 The power reflectivity conversion formula and S 21 The conversion formula with power transmittance is as follows:

[0070] Reflection efficiency=|Γ| 2 , |Γ|≤1; Γ(reflection coefficient)=|S 11 |=S 11 Amplitude (dB)

[0071] Similarly Transmissi on efficiency=|T| 2 , |T|≤1; T (transmission coefficient)

[0072] At 31.33GHz, S 11 =-41.85dB; at 41.01GHz, S 11 =-44.96dB, at this time Reflection efficiency=|Γ1| 2 =0.00006561 Reflection efficiency = |Γ2| 2 =0.00003136

[0073] At 31.33GHz, S 21 =-0.07572dB; at 41.01GHz, S 21 =-0.05825dB, at this time Transmissi on efficiency=|T1| 2 =0.9829 Transmissi on efficiency=|T1| 2 =0.9867.

[0074] As shown in the simulation diagram of Figure 6 (a) (b), simulation data: HFSS simulation shows that when the oblique incident angle is 5° and 0° (vertical incidence), it can be clearly seen that the reflection coefficient S 11 and transmission coefficient S 21, whether in the lower frequency band 28-36.5GHz or in the higher frequency band 36.5-45GHz, there is almost no difference. When the oblique incident angle is 15°, there is no big change in the low frequency band. In the high frequency band, the high frequency resonant frequency shifts to the low frequency by 0.89GHz. At 41-42.5GHz, the reflection coefficient S 11 It rose to -5dB, and the transmission coefficient dropped to -2.56dB. In addition, a new resonant frequency of 43.2GHz was added. When the oblique incident angle was 30°, there was still no change in the low frequency band. From 34.4-45GHz, compared with the vertical incidence, the change was obvious. Not only was a new resonant frequency of 43.21GHz added, but the high-frequency resonant frequency also shifted significantly to the low frequency, and the transmission loss increased.

[0075] As shown in the simulation diagrams of Figure 6(c)(d), simulation data: HFSS simulation shows that when the oblique incident angle is 5°, the AR (axial ratio) waveform is similar to that at vertical incidence. In the range of 30.3-42.6, the AR decreases slightly, but always maintains AR>85.4dB; the Gain is almost the same as that at vertical incidence. When the oblique incident angle is 15°, the fluctuation is not obvious in the low-frequency band. At the resonant frequency of 31.33 GHz, the AR drops by about 16 dB, but it fluctuates greatly in the high-frequency band. At 41.2 GHz, the AR exceeds 120 dB. The gain does not change much from the low-frequency band to the waveform. In the high-frequency band, the gain drops by a maximum of 3.68 dBi at 41.89 GHz. When the oblique incident angle is 30°, the AR changes significantly across the entire frequency band, and the waveform jitter is very serious. The gain does not change particularly significantly in the low-frequency band. At 31.33 GHz, the gain drops by only about 1 dBi. At the high-frequency resonant frequency of 41.01 GHz, it is 24.1 dBi, which is greater than 41.01 GHz, and the gain drop is more obvious.

[0076] In summary, by analyzing the S parameters, axial ratio, and gain at different oblique incident angles (0°, 5°, 15°, and 30°), we can draw the following conclusions: As the oblique incident angle increases, the metasurface performs relatively well at the resonant frequency of 31.33 GHz. At high frequencies, due to the local influence of the structural dimensions of the inner ring unit of the metasurface, the performance deteriorates compared to normal incidence as the oblique incident angle increases. Therefore, it can be guaranteed that the metasurface can still maintain relatively good S parameter, AR, and Gain performance parameters at oblique incidence from 0° to 15°.

Claims

1. A near-lossless transmission single ultra-wideband dual-frequency linear polarization metasurface unit, characterized by: Includes: A dielectric substrate having a single-layer structure; The patch unit includes an upper metal patch and a lower metal patch respectively attached to the upper and lower surfaces of a dielectric substrate. The upper metal patch and the lower metal patch adopt a double-ring staggered symmetrical copper structure. Specifically, the upper metal patch and the lower metal patch each include two semi-circular metal patches that are nested and staggered in opposite directions. The lower metal patch and the upper metal patch are distributed in a mirror-image staggered symmetrical manner about the center of the dielectric substrate. The upper metal patch and the lower metal patch form a dual-frequency resonance mode.

2. The near-zero-loss transmission single-ultra-wideband dual-frequency linear polarization metasurface unit according to claim 1, characterized in that: By adjusting the ring width and the ring gap of the semicircular metal patch of the inner ring, the size and tightness of the ring are controlled, and dual-frequency resonance is simultaneously excited in the 30.3-42.6GHz frequency band to achieve near-zero loss transmission.

3. The near-zero-loss transmission single-ultra-wideband dual-frequency linear polarization metasurface unit according to claim 1, characterized in that: The dielectric substrate has a side length of 5 mm and a thickness of 1.5 mm. The dielectric substrate is made of F4BM220, has a relative dielectric constant of 2.2, and a loss tangent of 0.0014.

4. The near-zero-loss transmission single-ultra-wideband dual-frequency linear polarization metasurface unit according to claim 1, characterized in that: The radius of the semicircular metal patch of the inner ring is 0.4 mm, the ring width is 0.5 mm, and the ring gap is 0.3 mm.

5. The near-zero-loss transmission single-ultra-wideband dual-frequency linear polarization metasurface unit according to claim 1, characterized in that: The dual-frequency resonance mode includes: The first resonant frequency is 31.33 GHz, corresponding to a free-space wavelength of 9.58 mm; The second resonant frequency is 41.01 GHz, corresponding to a free-space wavelength of 7.31 mm; The relative bandwidth of the two resonant frequencies is 33.74%, and the reflectivity in both frequency bands is less than 0.01%.

6. The near-zero-loss transmission single-ultra-wideband dual-frequency linear polarization metasurface unit according to claim 5, characterized in that: The surface current distribution of the upper metal patch and the lower metal patch is orthogonal and symmetrical: Low-frequency resonance: Current flows along the outer metal patch, forming a larger ring current path. The size of the outer metal patch dominates the low-frequency resonance. The standing wave mode of the current achieves maximum coupling at this frequency, and energy is efficiently transmitted through the electromagnetic resonance of the outer metal patch. High-frequency resonance: The current is concentrated in the inner ring metal patch and the dislocation area, and the path is short. The size of the inner ring metal patch excites high-frequency resonance through strong local coupling, and the rapid oscillation of the current forms a high-frequency electromagnetic response. The dual-ring staggered symmetrical copper structure ensures independent dual-frequency regulation.

7. A design method for a near-zero-loss transmission single-ultra-wideband dual-frequency linearly polarized metasurface unit, characterized by: The specific steps include: The width and gap of the semicircular metal patch of the inner ring are used as control parameters; By using the parameter optimization module of Ansys HFSS electromagnetic simulation software, the dual-ring staggered symmetrical copper structure was able to simultaneously achieve single-band dual-frequency resonant matching and ultra-wideband near-zero-loss transmission within the target frequency band. Verify the power transmittance, axial ratio and gain indicators, and screen the unit structure parameters that meet the power transmittance>87.6%, axial ratio>85.4dB, and gain>20dBi.

8. A near-zero-loss transmission single ultra-wideband dual-frequency linearly polarized metasurface unit array, characterized by: The method comprises the metasurface unit according to any one of claims 1 to 6, which is arranged in a square array with a period of P=5 mm, and 400 metasurface units are repeated.

9. The near-zero-loss transmission single ultra-wideband dual-frequency linear polarization metasurface unit array according to claim 8, characterized in that: The array aperture is 10cm×10cm, and the peak gains at 31.33GHz and 41.01GHz reach 22.91dBi and 26.41dBi respectively, and the 3dB gain bandwidth covers 32.8-42.2GHz; the axial ratios at 31.33GHz and 41.01GHz reach 97.99dB and 92.84dB respectively.

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