All-dielectric reflectarray antenna

Abstract

An antenna comprises a support layer and a reflecting element arranged on the support layer for reflecting an incident wave with a corresponding reflection phase, the reflecting element extending vertically from the support layer with a height configured to achieve the respective reflection phase, the support layer and the reflecting element being formed of an all-dielectric material. The antenna is less susceptible to metal corrosion and is flexible in design. It provides complete reflection and phase adjustment simultaneously with a simple and compact structure. The simple structure of the antenna enables it to be manufactured in an efficient and economical manner.

Description

Technical Field

[0001] This invention relates to an antenna. More specifically, this invention relates to an antenna based on an all-dielectric metamaterial. Background Technology

[0002] Over the past century, with the rapid development of the communications industry, antenna research has become a crucial area of ​​focus. There are many types of antennas, primarily including patch antennas, slot antennas, dielectric resonator antennas (DRAs), and various antenna arrays. Almost all of these antennas contain metallic materials, whether used to form radiators or grounding elements. Metallic materials are prone to corrosion in outdoor environments, which can damage the mechanical and electrical properties of the antenna and even affect the quality of wireless communication.

[0003] To address these issues, two main methods have been employed: coatings and radomes. Both metallic and inorganic coatings effectively isolate metals from the external environment, thus slowing down corrosion. However, these solutions may be ineffective in harsh environments, such as areas near the equator exposed to high temperatures and strong ultraviolet radiation, which accelerates metal corrosion. In the Arctic Circle, extremely low temperatures cause inorganic coatings to fail. Similarly, in desert environments with large diurnal temperature variations, thermal expansion and contraction accelerate coating corrosion and deformation. This also occurs on islands and ships with high temperatures, high humidity, and high salt spray. While radar radomes can replace coatings, they are also unsuitable for harsh environments. In short, while both methods can slow down metal corrosion, they cannot completely prevent it. Furthermore, implementing these solutions increases the cost and complexity of the antenna system. On the other hand, all-dielectric antennas are completely immune to metal corrosion. Therefore, without increasing cost and complexity, all-dielectric antennas are more suitable for outdoor environments, especially harsh ones.

[0004] In recent years, reflectarray antennas have also been studied. However, many reflectarray antennas require a metallic ground plane to achieve optimal reflection. Additionally, some studies have suggested using all-dielectric metamaterials (ADMs) instead of metallic ground planes. However, the initial design of ADM-based antennas typically requires four or more layers to achieve reflection for each frequency band, resulting in an increase in antenna height. Summary of the Invention

[0005] In a first aspect, the present invention provides an antenna including a support layer and a reflective element disposed on the support layer, the reflective element being configured to reflect an incident wave with a corresponding reflection phase. The reflective element extends perpendicularly to the support layer to a height configured to achieve its respective reflection phase, and both the support layer and the reflective element are formed of an all-dielectric material.

[0006] In some embodiments, the support layer has a first dielectric constant and the reflective element has a second dielectric constant, wherein the second dielectric constant is higher than the first dielectric constant.

[0007] In some embodiments, the reflective unit is a single-layer structure.

[0008] In some embodiments, the reflective unit further includes a central portion and two arm portions connected to either side of the central portion, wherein the two arm portions form an angle of 180° with each other.

[0009] In some embodiments, the central portion has a first height, while each arm portion has a second height, wherein the second height is less than half of the first height.

[0010] In some embodiments, the first height is between 3 mm and 7 mm.

[0011] In some embodiments, the second height is 2.5 mm.

[0012] In some embodiments, the central portion is aligned with the support layer on the same central axis.

[0013] In some embodiments, each arm portion extends from the central portion along the direction of the electric field.

[0014] In some embodiments, the central portion is cylindrical.

[0015] In some embodiments, the width of each arm portion is smaller than the diameter of the central portion.

[0016] In some embodiments, the radius of the central portion is 2.15 mm.

[0017] In some embodiments, the support layer is hexagonal.

[0018] In some embodiments, each arm portion is aligned with the edge of the support layer.

[0019] In some embodiments, the width of each arm portion is approximately one-third the width of the edge of the support layer.

[0020] In some embodiments, the width of each arm portion is 1 mm.

[0021] In some embodiments, the diagonal length of the support layer is 10 mm.

[0022] In some embodiments, the antenna described above is symmetrical about a center of rotation.

[0023] In some embodiments, the antenna is configured to operate within a reflection bandwidth defined by the interval between the magnetic resonant frequency and the electromagnetic resonant frequency.

[0024] In some embodiments, the reflection bandwidth is determined by the width of the reflection element.

[0025] In some embodiments, the reflection bandwidth is determined by the height of the reflection unit.

[0026] In some embodiments, the antenna is formed using 3D printing technology.

[0027] In some embodiments, the antenna is configured to operate in the Ka band or THz band.

[0028] In some embodiments, the antenna includes a plurality of reflective elements arranged in an array on a support layer, wherein the plurality of reflective elements are configured to collectively form a predetermined phase distribution pattern to reflect incident waves to a predetermined direction.

[0029] Exemplary embodiments of the present invention thus provide an antenna that is resistant to metal corrosion and offers flexible design freedom due to the arbitrary selection of its materials and shape, provided that it enables the interaction between electromagnetic waves and dielectric particles to achieve Mie resonance. Furthermore, a simple and compact antenna structure can be achieved with only one reflective element, which is highly efficient and cost-effective in manufacturing, while providing complete reflection and phase adjustment. Attached Figure Description

[0030] To gain a more accurate understanding of the invention described above, a more detailed description will be provided with reference to specific embodiments shown in the accompanying drawings. The drawings herein may not be drawn to scale, and the dimensions mentioned in the drawings or the following description apply only to the disclosed embodiments.

[0031] Figure 1a A Mie resonance simulation model of the antenna's reflecting element according to an embodiment of the present invention is shown.

[0032] Figure 1b It shows Figure 1a The diagram shows the resonance point and its field distribution in the Mie resonance simulation.

[0033] Figure 2a A schematic diagram of an antenna according to an embodiment of the present invention is shown.

[0034] Figure 2b for Figure 2a A schematic side view of the antenna.

[0035] Figure 2c for Figure 2a A schematic top view of the antenna.

[0036] Figure 3 A graph comparing the reflection bandwidth of two antennas according to an embodiment of the present invention.

[0037] Figure 4 The diagram illustrates the relationship between the height of the reflective element of an antenna according to an embodiment of the present invention and its reflection phase and coefficient.

[0038] Figure 5 The relationship between the normalized reflection phase of an antenna's reflecting element and its height, according to an embodiment of the present invention, is illustrated.

[0039] Figure 6 This is a schematic diagram of an antenna transmitting incident waves according to an embodiment of the present invention.

[0040] Figure 7 This is a schematic diagram illustrating the gain release of a reflective array antenna under different phase distributions according to an embodiment of the present invention.

[0041] Figure 8a A top view of an experimental setup having a prototype antenna and a fed horn antenna according to an embodiment of the present invention is shown.

[0042] Figure 8b A side view of an experimental setup having a prototype antenna and a fed horn antenna according to an embodiment of the present invention is shown.

[0043] Figure 9a An optical image of an antenna according to an embodiment of the present invention is shown.

[0044] Figure 9b Showing Figure 9a A close-up view of the antenna, showing the reflector element in detail.

[0045] Figure 10 A graph showing the co-polarized and cross-polarized radiation patterns at 29 GHz in the upward-looking plane.

[0046] Figure 11 A graph showing the co-polarized and cross-polarized radiation patterns at 29 GHz in the azimuth plane.

[0047] Figure 12 The actual gain diagram of the antenna measurement and simulation according to an embodiment of the present invention is shown. Detailed Implementation

[0048] Most high-gain antennas on the market use metallic materials, which are susceptible to corrosion in outdoor environments. Corrosion can impair the mechanical and electrical performance of the antenna and may even affect the quality of wireless communication. Antennas made of metallic metamaterials typically rely on LC resonant circuits. However, traditional metallic metamaterials lack flexibility in unit shape, which may limit their applications.

[0049] Existing all-dielectric reflective antennas typically require multiple dielectric layers to achieve total reflection and multiple dielectric particles to adjust the phase. Therefore, the structure of such antennas is quite complex.

[0050] In order to at least address some of the shortcomings of the prior art, the inventors of this invention have developed an antenna that contains no metal materials while maintaining a simple and compact antenna structure, so as to achieve efficient and cost-effective manufacturing.

[0051] More specifically, this invention provides a reflective array antenna based on all-dielectric metamaterials (ADM) to simultaneously achieve total reflection and phase adjustment. The antenna of this invention comprises only one reflective element and can operate in the Ka-band. This antenna can be used as a high-gain antenna for satellite communications, radar, remote sensing, and 5G antennas. It is particularly suitable for outdoor and harsh environments.

[0052] In recent years, the application of all-dielectric metamaterials (ADMs) as antenna materials has been extensively studied. Unlike traditional metallic metamaterials that rely on the shape of each unit cell, ADMs are based on the Mie resonance principle. These resonances are generated through the interaction between electromagnetic waves and dielectric particles, resulting in electrical or magnetic resonances. The separation between electrical and magnetic resonances provides a broad reflection window for the effective operation of the antenna.

[0053] To demonstrate Mie resonance, a computational simulation was performed using ANSYS HFSS. Figure 1a As shown in the simulation model, HFSS designed a cylindrical element 101, which represents the first embodiment of the antenna reflection element 101 according to the present invention. The required reflection amplitude and phase response of the reflection element 101 can be obtained by utilizing the Floquet model with infinite periodic boundary conditions.

[0054] In the simulation, the dielectric constant of the reflective unit 101 was set to 12, and the side length p of the square period was 8 mm. The radius a and height h of the cylinder were set to 2.15 mm and 1.9 mm, respectively.

[0055] Given that Figure 1b The reflection coefficient of the shown reflection unit 101 has two resonance points: the first resonance point 110 is an electric field resonance point, and the second resonance point 12 is a magnetic field resonance point. It can be determined that the first resonance point is the TE01 mode, i.e., the first Mie resonance; the second resonance point is the TM01 mode, i.e., the second Mie resonance. When optimizing a cylindrical unit 100 with a radius of 1.9 mm and a height of 2.3 mm, the first and second Mie resonance points will separate, as shown... Figure 3 As shown. This achieves a -1dB reflection window from 27.9GHz to 30.2GHz, which translates to a 7.9% reflection bandwidth.

[0056] To achieve a wider reflection bandwidth and higher efficiency, a second embodiment of the reflection unit 101 is provided, in which two arms are added to the central cylindrical portion along the electric field direction, with the width and height of each arm set to 1 mm and 2.5 mm, respectively.

[0057] Specifically, Figure 2a A schematic diagram of an antenna 100 according to a second embodiment of the present invention is shown. The antenna 100 includes a support layer 109, on which a reflecting element 101 is disposed. The reflecting element 101 also includes a central portion 150, which is cylindrical in this embodiment, and two arm portions 107 connected to the central portion 105 on opposite sides of the central portion 105. The two arm portions 107 extend from the central portion 105 along the electric field direction and form an angle of 180° with each other. Each arm portion 107 has a cuboid or rectangular prism shape, wherein the end of each arm portion 107 is aligned with the center line corresponding to the edge of the support layer 109.

[0058] In this embodiment, the support layer 109 is hexagonal. Alternatively, it can have other shapes depending on the antenna design. The central portion 105 is located at the center of the support layer 109, and both the central portion 105 and the support layer 109 are located on the same central axis. Each arm portion 107 contacts the edge of the hexagonal support layer 109, such that the reflector element 101 and the antenna 100 are symmetrical about the center of rotation.

[0059] Both the reflector element 101 and the support layer 109 of the antenna 100 are made of ADM. As long as the dielectric constant ε of the reflector element 101 is... r2 Dielectric coefficient ε greater than 109 of the support layer r1 Therefore, the selection of component materials for antenna 100 has design freedom. In one embodiment, the dielectric constant ε of the support layer 109 is... r1 The dielectric constant ε of the reflecting unit is 3. r2 It is 12.

[0060] Now for reference Figure 2b The figure shows a side view of antenna 100. Reflecting element 101 extends vertically from support layer 109 at a height of h. Specifically, the central portion 105 has a height of h and a radius of a, while the arm portion has a height of h. a The height h of the arm section is 107. a It is less than half the height h of the central portion 105, but greater than the thickness t of the support layer 109. In this embodiment, the thickness t of the support layer 109 is 0.6 mm.

[0061] like Figure 2c As shown, the width w of the arm portion 107 aSlightly smaller than the diameter 2a of the center. Furthermore, the width w a The diameter 2a of the central portion 105 is approximately one-third the length of the edge of the hexagonal support layer 109, and the arm portion 107 contacts this edge. The diameter 2a of the central portion 105 is slightly less than one-third the length p of the diagonal of the support layer 109.

[0062] In one specific embodiment, the diagonal length p of the hexagonal support layer 109 is 10 mm. The height h of the arm... a The width 'a' is 2.5 mm and the radius 'a' is 1 mm.

[0063] By optimizing the radius a and height h of the central portion 105, the antenna's reflection bandwidth 100 can be extended to 15% (27.5–32 GHz). Figure 3 A comparison of the reflection bandwidth between a reflective unit having a first structure 310 and a reflective unit having a second structure 320 is shown. The reflective unit with the first structure 310 includes a central portion and two arm portions connected to both sides of the central portion, while the second structure 320 includes only a cylinder. Figure 3 As shown, the reflection bandwidth of the reflection unit with the first structure 310 is wider than that of the reflection unit with the second structure 320.

[0064] By changing the height h of the reflective unit 101 from 3mm to 7mm, as Figure 4 As shown, the overlapping -1dB reflection bandwidth is 15.4% (25.9–30.2 GHz). If identical reflecting elements are used to construct the reflection array, the incident wave will reach each element at different distances due to their different positions, resulting in different reflection phases. Therefore, phase compensation is needed to eliminate the differences in element positions, after which the reflection phase will be normalized to the same direction, thus achieving good reflection performance.

[0065] Still referencing Figure 4 It can be clearly seen that for each reflective element height (h), the reflection phase of the reflective array changes uniformly with frequency.

[0066] Figure 5 This demonstrates the relationship between the normalized reflection phase of a reflective element and its height. The reflection phase can vary and reach or exceed 360°. A linear fit, "phase = -80h + 397", can be used to construct the aperture of the reflective array.

[0067] Figure 6 A schematic diagram of an antenna 100 according to an embodiment of the present invention during incident wave transmission is shown. The incident wave is transmitted by a horn antenna 610 at an angle θ. iDirected to antenna 100. In a carefully designed reflective array, all reflected waves should point in the same direction, thus producing a pencil beam 620.

[0068] After obtaining the relationship between the reflection phase and the unit height, phase compensation can be achieved by changing the height of the particles. The F / D ratio is usually set to 0.8 to 1.2. Here, the F / D value is chosen to be 1. The phase distribution of the reflection array can be calculated by the position and focal length of the reflection unit, as shown in formula (1).

[0069]

[0070] F x = f×sin(θ) i ),F y =0

[0071] F z = f×cos(θ) i ),P z =h+t

[0072] Where k is the wave number, (F x ,F y ,F z ) are the coordinates of the focus, (P) x ,P y ,P z ) represents the position of the reflecting unit. (P) x ,P y () represents the coordinates of the central reflective element, h represents the height of the reflective element, and t represents the thickness of the support layer. This is the initial reflection phase of the reflecting unit. The incident angle is the angle between the reflection array and the center of the feed phase, which is set to be symmetrical with respect to the main beam, i.e., 15°.

[0073] According to formula (1), the phase distribution of the reflection array can be obtained. If at a frequency of 29 GHz... Then the reflection phase of each reflecting unit can be obtained, such as Figure 7 As shown. Next, by comparing this result with that from... Figure 5 By combining the relationship between the phase and h obtained from the simulation, the entire structure of the reflection array can be simulated, such as... Figure 7 As shown.

[0074] By pointing an incident wave at a 15° angle to the antenna using a standard gain horn antenna, the antenna performance of an ADM-based reflector array can be obtained. However, as... Figure 7 As shown, the phase compensation at the center of the reflector array 710 is not zero, which will cause a phase jump from 360° to 0° near the center. To eliminate this phenomenon, the following settings are made: The central phase is the phase compensation of the central reflecting element. The reflection array demonstrates an optimized phase distribution. From Figure 7 It can be seen that the optimized version has an actual gain ratio of approximately 2dB, while the former has a simulated actual gain of 24.5dBi.

[0075] In one embodiment, a linearly polarized standard-gain fed horn antenna was fabricated and measured. Its measured and simulated -10 dB impedance bandwidth typically covers the entire frequency range of interest (26.5–40 GHz). The actual antenna gain (including mismatch) of the fed horn antenna varies between 13.5 and 16.1 dBi across the entire frequency range. At 29 GHz, the antenna gain is 14.7 dBi. The edge taper of the horn antenna illumination is approximately -10 dB.

[0076] For experimental purposes, an antenna prototype was fabricated and measured. The reflector array structure was obtained using 3D printing technology, with the reflector elements made of DK12 material and the support layer made of DK3 material. Two mounting platforms were required to fix the model on the system's turntable, one for the elevation plane and one for the azimuth plane. These platforms were also fabricated using PLA material via 3D printing technology, with a dielectric constant of 2.2. The normalized radiation pattern and antenna gain were tested using a far-field measurement system.

[0077] Figure 8a A prototype schematic of antenna 100 in the azimuth plane is shown. As the turntable rotates 820° in the xoz plane, the azimuth plane can be scanned, with the main beam in the azimuth plane located at a 15° direction. However, due to equipment limitations, the turntable 820 cannot rotate in the azimuth plane.

[0078] When the model was rotated 90° in the xoz plane to measure the radiation pattern in the azimuth plane, incorrect results were found, as with traditional testing methods. This is because the radiation wave is not in the azimuth plane in this condition. To measure the azimuth plane radiation pattern, another support platform 830 was designed, such as... Figure 8b As shown. Due to its wedge-shaped structure, the main beam can appear in the 0° direction, so the main beam can be scanned when the turntable 830 is rotated.

[0079] Figure 9a An optical image of one embodiment of antenna 100 is shown, while Figure 9b A close-up of the antenna 100 is shown, with detailed views of each reflective element 101. Multiple reflective elements are arranged in an array on the support layer to form a reflective array panel, with the arm portions of adjacent reflective elements 101 in contact with each other.

[0080] Figure 10 and 11The simulated and measured normalized gain of the reflector array in the elevation and azimuth planes are displayed. Due to alignment errors in the measurement system, the measured main beam is along the -14° direction, which is 1° smaller than the simulated angle (-15°). In the elevation plane, the measured sidelobe and backlobe levels are below -12.5 and -12 dB, respectively, which are in excellent agreement with the simulated results of -12 and -13 dB. In the azimuth plane, the measured backlobe level is below -20 dB, which is in excellent agreement with the simulated result of -23 dB. Furthermore, in both planes, the measured and simulated cross-polarization are below -20 dB, indicating that the reflector array has good polarization isolation performance at 29 GHz. The measurement differences in the elevation and azimuth planes are due to alignment errors and 3D printing accuracy errors.

[0081] Figure 12 The measured and simulated actual gains at 29 GHz are shown. It can be observed that the maximum measured actual gain is 23.8 dBi, which is 0.7 dBi lower than the simulated gain. The 1 dB reflection bandwidth for both the measured and simulated values ​​is 10.5%. and 10.6% All measurement results are in excellent agreement with the simulation results.

[0082] In summary, embodiments of the present invention provide an ADM-based reflective antenna array with a simple structure that can operate in the Ka-band. The reflective antenna array element is a two-armed cylinder with a dielectric constant of 12. Compared to traditional dielectric reflective antennas using an all-metal grounding layer, the present invention achieves phase adjustment by changing the element height while maintaining broadband reflection. Based on the Mie resonance principle, by appropriately selecting parameters, the electrical and magnetic resonance points will be separated, thus forming a reflection window. In this way, a high-performance reflective antenna can be achieved using a single-layer dielectric and a simple element structure. A hexagonal prototype with dimensions of 19cm * 12cm was designed, manufactured, and tested. Measured radiation modes confirmed that the antenna exhibits excellent performance, with a peak gain of 23.8dBi and a 1dB reflectivity of 10.5% (27–30 GHz).

[0083] While embodiments have been described and illustrated in detail above, they should also be considered illustrative rather than restrictive, as exemplary embodiments have been shown only and do not limit the scope of the invention in any way. It is understood that any feature described herein can be used with any embodiment. Illustrative embodiments are not mutually exclusive, nor do they exclude other embodiments not described in this specification. Therefore, the invention also provides embodiments that include combinations of one or more of the illustrative embodiments described above. Modifications and alterations to the invention described herein may be made without departing from the spirit and scope of the invention; therefore, only the limitations set forth in the appended claims should be applied.

Claims

1. An antenna, comprising: (i) A support layer having a first dielectric constant; as well as (ii) A reflective element disposed on the support layer, the reflective element being configured to reflect the incident wave with a corresponding reflection phase; and the reflective element having a second dielectric constant, the second dielectric constant being higher than the first dielectric constant; The reflective unit extends vertically from the support layer, its height is configured to achieve the corresponding reflection phase, and both the support layer and the reflective unit are formed of an all-dielectric material; and the reflective unit is a single-layer structure.

2. The antenna according to claim 1, wherein the reflecting element further comprises: (i) Central part; and (ii) Two arm portions, connected to either side of the central portion; The arm portions form a 180° angle with each other.

3. The antenna of claim 2, wherein the central portion has a first height, and each of the arm portions has a second height, wherein the second height is less than half of the first height.

4. The antenna according to claim 3, wherein the first height is between 3 mm and 7 mm.

5. The antenna according to claim 3, wherein the second height is 2.5 mm.

6. The antenna of claim 2, wherein the central portion is aligned with the support layer on the same central axis.

7. The antenna of claim 2, wherein each of the arm portions extends from the central portion along the electric field direction.

8. The antenna according to claim 2, wherein the central portion is cylindrical.

9. The antenna of claim 8, wherein the width of each arm portion is smaller than the diameter of the central portion.

10. The antenna according to claim 8, wherein the radius of the central portion is 2.15 mm.

11. The antenna according to claim 2, wherein the support layer is hexagonal.

12. The antenna of claim 11, wherein each of the arm portions is aligned with the edge of the support layer.

13. The antenna of claim 12, wherein each of the arm portions has a width that is substantially one-third the width of the edge of the support layer.

14. The antenna of claim 13, wherein the width of each arm portion is 1 mm.

15. The antenna of claim 11, wherein the support layer has a diagonal length of 10 mm.

16. The antenna of claim 2, wherein the antenna is symmetrical about a center of rotation.

17. The antenna of claim 1, wherein the antenna is configured to operate within a reflection bandwidth defined by the interval between the magnetic resonant frequency and the electromagnetic resonant frequency.

18. The antenna of claim 17, wherein the reflection bandwidth is determined by the width of the reflection element.

19. The antenna of claim 17, wherein the reflection bandwidth is determined by the height of the reflection element.

20. The antenna of claim 1, wherein the antenna is formed by three-dimensional printing technology.

21. The antenna of claim 1, wherein the antenna is configured to operate in the Ka band or THz band.

22. The antenna according to claim 1, comprising a plurality of reflective elements arranged in an array on the support layer, wherein, The plurality of reflecting units are configured to together form a predetermined phase distribution pattern to reflect incident waves in a predetermined direction.

Images