Folding transmission array antenna, communication module and electronic equipment

Abstract

The invention discloses a folding transmission array antenna, a communication module and electronic equipment, and belongs to the technical field of antennae, the antenna comprises a transmission surface, a reflection polarization conversion surface, a feed source and a plurality of support pillars, the transmission surface is provided with a plurality of transmission array units, the reflection polarization conversion surface is provided with a plurality of reflection polarization conversion metasurface units, and the support pillars are arranged on the transmission array units. The reflective polarization conversion metasurface unit is made of a near-zero refractive index metamaterial; the transmission array unit is composed of a first dielectric plate, a second dielectric plate, a first metal layer, a second metal layer and a third metal layer; the reflection polarization conversion metasurface unit comprises a third dielectric plate and a metal plate, and a fourth metal layer and a fifth metal layer are arranged on the two faces of the third dielectric plate respectively; the communication module adopts the antenna; the electronic equipment adopts the antenna. The antenna profile is further compressed under the condition that the geometric position of the feed source is not changed, meanwhile, feed source blocking is avoided, high gain can be kept in a specific frequency band, and the dual requirements of a modern communication system for antenna miniaturization and high performance are met.

Description

Technical Field

[0001] This application belongs to the field of antenna technology, and in particular relates to a folded transmission array antenna, a communication module, and an electronic device. Background Technology

[0002] With the increasing demands for high gain, wide bandwidth, and miniaturization in wireless communication and radar systems, antenna size reduction and low profile design have become critical issues that urgently need to be addressed. While traditional transmit array (TA) antennas offer advantages such as high gain, low cost, and simple structure, they require a certain spatial separation between the feed and the transmit array to ensure effective wave propagation and phase compensation, resulting in a high physical profile. To address this high profile issue, researchers have proposed folded transmit array (FTA) designs, which involve repeatedly folding the electromagnetic wave transmission path using ray tracing principles. For example, in a multi-layered structure, folding the beam path three times can reduce the antenna profile to one-third of its original height. However, folded designs often suffer from feed obstruction problems: when the feed is located at the aperture plane, it blocks some radiation, potentially leading to increased sidelobes, reduced efficiency, and other performance degradation. Summary of the Invention

[0003] This application aims to address the challenge of simultaneously achieving both miniaturization and high performance in traditional antennas. To this end, this application provides a folded transmission array antenna, a communication module, and an electronic device. Based on a broadband low-profile folded transmission array antenna (NZIM-FTA) made of near-zero refractive index metamaterial (NZIM), the antenna profile is further compressed without altering the feed geometry, while avoiding feed obstruction. This allows it to maintain high gain within a specific frequency band, meeting the dual requirements of modern communication systems for antenna miniaturization and high performance.

[0004] In a first aspect, embodiments of this application provide a folded transmission array antenna, which includes:

[0005] The transmission surface is equipped with several transmission array elements;

[0006] The reflective polarization conversion surface is provided with several reflective polarization conversion metasurface units, which are made of near-zero refractive index metamaterials.

[0007] The feed source is positioned at the center of the polarization conversion reflection polarization conversion surface;

[0008] Several support columns connect and fix the polarization conversion reflective polarization conversion surface and the transmission array metasurface layer, so that the distance between the transmission surface and the reflective polarization conversion surface is 7-15mm;

[0009] The transmission array unit is composed of a first dielectric substrate, a second dielectric substrate, a first metal layer, a second metal layer, and a third metal layer; the first metal layer and the third metal layer are mutually orthogonal grid structures; the second metal layer is a metal patch structure located between the first dielectric substrate and the second dielectric substrate.

[0010] The reflective polarization conversion metasurface unit comprises a third dielectric plate and a metal plate, both of the same size and arranged at intervals. The third dielectric plate has a fourth metal layer and a fifth metal layer on its two sides respectively; the fourth metal layer and the fifth metal layer are both arranged axially symmetrically.

[0011] In some embodiments, the fourth metal layer and the fifth metal layer each include a non-closed metal ring and an inner circle pattern disposed within the metal ring. The central angle corresponding to the opening of the non-closed metal ring of the reflective polarization conversion metasurface unit is 10° to 40°. The inner circle pattern includes a central pattern located at the center of the circle and an extended short arm extending outward from the central pattern. The extended short arm is symmetrical about the horizontal axis of symmetry and the vertical axis of symmetry of the central pattern.

[0012] In some embodiments, an air gap with a height of 0.5 mm ± 0.1 mm is left between the third dielectric plate and the metal plate of the reflective polarization conversion metasurface unit.

[0013] In some embodiments, the second metal layer of the transmission array unit is shaped as a slotted ring, the center of which coincides with the center of the transmission array unit, the slots coincide with the main diagonal of the transmission array unit, the four endpoints of the slotted ring extend into the circle as long metal arms, and the two intersections of the secondary diagonal of the transmission array unit and the ring extend into the circle as short metal arms.

[0014] In some embodiments, the angle between the middle gap of the second metal layer slotted annulus of the transmission array unit and the metal grid of the third metal layer is a rotation angle β, which ranges from –90° to +90°.

[0015] In some embodiments, the metal grid width of the first metal layer and the third metal layer is 0.75mm ± 0.1mm, and the slot width of the second metal layer is 0.3mm ± 0.1mm.

[0016] In some implementations, the reflective polarization conversion metasurface units are arranged in an N*(N+1) array, where N is a natural number greater than or equal to 17, and the value is determined based on the aperture size and the unit period.

[0017] In some implementations, the transmission array elements are arranged in an N*N array, where N is a natural number greater than or equal to 17, and the value is determined based on the matching of the aperture size and the element period.

[0018] Secondly, embodiments of this application also provide a communication module for a folded transmission antenna, which includes the folded transmission array antenna described above in this invention.

[0019] Thirdly, embodiments of this application also provide an electronic device for communicating with external devices, the electronic device including the folded transmission array antenna described above.

[0020] As can be seen from the above technical solution, the beneficial effects of this application are as follows:

[0021] 1. This invention introduces a near-zero refractive index metamaterial, with the transmission surface serving as the antenna's main radiating surface. This generates near-zero phase accumulation. Utilizing the phase compensation characteristics of the transmission array elements and the beam collimation characteristics of the reflective polarization conversion surface in synergy, and through the placement of support pillars, the energy density of the reflected wave is significantly concentrated between the transmission elements and the reflective polarization conversion surface. This facilitates beam focusing by the reflective polarization conversion surface, resulting in a significant reduction in the physical profile of the folded transmission array antenna. This avoids feed obstruction problems without altering the feed geometry. While achieving an ultra-low profile structure, high gain and broadband performance are still maintained. This provides a feasible solution for compact, high-performance wireless communication systems.

[0022] 2. The communication module of the present invention, by adopting the above-mentioned folded transmission array antenna, can reduce its own size and expand its application range when combined with other electronic devices.

[0023] 3. The electronic device of the present invention, using the above-mentioned folded transmission array antenna, can maintain high gain and broadband data communication performance when interacting with other devices, while also facilitating the compact design of the electronic device to a certain extent. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced one by one below. Obviously, the accompanying drawings described below are some embodiments of this application. For those skilled in the art, other embodiments and drawings can be obtained based on these drawings without creative effort. The flowcharts shown in the accompanying drawings are merely illustrative and do not necessarily include all content and operations / steps, nor do they necessarily have to be performed in the described order. For example, some operations / steps can be decomposed, while some operations / steps can be combined or partially combined. Therefore, the actual execution order may change according to the actual situation.

[0025] Figure 1 A partial cross-sectional schematic diagram of the overall structure of the folded transmission array antenna provided by the present invention;

[0026] Figure 2This is a schematic diagram of the structure of the reflective polarization conversion metasurface unit provided by the present invention;

[0027] Figure 3 The structure of the transmission array unit provided by the present invention;

[0028] Figure 4 A top view schematic diagram of the reflective polarization conversion metasurface unit provided by the present invention;

[0029] Figure 5 The NZIM equivalent dielectric constant provided by this invention;

[0030] Figure 6 The NZIM equivalent permeability provided by this invention;

[0031] Figure 7 The NZIM equivalent refractive index provided by this invention;

[0032] Figure 8 The cross-polarization conversion reflection amplitude of NZIM provided by this invention;

[0033] Figure 9 The power flow distribution of NZIM-RPCS near 17.6 GHz provided by this invention;

[0034] Figure 10 The power flow distribution of NZIM-RPCS near 20.1 GHz provided by this invention;

[0035] Figure 11 This is a partial top view of the transmission array unit provided by the present invention;

[0036] Figure 12 This is a partial top view of the transmission array unit provided by the present invention;

[0037] Figure 13 The transmission amplitude and phase of the transmission array element proposed in this invention;

[0038] Figure 14 The transmission amplitude and phase of the transmission array element proposed in this invention at different incident angles θ;

[0039] Figure 15 The figures show the |S11| and gain curves of the folded transmission array antenna proposed in the invention, respectively.

[0040] Figure 16 The figures show the |S11| and gain curves of the folded transmission array antenna proposed in the invention, respectively.

[0041] Figure 17 The E-plane radiation pattern of the folded transmission array antenna provided by the present invention near 17.6 GHz;

[0042] Figure 18 The H-plane radiation pattern of the folded transmission array antenna provided by the present invention near 17.6 GHz;

[0043] Figure 19 The E-plane radiation pattern of the NZIM-FTA near 20.1 GHz provided by this invention;

[0044] Figure 20 The images show the H-plane radiation pattern of the folded transmission array antenna provided by this invention near 20.1 GHz.

[0045] Reference numerals: 100, Transmission surface; 110, Transmission array element; 111, First dielectric plate; 112, Second dielectric plate; 113, First metal layer; 114, Second metal layer; 1141, Slitted ring; 1142, Long metal arm; 1143, Short metal arm; 115, Third metal layer; 1151, Metal grid; 200, Reflection polarization conversion surface; 210, Reflection polarization conversion metasurface element; 211, Third dielectric plate; 212, Metal plate; 213, Fourth metal layer; 2131, Non-closed metal ring; 2132, Central pattern; 2133, Extended short arm; 214, Fifth metal layer; 300, Feed source; 400, Support column. Detailed Implementation

[0046] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. The detailed description of the embodiments of this application provided in the drawings is not intended to limit the scope of the claimed application. The described embodiments are only a part of the embodiments of this application, not all of them. Based on the embodiments in this application, they can be arranged and designed in various different configurations. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0047] This application is described below with reference to the accompanying drawings and specific embodiments:

[0048] This application provides a folded transmission array antenna, such as... Figure 1 , Figure 2 and Figure 3As shown, the antenna includes: a transmission surface 100, a reflection polarization conversion surface 200, a feed source 300, and several support columns 400. The transmission surface 100 is a square plate, with several transmission array elements 110 on each of its two sides. Specifically, multiple transmission array elements 110 are arranged in an array on the surface of the transmission surface 100. The transmission surface 100 is the main radiating surface of the antenna, used to introduce the required phase compensation, thereby achieving planarization and directivity control of the outgoing wavefront. The reflection polarization conversion surface 200 is a square plate, with several reflection polarization conversion metasurface elements 210 on each of its two sides. Specifically, multiple reflection polarization conversion metasurface elements 210 are arranged in an array on the surface of the reflection polarization conversion surface 200. The reflection polarization conversion metasurface elements 210 are made of near-zero refractive index metamaterials, such as polytetrafluoroethylene plates (F4BM-2) with a relative permittivity of 2.65, a loss tangent of 0.0007, and a thickness of 1 mm. The main function of the reflective polarization conversion surface 200 is to generate near-zero phase accumulation, thereby achieving an equivalent beam focusing effect. The feed 300, located at the center of the reflective polarization conversion surface 200, is used to transmit or receive electromagnetic waves and is a conventional design. Several support columns 400 connect and fix the reflective polarization conversion surface 200 and the transmission surface 100. The support columns 400 use existing nylon columns, screws, etc. Threaded holes are provided at the four corners of both the transmission surface 100 and the reflective polarization conversion surface 200. These four nylon columns connect and fix the transmission surface 100 and the reflective polarization conversion surface 200, creating an air gap between them. The size of this air gap is 7–15 mm. Using this gap range, the energy density of the reflected wave is significantly concentrated, resulting in a strong beam focusing capability.

[0049] The transmission array unit 110, constituting the transmission phase compensation surface, is formed by printing metal patterns on both sides of the transmission surface 100. It consists of a first dielectric substrate 111, a second dielectric substrate 112, a first metal layer 113, a second metal layer 114, and a third metal layer 115. Both the first dielectric substrate 111 and the second dielectric substrate 112 are made of polytetrafluoroethylene (PTFE) plates (F4BM-2) with a relative permittivity of 2.65, a loss tangent of 0.0007, and a thickness of 1 mm. The metal layer is made of copper and has a thickness of 0.035 mm. The first metal layer 113 and the third metal layer 115 form an orthogonal lattice structure for reflecting common-polarized waves; the second metal layer 114 is a metal patch structure located between the first dielectric substrate 111 and the second dielectric substrate 112, used to adjust the transmission phase and enhance bandwidth.

[0050] The reflective polarization conversion metasurface unit 210, constituting the reflective polarization conversion metasurface, is formed by printing metal patterns on both sides of the reflective polarization conversion surface 200. It includes a third dielectric plate 211 and a metal plate 212, both of the same size and arranged at intervals. The third dielectric plate 211 is made of polytetrafluoroethylene (PTFE) plate (F4BM-2) with a relative permittivity of 2.65, a loss tangent of 0.0007, and a thickness of 1 mm. The metal plate 212 is made of copper and has a thickness of 0.035 mm. A fourth metal layer 213 and a fifth metal layer 214 are respectively provided on both sides of the third dielectric plate 211. The metal layers are made of copper and have a thickness of 0.035 mm; both the fourth metal layer 213 and the fifth metal layer 214 are arranged axially symmetrically.

[0051] This invention introduces a near-zero refractive index metamaterial, with the transmission surface 100 serving as the antenna's main radiating surface. This generates near-zero phase accumulation. Utilizing the phase compensation characteristics of the transmission array element 110 and the beam collimation characteristics of the reflective polarization conversion surface 200 in synergy, and through the placement of the support pillar 400, the energy density of the reflected wave is significantly concentrated between the transmission element and the reflective polarization conversion surface 200. This facilitates beam focusing by the reflective polarization conversion surface 200, resulting in a significant reduction in the physical profile of the folded transmission array antenna. This avoids the obstruction problem of the feed 300 without altering its geometric position. While achieving an ultra-low profile structure, high gain and broadband performance are still maintained. This provides a feasible solution for compact, high-performance wireless communication systems.

[0052] In some implementations, the distance between the transmission surface 100 and the reflection polarization conversion surface 200 is equal to the height of the air cavity, forming an air gap, i.e., the working profile height H of the antenna. In this embodiment, H can be selected as 9 mm, approximately 0.58 times the free-space wavelength λ0 at the operating center frequency of 19.5 GHz. This distance is the optimal value after simulation optimization. To ensure the versatility and adjustability of the antenna structure, the recommended distance range is 7–15 mm, corresponding to 0.45–0.85 times λ0. Within this range, the phase compensation of the TA element can still effectively achieve the conversion of spherical waves to plane waves. When the distance is too small (<7 mm), the cavity is difficult to form an effective beam reconstruction region; when the distance is too large (>15 mm), the profile height will increase significantly, losing the design advantage of a low profile. Therefore, the reasonable distance between the NZIM and the TA element should be controlled within the above recommended range.

[0053] like Figure 2 and Figure 4As shown, in some embodiments, the fourth metal layer 213 and the fifth metal layer 214 have the same structure, each including a non-closed metal ring 2131 and an inner circular pattern disposed within the metal ring, both in patch form. The non-closed metal ring 2131 is a ring with a notch, and the central angle corresponding to the opening is 10° to 40°. For example, the gap width w of the non-closed metal ring 2131 is 0.3 mm, the outer radius r1 is 2.9 mm, the inner radius r2 is 2.3 mm, and the opening angle α is 20°, which is beneficial to achieving anisotropic response of the structure, thereby endowing it with polarization conversion capability. The inner shape of the circle includes a central shape 2132 located at the center of the circle and extending short arms 2133 extending outward from the central shape 2132. The extending short arms 2133 are symmetrically arranged with respect to the horizontal and vertical axes of symmetry of the central shape 2132; that is, multiple sets of extending short arms 2133 are connected to the central shape 2132. Each set includes two parallel, spaced extending short arms 2133, which extend outward from the central shape 2132. These multiple sets of extending short arms 2133 are symmetrically arranged in multiple directions, such as... Figure 2 The array period p = 6 mm, the dielectric layer thickness t = 1 mm, the central figure 2132 is a square with a side length a of 1.4 mm, the length b of the extended short arm 2133 is 1.2 mm, and the width c of the extended short arm 2133 is 0.35 mm. Two extended short arms 2133 form a group, for a total of four groups. Two groups of extended short arms 2133 are positioned opposite each other and are symmetrical about the horizontal axis of symmetry of the central figure 2132. The other two groups of extended short arms 2133 are positioned opposite each other and are symmetrical about the vertical axis of symmetry of the central figure 2132. The horizontal axis of symmetry is the axis of symmetry of a side of the central figure 2132, and the vertical axis of symmetry is the axis of symmetry of the adjacent side of a side of the central figure 2132.

[0054] In this application, the metallic patterns on both surfaces of the reflective polarization conversion metasurface 200 (NZIM) have non-closed metallic rings 2131, with a 20° notch (α = 20°) introduced along the diagonal direction of the rings. This notch-shaped slit design breaks the geometric symmetry of the rings, causing the current distribution and resonant mode of the reflective polarization conversion metasurface unit 210 to differ in the x-axis and y-axis directions, thereby introducing anisotropy in the equivalent dielectric / magnetic response. Specifically, when an x-polarized wave is incident, because the current path along the ring is continuous in the x-direction but interrupted in the y-direction by the slit, different induced currents and equivalent polarization responses are formed in the x and y directions. This anisotropy leads to polarization coupling when the electromagnetic wave propagates inside the unit, causing the incident wave to generate a portion of cross-polarization components after reflection, thus completing the polarization conversion.

[0055] In some embodiments, an air gap is left between the third dielectric plate 211 and the metal plate 212 of the reflective polarization conversion metasurface unit 210, for example, the air gap height is 0.5 mm. The metal plate 212 is made of copper clad laminate, and the metal plate 212 has the same dimensions as the dielectric plate. The unit's effective equivalent electromagnetic parameters are extracted using S-parameter inversion technology, exhibiting ENZ characteristics (effective relative permittivity ε) at 17.47 GHz. eff =0.003-0.052i, equivalent refractive index n = 0.075-0.092i), exhibiting MNZ characteristics at 20.1 GHz (effective relative permeability μ). eff =0.026-0.034i, refractive index n = 0.12+0.08i), such as Figure 5 , Figure 6 and Figure 7 As shown, this indicates that the structure can achieve near-zero refractive index characteristics at both frequencies, thereby generating near-zero phase accumulation at these two frequencies and achieving an equivalent beam-focusing effect.

[0056] like Figure 8 As shown, this unit also possesses significant polarization conversion capability. Within the 16.75–20.9 GHz range, the amplitude of the reflection coefficient Ryx, which converts an x-polarized incident wave to a y-polarized component after reflection, is greater than 0.9, and the x-component of Rx is less than 0.2, indicating high polarization conversion efficiency and ensuring the cross-polarization characteristics of the reflected wave. The aforementioned x-polarization and y-polarization refer to waves where the electric field vector is linearly aligned along the x or y direction. In simulations, if the electric field incident direction is the x-axis (E along the x-direction), it is called an x-polarized wave. When the reflected wave's electric field is mainly aligned along the y-axis, it is said to have been converted to y-polarization. Ryx is the cross-polar component in the reflection coefficient matrix, representing the ability of an x-polarized incident wave to be reflected into a y-polarized wave. Figure 9 and Figure 10 The results show that at a height of H=9mm, the energy density of the reflected wave is significantly concentrated, further verifying its beam focusing capability. Figure 9 and Figure 10 The distribution of power flow (i.e., the Poynting vector) on the NZIM-RPCS surface is shown at 17.6 GHz and 20.1 GHz, respectively. The energy density is clearly concentrated in one direction, indicating that the reflected wave is directionally focused and phase-consistent, achieving beam focusing. This proves that the NZIM layer not only converts polarization during reflection but also provides near-zero phase delay, forming collimated reflection.

[0057] The principle behind this functionality is as follows: When electromagnetic waves propagate in a medium with a near-zero equivalent refractive index (n≈0), due to the phase constant β=k0·n→0 (where k0 is the free-space wavenumber), the wave experiences almost no additional phase change during propagation. For the reflective surface formed by NZIM cells, when electromagnetic waves are transmitted from the TA layer and reflected by the NZIM-RPCS, their propagation path includes two passages through the air cavity and one local propagation within the NZIM layer. Since n≈0 in NZIM, no phase difference is generated during wave propagation within the layer, ensuring phase consistency at each reflection point and achieving a planar wavefront effect. Furthermore, this zero-phase-difference reflection is equivalent to all reflected waves exiting from a "virtual plane," effectively forming a quasi-planar reflective surface. According to the wavefront superposition principle, when multiple phase-consistent reflected waves are superimposed in front, a main beam with high directionality and concentrated energy is formed, achieving a "beam focusing" effect.

[0058] The aforementioned ENZ characteristic refers to the near-zero dielectric constant, ε. eff ≈0 indicates that the equivalent permittivity of the material approaches zero. At this point, the electric field distribution in the structure hardly changes, and the wave propagates in a quasi-static manner. The MNZ characteristic refers to the near-zero permeability, μ eff ≈0 indicates that the equivalent permeability approaches zero. At this point, the magnetic field distributes slowly in the structure, leading to a propagation constant approaching zero. When n=√(ε·μ)≈0, the refractive index is close to zero, meaning the wave propagation speed in the material approaches infinity, and the phase shift is almost zero, exhibiting a "no phase accumulation" characteristic. In this application, the NZIM unit structure constructed using double-sided metallic patterns achieves ENZ and MNZ behaviors at two different frequency points, thereby providing "zero phase shift reflection" in the folded transmission array path. Combined with 100° phase compensation of the transmission surface, broadband high-gain quasi-plane wave radiation output is achieved.

[0059] like Figure 3 and Figure 11As shown, in some embodiments, the second metal layer 114 of the transmission array unit 110 is a metal patch, such as a patch structure evolved from a double-slotted ring resonator (DSRR). Its shape is a slotted ring 1141, the center of which coincides with the center of the transmission array unit 110, and the slots coincide with the main diagonal of the transmission array unit 110. The slotted ring 1141 is formed by two symmetrically arranged semi-rings spaced apart. Four metal long arms 1142 extend inward from the four endpoints of the slotted ring 1141, forming four metal long arms 1142 in total. Each pair of metal long arms 1142 is collinear and parallel. Two metal short arms 1143 extend inward from the two intersection points of the secondary diagonal of the transmission array unit 110 and the ring, forming two collinear metal short arms 1143. The metal short arms 1143 are perpendicular to the metal long arms 1142. This arrangement allows for adjustment of the transmission phase and enhancement of the bandwidth. Figure 3 The array period p = 6 mm, the dielectric layer thickness t = 1 mm, the inner radius r4 of the slotted ring 1141 is 2.3 mm, the outer radius r3 is 2.7 mm, the width g of the two slots is 0.3 mm, there are 4 metal long arms 1142, each with a length d1 of 2.5 mm and a width w1 of 0.3 mm, and there are 2 metal short arms 1143, each with a length d2 of 1.05 mm and a width w2 of 0.4 mm.

[0060] In some embodiments, the angle between the middle gap of the slotted annulus 1141 of the second metal layer 114 of the transmission array unit 110 and the metal grid 1151 of the third metal layer 115 is a rotation angle β, ranging from –90° to +90°, such as 45°. The rotation angle β can be used to achieve unit-level phase control. The β angle is the rotation angle of the transmission patch structure relative to the horizontal coordinate system. Counterclockwise rotation from the positive x-axis is defined as the positive direction. β = 0° indicates that the patch structure has not rotated, and β = ±45° indicates a 45° rotation around the center. Different β angles correspond to different transmission phases, achieving unit-level phase control.

[0061] like Figure 3 and Figure 12 As shown, in some embodiments, the metal grid 1151 of the first metal layer 113 and the third metal layer 115 of the transmission array unit 110 has the same width, and the space between the first metal layer 113 and the second metal layer 114, and between the second metal layer 114 and the third metal layer 115, is an F4BM-2 substrate (ε). r=2.65, tanδ=0.0007), the metal grids 1151 of the first metal layer 113 and the third metal layer 115 are arranged at equal intervals, and the metal grids 1151 of the first metal layer 113 and the third metal layer 115 are arranged in orthogonal directions to reflect common polarized waves. For example, the metal width g1 of the metal grid 1151 is 0.75mm, and the interval g2 is 0.75mm. The first metal layer 113, the second metal layer 114 and the third metal layer 115 are all made of copper material and adopt standard PCB manufacturing process.

[0062] In some embodiments, the feed source 300 is located at the center of the reflective polarization conversion surface 200 at the bottom of the air cavity, employs a microstrip slot patch structure, and is fed through an SMA coaxial probe. The inner pin of the SMA coaxial connector passes through the wall and is connected to the feed source 300. The feed source 300 is printed on an Arlon AD255C substrate with a thickness of 0.762 mm, a dielectric constant of 2.55, and a loss tangent of 0.001. It is tightly coupled to the reflective polarization conversion surface 200 to improve reflection efficiency. To avoid obstruction by the feed 300, the feed 300 radiates upwards and propagates through a double-folded path with the upper transmission array via the reflective polarization conversion surface 200. After reflection by the NZIM layer, the beam becomes orthogonally polarized, but a portion of the wavefront remains spherical. Each element in the transmission array 110 is designed with a rotation angle β based on its distance Δr from the source point, achieving phase difference compensation of Δφ≈–k·Δr, making the outgoing wavefront more planar. Finally, phase compensation achieves main beam focusing. After radiation from the feed 300, the beam is first reflected back to the NZIM surface by the upper transmission surface 100, where polarization conversion and phase preservation occur before it passes through the upper layer again, forming a forward high-gain output beam. All dielectric layers have a copper plating thickness of 0.035mm for easy standardized PCB processing and manufacturing.

[0063] In some implementations, to improve the intermediate frequency operating bandwidth and directivity, a printed metal frame, typically a continuous annular pattern made of copper foil with a width of approximately 0.5–1 mm, is placed around the perimeter of the transmission array unit 110. This enhances the coupling characteristics of the edge units, effectively increases the main lobe gain, and suppresses side lobe leakage, particularly significantly improving pattern stability in the 17.5–21.5 GHz range. During assembly, structural accuracy can be maintained by appropriately selecting the position and material of the support pillars 400. For example, nylon support pillars 400 offer electromagnetic transparency, good mechanical strength, and stable insulation, avoiding the introduction of parasitic metal coupling and controlling frequency drift caused by assembly. Furthermore, during actual measurements, it was found that the near-zero phase characteristics of the reflective polarization conversion metasurface unit 210 (NZIM unit) have a crucial impact on the overall radiation performance. If the structure of the reflective polarization conversion metasurface unit 210 experiences a slight shift, it needs to be corrected by re-optimizing the phase compensation angle of the transmission array unit 110 to maintain pattern symmetry and axial ratio performance. The aforementioned phase compensation is achieved as follows: the reflective polarization conversion metasurface unit 210 is a collimated surface, and its phase invariance to the reflected wave depends on the structural symmetry and periodicity of the unit array. If there is a local positional shift, a slight distortion will occur in the reflected wavefront, causing the beam focusing to deviate. In this case, it is necessary to finely compensate for the phase difference Δφ by locally adjusting the β angle of the transmission array unit 110 (TA unit) to restore the pattern symmetry and axial ratio consistency. This adjustment is usually achieved through simulation optimization or manual fine-tuning compensation.

[0064] Simulations were performed using an antenna with the aforementioned reflective polarization conversion metasurface element 210 and transmission array element 110, according to an embodiment of this application. Simulation results show that within a bandwidth of 14.2–28.9 GHz, the transmission coefficient S21 amplitude is greater than 0.9, indicating high transmission efficiency; the phase change is approximately linear, achieving a phase modulation range covering 360°. Figure 13 As shown. This unit exhibits good stability to changes in the incident angle, such as... Figure 14 As shown, under an incident angle variation within the range of 0°–30°, the transmission phase error of the TA element remains within ±8°, with a transmission amplitude greater than 0.9 and a variation less than 0.05, indicating excellent stability to the incident angle, with the transmission phase and amplitude remaining essentially unchanged. Therefore, this structure demonstrates good angular stability and is suitable for large-aperture folded transmission array antennas. In this invention, the TA element is located at the top of the antenna, forming the main radiating surface. Its function is to introduce the required phase compensation into the cross-polarized beam after folding through the NZIM layer, thereby achieving planarization and directivity control of the outgoing wavefront. The phase compensation characteristics of the transmission array element 110 work synergistically with the beam collimation characteristics of the NZIM layer to ensure high overall antenna gain and broadband performance within a limited profile height.

[0065] The transmission array element (TA) used in this application has independent phase adjustment capability. Its key control parameters are the geometric dimensions of the center patch, the length of the symmetrical arm, the opening direction, and the rotation angle β. Since the antenna feed 300 transmits spherical waves, the distances from different transmission array elements 110 to the feed 300 are different, resulting in spatial differences in the original phase distribution. These differences must be compensated to form a plane wave with a consistent phase at the output surface, achieving beam collimation and gain enhancement. To achieve this goal, this application calculates the corresponding ideal compensation phase Δφ = –k·Δr (where k is the wave number) based on the distance Δr from the center of each element to the phase center point of the feed 300. The required transmission phase difference is then achieved by adjusting the structural parameters of the element (mainly the β angle). Since the transmission phase of the element structure has an approximately linear relationship with the β angle, precise transmission phase control of 0–360° can be achieved simply by selecting an appropriate β value. Finally, through phase compensation of each element in the entire array, the spherical wave can be transformed into a plane wave with a consistent direction after passing through the transmission array, thereby forming a highly directional main beam in the far field. The synergistic mechanism between the NZIM-RPCS and the upper transmission array (TA) constitutes the core technological innovation of this invention. The NZIM structure provides low-profile beam collimation capability near two near-zero frequency points, while the upper TA structure performs precise wavefront correction and direction maintenance across the entire aperture plane through a broadband phase compensation mechanism. This "dual-peak collimation + broadband compensation" design strategy enables the antenna to achieve a low profile while possessing high gain and directivity stability in the 17–21 GHz frequency band.

[0066] In some embodiments, the reflective polarization conversion metasurface unit 210 is arranged in an N*(N+1) array, where N is a natural number greater than or equal to 17, such as 17, 20, 35, etc., and its value is determined based on the matching of the aperture size and the unit period. For example, with a unit period of 6 mm, the near-zero refractive index metamaterial reflector (NZIM-RPCS) uses a 17×18 arrangement, and N is 17. The array arrangement, with the array size determined by matching the aperture size and the unit period, ensures antenna directivity and gain performance while also considering structural compactness and manufacturing feasibility. In some embodiments, the transmission array unit 110 is arranged in an N*N array, where N is a natural number greater than or equal to 17, such as 17, 20, 35, etc., and its value is determined based on the matching of the aperture size and the unit period. For example, with a unit period of 6 mm, the transmission array (TA) unit array uses a 17×17 arrangement, and N is 17.

[0067] The folded transmission array antenna embodiment of this application has an antenna size of 102mm × 102mm, a folded cavity height H of 9mm, and an overall H / D ratio of approximately 0.088, which is far lower than the level of existing antenna designs. Performance tests were conducted near a center frequency of 19.5GHz. Despite the significantly reduced profile, this antenna still maintains high gain and wide bandwidth performance. The experiments were conducted in a reflection-free anechoic chamber and included reflection coefficient testing, gain testing, and far-field pattern measurement. The experimental results show that the proposed antenna's 10dB reflection coefficient bandwidth covers 17.5GHz to 21.5GHz, achieving an operating bandwidth of 4GHz. Figure 15 As shown, the reflection coefficient (S11) is less than -10dB, the operating frequency range is 17.5GHz–21.5GHz, and the bandwidth reaches 4GHz, indicating good impedance matching performance. Figure 16 As shown, the measured peak gain is 21.32 dBi, the peak aperture efficiency reaches 30.1%, and the 1.5 dB gain bandwidth is 14.8%. The radiation pattern test results are as follows... Figure 17 , Figure 18 , Figure 19 , Figure 20 The measured peak gain is 21.32 dBi, and the aperture efficiency is 30.1%. The main lobe of the E / H plane radiation pattern matches the simulation well, and the sidelobe level is below -11 dB. The main lobe direction is stable, the beam is narrow, and the beamwidth is controlled within ±7°. These are all quantitative indicators of "good" performance. Therefore, the main lobe directions of the E and H planes of the antenna at the two typical frequencies of 17.6 GHz and 20.1 GHz match the simulation well, proving that the antenna has good directivity and beam control capabilities. This shows that the antenna maintains excellent radiation performance while achieving an ultra-low profile structure, balancing high performance and compact design.

[0068] The advantages of this application are:

[0069] 1. This application leverages the zero-phase-shift characteristic of near-zero refractive index metamaterials (NZIMs). Electromagnetic waves incident on the surface of a NZIM from any direction can be emitted in phase almost perpendicular to the metamaterial's exit interface after passing through the NZIM, thus achieving beam convergence and high-gain performance. Furthermore, this application designs a transmission surface 100 or a reflection polarization conversion surface 200 to achieve beam collimation and phase convergence without increasing the transmission path length. This compresses the antenna profile without altering the geometry of the feed 300, while simultaneously avoiding obstruction by the feed 300. In summary, this application significantly reduces the profile of the transmission array antenna while ensuring high gain and bandwidth.

[0070] 2. This application introduces NZIM elements into the reflective polarization conversion surface 200, utilizing their zero phase shift characteristics and polarization conversion capability to compress the antenna profile to less than 1 / 3 of the focal length, reducing the height-to-diameter ratio (H / D) to below 0.1. Simultaneously, the antenna maintains high gain in the 17.5–21.5 GHz frequency band, with a measured peak gain of 21.32 dBi and a 1.5 dB gain bandwidth covering 14.8%, aiming to meet the dual demands of modern communication systems for miniaturized and high-performance antennas.

[0071] 3. This application is manufactured using planar printing technology, which has the advantages of low cost and easy integration.

[0072] 4. The reflective polarization conversion metasurface unit 210 of this application can achieve near-zero refractive index characteristics at both frequency points, thereby generating near-zero phase accumulation at these two frequency points and achieving an equivalent beam-focusing effect. In addition, this unit also has significant polarization conversion capability and beam-focusing capability.

[0073] 5. The transmission array element 110 of this application can be used to adjust the transmission phase and enhance the bandwidth.

[0074] 6. The transmission array element 110 of this application has good angular stability and is suitable for large-aperture folded transmission array antennas.

[0075] 7. The transmission array element 110 of this application has high transmission efficiency and approximately linear phase change, and can achieve a phase adjustment range covering 360°.

[0076] Secondly, this application also provides a communication module including a folded transmission array antenna, which includes the folded transmission array antenna designed in this invention. In the communication module, the folded transmission array antenna can be configured with different parameters: the NZIM unit and TA unit have a certain degree of structural substitutability. Without changing the basic working principle, adjustments can be made to structural parameters such as the metal patch, non-closed metal ring 2131, extended short arm 2133, metal short arm 1143, metal long arm 1142, slot, and angle. Within a reasonable range, the operating frequency, polarization conversion efficiency, and near-zero refractive index performance can be adjusted. Recommended parameter ranges are: patch side length 1.2–1.8 mm, arm length 1.0–1.5 mm, and slot angle 10°–40°. Furthermore, the shape of the central patch can also be replaced with a cross, hexagon, ellipse, or other structures, as long as the required equivalent electromagnetic parameters (ε) are maintained. eff ≈0, μ eff The TA unit has a high polarization conversion efficiency (|Ryx|>0.9). Similarly, the structure of the TA unit can be replaced with other metasurface structures with high transmittance and continuous phase control capabilities, provided that a phase coverage of 0–360° and a transmission amplitude greater than 0.9 are achieved in the target frequency range.

[0077] The communication module of the present invention adopts the above-mentioned folded transmission array antenna, which can reduce its size. When combined with other electronic devices, the communication module has wide applicability and can be combined with other frequency bands. Different forms of transmission array unit 110, reflection polarization conversion metasurface unit 210 and feed 300 can also be designed as needed, which can be flexibly designed and expand the scope of application.

[0078] Thirdly, embodiments of this application also provide an electronic device for communicating with external devices. The electronic device includes the folded transmission array antenna described above. The electronic device includes a mobile terminal or a fixed hardware terminal. Mobile terminals include mobile phones, drones, tablets, and smartwatches, while fixed hardware terminals include wireless routers, wireless monitoring equipment, and vehicle-mounted electrical appliances.

[0079] This application also provides an electronic device for communicating with external devices. The electronic device includes the folded transmission array antenna described above. The electronic device can be applied in various fields, such as wireless communication, radar, and satellite communication, where high reversibility and compact structures are required.

[0080] Regarding the specific implementation methods of this application, it should be noted that:

[0081] In the description of this application, the terms "comprising," "including," or any other variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, apparatus, or readable storage medium that comprises a list of elements includes not only those elements but also other elements not expressly listed that conform to the concept of this application, or elements inherent to such a process, method, apparatus, or readable storage medium. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of additional elements in the process, method, apparatus, or readable storage medium that includes said element.

[0082] In the description of this application, the use of terms such as "some embodiments," "optional embodiments," "example," "specific example," "optional example," or "optional embodiment," etc., indicates that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application, but does not imply that these embodiments illustrate and describe all possible forms of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0083] The present invention has been described in detail above with reference to specific embodiments and exemplary examples. The above description is exemplary and not exhaustive, and is not limited to the disclosed embodiments; the above description should not be construed as a limitation of the present invention. Technical solutions between various embodiments can be combined with each other, but must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed in this application. Although embodiments of the present application have been shown and described, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present application. Those skilled in the art will understand that various other specific changes and combinations of embodiments based on the technical teachings disclosed in this application, without departing from the essence of the present application, are still within the scope of protection defined by the claims of the present invention and their equivalent technical solutions.

Claims

1. A folded transmission array antenna, characterized in that, include: The transmission surface (100) is provided with a plurality of transmission array elements (110); The reflective polarization conversion surface (200) is provided with a plurality of reflective polarization conversion metasurface units (210), wherein the reflective polarization conversion metasurface units (210) are made of NZIM near-zero refractive index metamaterial; The feed (300) is positioned at the center of the reflective polarization conversion surface (200); A plurality of support columns (400) are provided, the support columns (400) connecting and fixing the reflective polarization conversion surface (200) and the transmission surface (100), such that the distance between the transmission surface (100) and the reflective polarization conversion surface (200) is 7-15 mm; The transmission array unit (110) is composed of a first dielectric substrate (111), a second dielectric substrate (112), a first metal layer (113), a second metal layer (114), and a third metal layer (115); the first metal layer (113) and the third metal layer (115) are mutually orthogonal grid structures; the second metal layer (114) is a metal patch structure located between the first dielectric substrate (111) and the second dielectric substrate (112); The reflective polarization conversion metasurface unit (210) includes a third dielectric plate (211) and a metal plate (212), both of the same size and arranged at intervals. The two sides of the third dielectric plate (211) are respectively provided with a third metal layer (115) and a fourth metal layer (213); the third metal layer (115) and the fourth metal layer (213) are both arranged axially symmetrically.

2. The folded transmission array antenna according to claim 1, characterized in that, The fourth metal layer (213) and the fifth metal layer (214) each include a non-closed metal ring (2131) and an inner circle pattern disposed within the metal ring. The central angle corresponding to the opening of the non-closed metal ring (2131) is 10° to 40°. The inner circle pattern includes a central pattern (2132) located at the center of the circle and an extended short arm (2133) extending outward from the central pattern (2132). The extended short arm (2133) is symmetrical about the horizontal axis of symmetry and the vertical axis of symmetry of the central pattern (2132).

3. The folded transmission array antenna according to claim 1, characterized in that, An air gap with a height of 0.5 mm ± 0.1 mm is left between the third dielectric plate (211) and the metal plate (212) of the reflective polarization conversion metasurface unit (210).

4. The folded transmission array antenna according to claim 1, characterized in that, The metal patch is shaped as a slotted ring (1141). The center of the slotted ring (1141) coincides with the center of the transmission array unit (110). The slot coincides with the main diagonal of the transmission array unit (110). The four endpoints of the slotted ring (1141) extend into the circle as long metal arms (1142). The two intersection points of the secondary diagonal of the transmission array unit (110) and the ring extend into the circle as short metal arms (1143).

5. The folded transmission array antenna according to claim 1, characterized in that, The angle between the gap in the middle of the slit ring (1141) of the second metal layer (114) and the metal grid (1151) of the third metal layer (115) is the rotation angle β, which ranges from –90° to +90°.

6. The folded transmission array antenna according to claim 5, characterized in that, The width of the metal grid (1151) of the first metal layer (113) and the third metal layer (115) is 0.75mm±0.1mm, and the width of the slit of the second metal layer (114) is 0.3mm±0.1mm.

7. The folded transmission array antenna according to claim 1, characterized in that, The reflective polarization conversion metasurface unit (210) is arranged in an N*(N+1) array, where N is a natural number greater than or equal to 17, and its value is determined according to the matching of the aperture size and the unit period.

8. The folded transmission array antenna according to claim 7, characterized in that, The transmission array unit (110) is arranged in an N*(N) array, where N is a natural number greater than or equal to 17, and its value is determined according to the matching of the aperture size and the unit period.

9. A communication module for a folded transmission array antenna, characterized in that, Includes the folded transmission array antenna as described in any one of claims 1-8.

10. An electronic device, characterized in that, For communicating with external devices, the electronic device includes the folded transmission array antenna according to any one of claims 1-8.

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