Optical transparent linearly polarized millimeter wave reflective array based on low-loss dielectric substrate

Abstract

The invention discloses an optical transparent linear polarization millimeter wave reflective array based on a low-loss dielectric substrate, and belongs to the field of electronic devices of wireless communication systems. The reflective array antenna units adopt two-dimensional triangular periodic arrangement, array sparsification and sidelobe suppression requirements are considered, the light transparency of the antenna is improved by adopting the metal grids for reducing the metal area and the full-transparent dielectric material, the transparency of the antenna is improved while the electromagnetic performance is ensured, the full-planar design is adopted in the design process, and the design cost is reduced. All metal structures transmit energy through electromagnetic coupling, so that the processing complexity is effectively reduced, and the problems of transparency reduction and the like caused by metal via holes are avoided. The optical transparent reflective array antenna has good transparency, is easy to integrate, and has a wide application prospect in the field of satellite communication.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic devices for wireless communication systems, and in particular to an optically transparent linearly polarized millimeter wave reflector array based on a low-loss dielectric substrate. Background Art

[0002] With the rapid development of 5G / 6G communications and satellite communications, high-frequency millimeter-wave spectrum resources have become the core carrier supporting ultra-high-speed communications. However, high-frequency signals suffer from limited coverage and susceptibility to obstruction. To overcome this bottleneck, the industry has proposed an "ultra-dense networking" technology approach. This involves deploying large-scale phased array antenna systems in base stations, satellite terminals, and mobile devices, building intelligent reflective surfaces (RIS) to enhance signal diffraction capabilities. In this context, traditional metal antennas present an irreconcilable contradiction. On the one hand, scenarios such as building curtain walls and vehicle-mounted platforms place rigid demands on antennas to be visually invisible and spatially integrated. The high reflectivity of metal structures not only undermines the architectural aesthetics but also generates electromagnetic interference. On the other hand, satellite terminals require large-scale arrays of thousands of elements within a limited area. The size of metal antennas severely restricts deployment flexibility. This has driven revolutionary innovation in optically transparent electronics. By integrating high-frequency millimeter-wave communications with transparent electronics processes, these devices address the integration and functionality conflicts of traditional antennas and are key components of future smart surfaces and communication networks.

[0003] According to the literature, there are no known Q / V-band optically transparent reflectarray antennas. Reflectarray antennas, thanks to their planar structure, ease of fabrication, and lack of a complex feed network, often enable large array sizes and high gain. Existing reflectarray antennas evolved from traditional curved metal reflectarray antennas, achieving different beamformation through phase modulation and reflection of the energy transmitted by the feed source. Existing optically transparent reflectarray antennas are often derived from reflectarray antennas made transparent. Commonly used transparent antennas typically utilize transparent materials such as meshed metal, transparent conductive materials, and transparent dielectrics to achieve optical transparency. Phase control methods for optically transparent reflectarray antennas fall into two main categories: the first utilizes discrete phase control through resonant structures, such as transparent resonant metal rings, achieving phase control through specific resonant modes and multi-layer cascades. The second utilizes continuous phase control through phase shifter structures, such as delay lines. Delay lines of varying lengths can achieve different phase states. Compared to the first approach, the second approach offers greater bandwidth, fewer stacked structures, and, consequently, higher transparency. However, it also requires a larger unit cell space for the phase shifter. Summary of the Invention

[0004] The present invention provides an optically transparent linearly polarized millimeter-wave reflective array based on a low-loss dielectric substrate. The array adopts a fully planar structure with a low profile and a simple structure. While achieving phase modulation of the incident wave, it has good optical transparency and has broad application prospects in the field of satellite communications.

[0005] An embodiment of the present invention provides an optically transparent linearly polarized millimeter-wave reflectarray based on a low-loss dielectric substrate, comprising a feed source and an optically transparent reflective array. Reflectarray antenna units are arranged on the optically transparent reflective array in a triangular periodic array at the vertices of an equilateral triangle grid. The diameter of the optically transparent reflective array is D, and the vertical distance from the feed source to the reflectarray antenna units is F, where 0.6≤F / D≤1.5.

[0006] Optionally, in one embodiment of the present invention, the side length of the regular triangle grid is 0.3 to 0.4 wavelengths of electromagnetic waves in free space.

[0007] Optionally, in one embodiment of the present invention, the reflectarray antenna unit has a stacked structure, including eighteen layers including metal layers and dielectric layers, including five metal layers, six OCA adhesive layers, and seven dielectric layers, wherein the seven dielectric layers include four polyethylene terephthalate films and three modified cycloolefin polymer films; the eighteen layers, from top to bottom, are respectively a first metal layer, a first polyethylene terephthalate layer, a first OCA adhesive layer, a second polyethylene terephthalate layer, a second metal layer, a second OCA adhesive layer, a third polyethylene terephthalate layer, a third OCA adhesive layer, a first modified cycloolefin polymer layer, a fourth OCA adhesive layer, a fourth polyethylene terephthalate layer, a third metal layer, a fifth OCA adhesive layer, a second modified cycloolefin polymer layer, a fourth metal layer, a sixth OCA adhesive layer, a fifth metal layer, and a third modified cycloolefin polymer layer;

[0008] The reflectarray antenna unit is divided into a radiation layer, a slot-coupled feeding layer, and a phase-shifting layer. From top to bottom, the 1st to 11th layers are radiation layers, the 12th layer is a slot-coupled feeding layer, and the 13th to 18th layers are phase-shifting layers.

[0009] Optionally, in one embodiment of the present invention, the overall thickness of the light-transparent reflective front is 0.17-0.2λ0, where λ0 is the free space wavelength.

[0010] Optionally, in one embodiment of the present invention, the first metal layer and the second metal layer correspond to a metal grid line width w1 of 5μm to 20μm and a spacing l1 of 50μm to 300μm, the fourth metal layer and the fifth metal layer correspond to a metal grid line width w1 and a spacing l1, the third metal layer has a metal grid line width w1 and a spacing of l1, and the metal grid is ±45 degrees to the edge of the structure.

[0011] Optionally, in one embodiment of the present invention, the first metal layer includes an upper gridded metal rectangular stacked patch, the second metal layer includes a lower gridded metal rectangular stacked patch, the third metal layer corresponds to a gridded metal ground, the fourth metal layer includes a gradient microstrip line matching branch, a section of gridded gradient microstrip line, an upper portion of a gridded out-of-plane Marchand balun, and an upper portion of a gridded open-circuit out-of-plane differential delay line phase shifter, and the fifth metal layer includes a lower portion of a gridded out-of-plane Marchand balun and a lower portion of a gridded open-circuit out-of-plane differential delay line phase shifter.

[0012] Optionally, in one embodiment of the present invention, the metal structure of the reflectarray antenna unit includes an upper gridded metal rectangular patch, a lower gridded metal rectangular patch, a partial ground grid with a line width of w1 and a spacing of l1, a projection grid of the upper gridded metal patch with a line width of w1 and a spacing of l1 on the third metal layer, a projection grid of the lower gridded metal patch with a line width of w1 and a spacing of l1 on the third metal layer, a gridded open-circuit out-of-plane differential time delay line phase shifter with a line width of w1 and a spacing of l1 on the third metal layer, and a gridded out-of-plane Marcha nd balun projected grid on the third metal layer, gridded gradient microstrip line with line width w1 and spacing l1 projected grid on the third metal layer, gradient microstrip line matching branch projected grid on the third metal layer, "I"-shaped gap, gradient microstrip line matching branch, gridded gradient microstrip line with line width w1 and spacing l1, gridded out-of-plane Marchand balun with line width w1 and spacing l1, gridded open-circuit out-of-plane differential delay line phase shifter with line width w1 and spacing l1, where the line width w1 is 5μm~20μm and the spacing l1 is 50μm~300μm.

[0013] Optionally, in one embodiment of the present invention, a metal layer is etched on a polyethylene terephthalate film and a modified cycloolefin polymer substrate, an upper gridded metal rectangular patch is etched on the upper surface of the first polyethylene terephthalate layer, a lower gridded metal rectangular patch is etched on the lower surface of the second polyethylene terephthalate layer, a gridded metal ground is etched on the lower surface of the fourth polyethylene terephthalate layer, a gridded gradient microstrip line is etched on the lower surface of the second modified cycloolefin polymer layer, a gridded out-of-plane Marchand balun single-line to differential delay line structure is etched on the lower surface of the second modified cycloolefin polymer layer and the upper surface of the third modified cycloolefin polymer layer, and a gridded open-circuit out-of-plane differential delay line phase shifter structure is also etched on the lower surface of the second modified cycloolefin polymer layer and the upper surface of the third modified cycloolefin polymer layer.

[0014] Optionally, in one embodiment of the present invention, the gridded out-of-plane Marchand balun is composed of a section of gridded microstrip line, a pair of gridded open-circuited out-of-plane bent microstrip line branches with the same width as the microstrip line, and a gridded open-circuited out-of-plane differential delay line connected in parallel with the branches. The gridded microstrip line and the gridded open-circuited bent microstrip line are coupled through a narrow gap, and there is no electrical connection between the three metal structures.

[0015] Optionally, in one embodiment of the present invention, the gridded gradient microstrip line and the gridded off-plane Marchand balun in the fourth metal layer and the fifth metal layer are electrically connected by metal, and the gridded off-plane Marchand balun and the gridded open-circuit off-plane differential delay line phase shifter are electrically connected by metal, and the length of the gridded open-circuit off-plane differential delay line is changed to continuously change the reflection phase provided by the unit.

[0016] The optically transparent linearly polarized millimeter-wave reflectarray based on a low-loss dielectric substrate in an embodiment of the present invention utilizes a metal grid with reduced metal area and fully transparent dielectric materials to improve the antenna's optical transparency, enhancing transparency while maintaining electromagnetic performance. A fully planar design is employed, with all metal structures transmitting energy through electromagnetic coupling, effectively reducing processing complexity and avoiding issues such as reduced transparency caused by metal vias. The optically transparent reflectarray antenna of the present invention offers good transparency and ease of integration, promising broad application prospects in satellite communications.

[0017] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0019] Figure 1 A schematic diagram of an optically transparent linearly polarized millimeter-wave reflective array based on a low-loss dielectric substrate according to an embodiment of the present invention;

[0020] Figure 2 Schematic diagram of the stacked structure of the modified cycloolefin polymer-based linearly polarized light transparent reflective antenna array unit in Example 1;

[0021] Among them, 1 is the first metal layer, 2 is the first polyethylene terephthalate layer, 3, 6, 8, 10, 13, and 16 are OCA adhesive layers, 4 is the second polyethylene terephthalate layer, 5 is the second metal layer, 7 is the third polyethylene terephthalate layer, 9 is the first modified cycloolefin polymer layer, 11 is the fourth polyethylene terephthalate layer, 12 is the third metal layer, 14 is the second modified cycloolefin polymer layer, 15 is the fourth metal layer, 17 is the fifth metal layer, and 18 is the third modified cycloolefin polymer layer;

[0022] Figure 3 Schematic diagram of each metal layer of the modified cycloolefin polymer-based linearly polarized light transparent reflective antenna array unit in Example 1;

[0023] Among them, 1a is a meshed metal patch with an upper line width of w1 and a grid spacing of l1, 5a is a meshed metal patch with a second line width of w1 and a grid spacing of l1, 12a is a partial grid with a line width of w1 and a spacing of l1, 12b is a projection grid of a meshed metal patch with an upper line width of w1 and a grid spacing of l1 on the third metal layer, 12c is a projection grid of a meshed metal patch with a lower line width of w1 and a grid spacing of l1 on the third metal layer, 12d is a projection grid of a meshed open-circuit out-of-plane differential delay line phase shifter with a line width of w1 and a grid spacing of l1 on the third metal layer, 12e is a mesh with a line width of w1 and a grid spacing of l1 The projected grid of the gridded out-of-plane Marchand balun on the third metal layer, 12f is the projected grid of the gridded graded microstrip line with a line width of w1 and a grid spacing of l1 on the third metal layer, 12g is the projected grid of the graded microstrip line matching branch on the third metal layer, 12h is an "I"-shaped gap, 15a is the graded microstrip line matching branch, 15b is the gridded graded microstrip line with a line width of w1 and a grid spacing of l1, 15c and 17a are gridded out-of-plane Marchand baluns with a line width of w1 and a grid spacing of l1, and 15d and 17b are gridded open-circuit out-of-plane differential delay line phase shifters with a line width of w1 and a grid spacing of l1;

[0024] Figure 4 The reflection coefficient variation curves of the modified cycloolefin polymer-based linearly polarized light transparent reflective antenna array unit in the range of 42 GHz to 52 GHz in Example 1 are given as a function of frequency at normal incidence from main polarization to main polarization at different types of delay line lengths;

[0025] Figure 5 The reflection coefficient variation curve from main polarization to cross polarization with frequency for the linearly polarized light transparent reflective antenna array unit of modified cycloolefin polymer based on Example 1 in the range of 42 GHz to 52 GHz at normal incidence and different types of delay line lengths is given;

[0026] Figure 6The curves of the reflection phase variation from main polarization to main polarization with frequency for the linearly polarized light transparent reflective antenna array unit of modified cycloolefin polymer based on Example 1 in the range of 42 GHz to 52 GHz at normal incidence and different types of delay line lengths are given;

[0027] Figure 7 The reflection coefficient variation curves of the modified cycloolefin polymer-based linearly polarized light transparent reflective antenna array unit in the range of 42 GHz to 52 GHz in Example 1 at different types of delay line lengths from main polarization to main polarization when incident at a 40° elevation angle are given;

[0028] Figure 8 The reflection coefficient variation curve from main polarization to cross polarization with frequency for the modified cycloolefin polymer-based linearly polarized light transparent reflective antenna array unit in the range of 42 GHz to 52 GHz in Example 1 at an incidence angle of 40° is given at different types of delay line lengths;

[0029] Figure 9 The main polarization beam scanning pattern of the modified cycloolefin polymer-based linearly polarized light transparent reflective antenna array at 46 GHz in Example 1 is given. DETAILED DESCRIPTION

[0030] The following describes embodiments of the present invention in detail, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and are not to be construed as limiting the present invention.

[0031] Figure 1 Schematic diagram of an optically transparent linearly polarized millimeter-wave reflective array based on a low-loss dielectric substrate provided according to an embodiment of the present invention.

[0032] like Figure 1 As shown, the optically transparent linearly polarized millimeter-wave reflector array based on a low-loss dielectric substrate includes a feed source (I) and an optically transparent reflective array surface (II); the reflector array antenna units are arranged in a triangular periodic array on the optically transparent reflective array surface (II) at the vertices of an equilateral triangle grid, wherein the side length of the equilateral triangle grid is 0.3 to 0.4 wavelengths of electromagnetic waves in free space, the diameter of the optically transparent reflective array surface is D, which is 64 mm in the embodiment, and the vertical distance from the feed source to the reflector array antenna units is F, wherein 0.6≤F / D≤1.5, which is 1.3 in the embodiment.

[0033] like Figure 2As shown, the reflective array antenna unit includes 18 layers of metal layers and dielectric layers, which can be roughly divided into radiation layers, slot coupling feeding layers, and phase shifting layers. The 18 layers include 5 metal layers, which are, from top to bottom, the first metal layer (1), the second metal layer (5), the third metal layer (12), the fourth metal layer (15), and the fifth metal layer (17), 6 OCA adhesive layers (3, 6, 8, 10, 13, and 16), and 7 dielectric layers. The dielectric layers include four layers of polyethylene terephthalate film, three layers of modified cycloolefin polymer film, and, from top to bottom, the first polyethylene terephthalate film, the second metal layer (5), the third metal layer (12), the fourth metal layer (15), and the fifth metal layer (17). The invention relates to a polyol layer (2), a second polyethylene terephthalate layer (4), a third polyethylene terephthalate layer (7), a first modified cycloolefin polymer layer (9), a fourth polyethylene terephthalate layer (11), a second modified cycloolefin polymer layer (14), and a third modified cycloolefin polymer layer (18), wherein the first to the eleventh layers constitute a radiation layer, the twelfth layer is a slot-coupled feed layer, and the thirteenth to the eighteenth layers constitute a phase shift layer. The overall thickness of the light-transparent reflective array is 0.17 to 0.2λ0, where λ0 is the free space wavelength. In the embodiment, the overall thickness of the unit is 1.03 mm.

[0034] Specifically, the metal layer is etched on the polyethylene terephthalate film and the modified cycloolefin polymer substrate, the upper gridded metal rectangular patch is etched on the upper surface of the first polyethylene terephthalate layer, the lower gridded metal rectangular patch is etched on the lower surface of the second polyethylene terephthalate layer, the gridded metal ground is etched on the lower surface of the fourth polyethylene terephthalate layer, the gridded gradient microstrip line is etched on the lower surface of the second modified cycloolefin polymer layer, the gridded out-of-plane Marchand balun single-line to differential delay line structure is etched on the lower surface of the second modified cycloolefin polymer layer and the upper surface of the third modified cycloolefin polymer layer, and the gridded open-circuit out-of-plane differential delay line phase shifter structure is also etched on the lower surface of the second modified cycloolefin polymer layer and the upper surface of the third modified cycloolefin polymer layer.

[0035] The 1st and 5th layers correspond to the metal grid line width w1 (5μm~20μm) and the spacing l1 (50μm~300μm), the 15th and 17th layers correspond to the metal grid line width w1 and the spacing l1, the 12th layer has a metal grid line width w1 and a spacing of l1, and the metal grid is ±45 degrees to the edge of the structure.

[0036] Specifically, if Figure 3As shown, the unit metal structure includes: a first metal layer including an upper gridded metal rectangular stacked patch (1a), a second metal layer including a lower gridded metal rectangular stacked patch (5a), a third metal layer corresponding to a gridded metal ground (12a-12h), a fourth metal layer including a gradient microstrip line matching branch (15a), a section of a gridded gradient microstrip line (15b), a gridded out-of-plane Marchand balun upper layer portion (15c) and a gridded open-circuit out-of-plane differential delay line phase shifter upper layer portion (15d), and a fifth metal layer including a gridded out-of-plane Marchand balun lower layer portion (17a) and a gridded open-circuit out-of-plane differential delay line phase shifter lower layer portion (17b).

[0037] The unit metal structure includes an upper grid metal rectangular stacked patch (1a), a lower grid metal rectangular stacked patch (5a), a partial grid (12a) with a line width of 5μm to 20μm and a spacing of 50μm to 300μm, a projection grid (12b) of the upper grid metal patch with a line width w1 (5μm to 20μm) and a spacing l1 (50μm to 300μm) on the third metal layer, and a lower grid metal rectangular stacked patch (5a). m), and a spacing of l1 (50μm to 300μm) on the third metal layer, a projection grid (12c) of a lower layer gridded metal patch on the third metal layer, a projection grid (12d) of a gridded open circuit non-planar differential delay line phase shifter on the third metal layer with a line width of w1 (5μm to 20μm) and a spacing of l1 (50μm to 300μm), and a gridded non-planar Ma The projection grid (12e) of the rchand balun on the third metal layer, the projection grid (12f) of the gridded gradient microstrip line with line width w1 (5μm~20μm) and spacing l1 (50μm~300μm) on the third metal layer, the projection grid (12g) of the gradient microstrip line matching branches on the third metal layer, the "I" shaped gap (12h), the gradient microstrip line matching branches (15a), the line width w1 (5μm~20 μm) and a spacing of l1 (50μm to 300μm), a gridded gradient microstrip line (15b) with a line width of w1 (5μm to 20μm) and a spacing of l1 (50μm to 300μm), a gridded out-of-plane Marchand balun (15c and 17a) with a line width of w1 (5μm to 20μm) and a spacing of l1 (50μm to 300μm), and a gridded open-circuit out-of-plane differential delay line phase shifter (15d and 17b) with a line width of w1 (5μm to 20μm) and a spacing of l1 (50μm to 300μm).

[0038] Specifically, the modified cycloolefin polymer layer and the polyethylene terephthalate layer are connected by an OCA adhesive layer, mainly connecting the fourth polyethylene terephthalate layer and the second modified cycloolefin polymer layer; the polyethylene terephthalate layer and the modified cycloolefin polymer layer are connected by an OCA adhesive layer, mainly connecting the third and fourth polyethylene terephthalate layers and the first modified cycloolefin polymer layer; the polyethylene terephthalate layer and the polyethylene terephthalate layer are connected by an adhesive layer, mainly connecting the first, second and third polyethylene terephthalate layers; OCA material is filled between the modified cycloolefin polymer layer and the modified cycloolefin polymer layer, mainly connecting the second and third modified cycloolefin polymer layers.

[0039] Specifically, the gridded metal ground in the third metal layer includes a partial grid (12a) with a line width of 5 μm to 20 μm and a spacing of 50 μm to 300 μm, a projection grid (12b) of an upper gridded metal patch with a line width w1 (5 μm to 20 μm) and a spacing l1 (50 μm to 300 μm) on the third metal layer, a projection grid (12c) of a lower gridded metal patch with a line width w1 (5 μm to 20 μm) and a spacing l1 (50 μm to 300 μm) on the third metal layer, and a grid (12d) of a lower gridded metal patch with a line width w1 (5 μm to 20 μm) and a spacing l1 (50 μm to 300 μm) on the third metal layer. μm) on the third metal layer (12d), a gridded out-of-plane differential time delay line phase shifter with a line width of w1 (5μm to 20μm) and a spacing of l1 (50μm to 300μm) on the third metal layer (12e), a gridded gradient microstrip line with a line width of w1 (5μm to 20μm) and a spacing of l1 (50μm to 300μm) on the third metal layer (12f), a gridded gradient microstrip line matching branch on the third metal layer (12g), and an "I"-shaped gap (12h).

[0040] Specifically, the gridded out-of-plane Marchand balun consists of a gridded microstrip line, a pair of gridded open-circuited out-of-plane bent microstrip line branches with the same width as the microstrip line, and a gridded open-circuited out-of-plane differential delay line connected in parallel with the branches. The gridded microstrip line and the gridded open-circuited bent microstrip line are coupled through a narrow gap, and there is no electrical connection between the three metal structures.

[0041] Specifically, the gridded gradient microstrip line and the gridded out-of-plane Marchand balun are electrically connected by metal in the fourth and fifth metal layers, and the gridded out-of-plane Marchand balun and the gridded open-circuit out-of-plane differential delay line phase shifter are electrically connected by metal. Changing the length of the gridded open-circuit out-of-plane differential delay line can continuously change the reflection phase provided by the unit.

[0042] The unique out-of-plane Marchand balun structure can effectively realize the function of common-mode conversion to differential mode to reduce the loss caused by modified cyclic olefin polymer. The reflectarray antenna uses an open-circuit out-of-plane differential delay line phase shifter, which forms a double delay through open-circuit reflection, significantly reducing the volume of the phase shifter and the metal area, and realizes continuous phase control by controlling the different lengths of the delay line.

[0043] The present invention discloses a modified cycloolefin polymer baseline polarized light-transparent reflective array antenna operating at 43GHz to 51GHz. The reflective array antenna unit adopts a two-dimensional triangular periodic arrangement, taking into account the requirements of array sparsification and sidelobe suppression. The antenna unit proposed in the present invention is composed of a laminated patch, a coupling slot, an off-plane Marchand balun, and an open-circuit off-plane delay line phase shifter. The change of the delay line of different lengths can realize the control of the unit phase. The present invention adopts a metal grid with reduced metal area and a fully transparent dielectric material to improve the optical transparency of the antenna, thereby improving the antenna transparency while ensuring electromagnetic performance. The present invention adopts a fully planar design in the design process, and all metal structures transfer energy through electromagnetic coupling, which effectively reduces the processing complexity and avoids the problems of reduced transparency caused by metal vias. The light-transparent reflective array antenna of the present invention has good transparency and is easy to integrate, and has broad application prospects in the field of satellite communications.

[0044] The optically transparent linearly polarized millimeter-wave reflective array based on a low-loss dielectric substrate of the present invention is described in detail below through a specific embodiment.

[0045] Example 1

[0046] like Figure 1 As shown, the present invention proposes a modified cycloolefin polymer baseline polarized light-transparent reflective array antenna, which includes a linearly polarized feed source I and a light-transparent reflective array II. The diameter of the light-transparent reflective array II is D, which is 64 mm in the embodiment. The vertical distance from the feed source to the array surface is F, and the value of F / D is between 0.6 and 1.5, which is 1.3 in the embodiment. The reflective array unit covers 43 GHz to 51 GHz, and its structure is fully planar, with a low profile and good light transparency. The units are arranged in an equilateral triangle periodic pattern and placed at the vertices of the equilateral triangle. The side length of the equilateral triangle corresponds to 0.3λ to 0.4λ, and λ is the free space wavelength, which is 2.18 mm in the embodiment.

[0047] Details of the metal structure of each layer are as follows Figure 3As shown, the grid line width in the first and second metal layers is w1 (5μm to 20μm) and the grid spacing is l1 (50μm to 300μm). The grid line width in the fourth and fifth metal layers is w1 and the grid spacing is l1. The third metal layer also has a grid line width w1 and a grid spacing l1. The metal grids are at ±45 degrees to the edge of the structure. In this embodiment, the metal grids corresponding to the first metal layer 1 and the second metal layer 5 are selected with a line width of 10μm and a spacing of 100μm. The metal grids corresponding to the fourth metal layer 15 and the fifth metal layer 17 are selected with a line width of 10μm and a spacing of 100μm. The metal grids of the fifth metal layer 12 are selected with a line width of 10μm and 100μm. The first metal layer includes an upper patch 1a, the second metal layer includes a lower patch 5a; the third metal layer includes a ground grid 12a with a line width of 10μm and a spacing of 100μm, a projection grid 12b of the upper gridded metal patch with a line width of 10μm and a spacing of 100μm on the third metal layer, a projection grid 12c of the lower gridded metal patch with a line width of 10μm and a spacing of 100μm on the third metal layer, a projection grid 12d of a gridded open-circuit out-of-plane differential delay line phase shifter with a line width of 10μm and a spacing of 100μm on the third metal layer, a projection grid 12e of a gridded out-of-plane Marchand balun with a line width of 10μm and a spacing of 100μm on the third metal layer, a gridded gradient microstrip line with a line width of 10μm and a spacing of 100μm on the third metal layer. The metal layer includes a projected grid 12f, a projected grid 12g of the gradient microstrip line matching branch on the third metal layer, and an I-shaped gap 12h; the fourth metal layer includes a gradient microstrip line matching branch 15a, a gridded gradient microstrip line 15b with a line width of 10μm and a spacing of 100μm, a gridded out-of-plane Marchand balun upper part 15c with a line width of 10μm and a spacing of 100μ, and a gridded open-circuit out-of-plane differential delay line phase shifter upper part 15d with a line width of 10μm and a spacing of 100μ; the fifth metal layer includes a gridded out-of-plane Marchand balun lower part 17a with a line width of 10μm and a spacing of 100μm, and a gridded open-circuit out-of-plane differential delay line phase shifter lower part 17b with a line width of 10μm and a spacing of 100μm. In the present invention, when the unit is actually operating, the gridded laminated patch receives electromagnetic waves radiated from space and transmits them through the coupling slots to the gridded tapered microstrip line. The tapered microstrip line matching branches adjust the matching to maximize the transmission of the electromagnetic waves to the gridded tapered microstrip line. In the present invention, the final line width of the gridded tapered microstrip line is consistent with the line width of the gridded off-plane Marchand balun input end. The electromagnetic waves propagate along the gridded tapered microstrip line until they are transmitted to the gridded off-plane Marchand balun, where the gridded balun converts the electromagnetic waves from the microstrip mode to the differential mode as accurately as possible.The present invention utilizes a gridded, open-circuit, out-of-plane differential delay line phase shifter. Electromagnetic waves propagate continuously along the delay line, with their phase changing continuously according to the differential transmission line pattern. This propagation process ends with an open-circuit reflection at the end, returning along the original path of the delay line, generating a double delay, and finally radiating outward. This gridded, open-circuit, out-of-plane differential delay line phase shifter significantly reduces the phase shifter's size and metal area, and enables continuous phase control by controlling the varying lengths of the delay line.

[0048] Figure 4 The reflection coefficient from normal main polarization to main polarization at six different delay line lengths in the range of 42GHz to 52GHz is demonstrated. In the range of 43GHz to 51GHz, the unit reflection coefficient mostly fluctuates between -2 and -3dB, and the relative bandwidth can reach 17%.

[0049] Figure 5 The reflection coefficients of the six types of units with main polarization incident on cross-polarization are shown in the range of 42GHz to 52GHz. In the range of 43GHz to 51GHz, most of the unit cross-polarizations are below -30dB, with good polarization purity.

[0050] Figure 6 The normal reflection phase curves of the above six types of units at different delay line lengths in the range of 42GHz to 52GHz are shown. In the range of 43GHz to 51GHz, by changing the delay line length, the unit reflection phase can cover 0° to 360°.

[0051] Figure 7 The main polarization-to-main polarization reflection coefficients of the six types of units mentioned above are shown at a 40° elevation angle of incidence in the 42GHz to 52GHz range. The unit reflection coefficients can still be maintained at -2 to -4dB in the 43GHz to 47GHz range.

[0052] Figure 8 The cross-polarization reflection coefficients of the six types of units mentioned above are shown at a 40° elevation angle of incidence in the 42GHz to 52GHz range. In the 43GHz to 47GHz range, the cross-polarization reflection coefficients of the units are mostly below -20dB.

[0053] Figure 9 Demonstrates the main polarization beam of the reflective antenna array at 46GHz Scanning pattern of θ=0°~50°: the array gain drops from 27.2dBi to 22.3dBi within the scanning range of θ=0°~50°, the maximum sidelobe is less than -17dB, and the aperture efficiency is 35%.

[0054] It should be noted that the slot structure in the present invention is not limited to an I-shaped structure; other slot-coupled feed structures are also possible. In summary, the present invention proposes an optically transparent linearly polarized millimeter-wave reflectarray antenna based on a low-loss dielectric substrate. This reflectarray antenna utilizes a fully planar structure with a low profile and simple structure. While achieving phase modulation of the incident wave, it also exhibits good optical transparency. It has a wide range of applications in satellite communications, building curtain walls, vehicle-mounted platforms, and other fields.

[0055] Compared with the prior art, due to the adoption of the above technical solution, the present invention provides a fully planar, low-profile, linearly polarized modified cycloolefin polymer-based reflectarray antenna with good optical transparency, which has the following advantages:

[0056] (1) The proposed reflectarray antenna uses a medium with good transparency and adopts a transparent metal grid instead of opaque metal to achieve optical transparency of the reflectarray antenna. The triangular periodic array arrangement can reduce the number of elements under the same array aperture, further reducing the metal area of ​​the reflectarray and improving the overall optical transparency of the array.

[0057] (2) The proposed reflector array antenna adopts a fully planar design with a simple structure and is easy to integrate. Different metal structures are all connected through electromagnetic field coupling, which is conducive to actual processing and reduces the problem of reduced transparency caused by metal vias. It has the advantage of a low profile. The reflector array profile is only 0.17λ~0.2λ, where λ is the free space wavelength.

[0058] (3) The proposed reflectarray antenna adopts a laminated patch radiation structure, which can effectively reduce the dielectric stacking structure and increase the radiation bandwidth. It adopts a unique gridded out-of-plane Marchand balun structure, which can effectively realize the common mode conversion to differential mode to reduce the loss caused by the modified cycloolefin polymer;

[0059] (4) The gridded open-circuit out-of-plane differential time delay line phase shifter used uses open-circuit reflection to form a double time delay to reduce the volume of the phase shifter and the metal area. It can improve the transmittance while achieving continuous phase modulation to meet different phase requirements, and can significantly reduce the loss caused by the phase control quantization error.

[0060] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or N embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples without contradiction.

[0061] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Thus, a feature specified as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "N" means at least two, such as two, three, etc., unless otherwise specifically defined.

Claims

1. An optically transparent linearly polarized millimeter wave reflector array based on a low-loss dielectric substrate, characterized in that: The invention comprises a feed source and a light-transparent reflective array, wherein the reflective array antenna units are arranged in a triangular periodic array on the light-transparent reflective array at the vertices of a regular triangle grid, the diameter of the light-transparent reflective array is D, and the vertical distance from the feed source to the reflective array antenna units is F, wherein 0.6≤F / D≤1.

5.

2. The optically transparent linearly polarized millimeter wave reflectarray based on a low-loss dielectric substrate according to claim 1, characterized in that: The side length of the equilateral triangle grid is 0.3 to 0.4 wavelengths of electromagnetic waves in free space.

3. The optically transparent linearly polarized millimeter wave reflectarray based on a low-loss dielectric substrate according to claim 1, characterized in that: The reflectarray antenna unit has a stacked structure, including metal layers and dielectric layers, totaling eighteen layers, including five metal layers, six OCA adhesive layers, and seven dielectric layers, wherein the seven dielectric layers include four polyethylene terephthalate films and three modified cycloolefin polymer films; the eighteen layers, from top to bottom, are respectively the first metal layer, the first polyethylene terephthalate layer, the first OCA adhesive layer, the second polyethylene terephthalate layer, the second metal layer, the second OCA adhesive layer, the third polyethylene terephthalate layer, the third OCA adhesive layer, the first modified cycloolefin polymer layer, the fourth OCA adhesive layer, the fourth polyethylene terephthalate layer, the third metal layer, the fifth OCA adhesive layer, the second modified cycloolefin polymer layer, the fourth metal layer, the sixth OCA adhesive layer, the fifth metal layer, and the third modified cycloolefin polymer layer; The reflectarray antenna unit is divided into a radiation layer, a slot-coupled feeding layer, and a phase-shifting layer. From top to bottom, the 1st to 11th layers are radiation layers, the 12th layer is a slot-coupled feeding layer, and the 13th to 18th layers are phase-shifting layers.

4. The optically transparent linearly polarized millimeter wave reflectarray based on a low-loss dielectric substrate according to claim 1, characterized in that: The overall thickness of the optically transparent reflective front is 0.17 to 0.2λ0, where λ0 is the free space wavelength.

5. The optically transparent linearly polarized millimeter wave reflectarray based on a low-loss dielectric substrate according to claim 4, characterized in that: The first and second metal layers correspond to a metal grid line width w1 of 5μm to 20μm and a spacing l1 of 50μm to 300μm. The fourth and fifth metal layers correspond to a metal grid line width w1 and a spacing l1. The third metal layer has a metal grid line width w1 and a spacing l1. The metal grid is ±45 degrees to the edge of the structure.

6. The optically transparent linearly polarized millimeter wave reflectarray based on a low-loss dielectric substrate according to claim 3, characterized in that: The first metal layer includes an upper gridded metal rectangular stacked patch, the second metal layer includes a lower gridded metal rectangular stacked patch, the third metal layer corresponds to a gridded metal ground, the fourth metal layer includes a gradient microstrip line matching branch, a section of gridded gradient microstrip line, the upper portion of a gridded out-of-plane Marchand balun, and the upper portion of a gridded open-circuit out-of-plane differential delay line phase shifter, and the fifth metal layer includes a lower portion of a gridded out-of-plane Marchand balun and a lower portion of a gridded open-circuit out-of-plane differential delay line phase shifter.

7. The optically transparent linearly polarized millimeter wave reflectarray based on a low-loss dielectric substrate according to claim 6, characterized in that: The metal structure of the reflectarray antenna unit includes an upper gridded metal rectangular patch, a lower gridded metal rectangular patch, a partial ground grid with a line width of w1 and a spacing of l1, a projection grid of the upper gridded metal patch with a line width of w1 and a spacing of l1 on the third metal layer, a projection grid of the lower gridded metal patch with a line width of w1 and a spacing of l1 on the third metal layer, a gridded open-circuit out-of-plane differential time delay line phase shifter with a line width of w1 and a spacing of l1 on the third metal layer, and a gridded out-of-plane Marchand balun with a line width of w1 and a spacing of l1 on the third metal layer. The projected grid of the metal layer, the projected grid of the gridded gradient microstrip line with a line width of w1 and a spacing of l1 on the third metal layer, the projected grid of the gradient microstrip line matching branches on the third metal layer, "I"-shaped gaps, gradient microstrip line matching branches, gridded gradient microstrip line with a line width of w1 and a spacing of l1, gridded out-of-plane Marchand balun with a line width of w1 and a spacing of l1, and gridded open-circuit out-of-plane differential delay line phase shifter with a line width of w1 and a spacing of l1, wherein the line width w1 is 5μm to 20μm and the spacing l1 is 50μm to 300μm.

8. The optically transparent linearly polarized millimeter wave reflectarray based on a low-loss dielectric substrate according to claim 7, characterized in that: The metal layer is etched on the polyethylene terephthalate film and the modified cycloolefin polymer substrate, the upper grid metal rectangular patch is etched on the upper surface of the first polyethylene terephthalate layer, the lower grid metal rectangular patch is etched on the lower surface of the second polyethylene terephthalate layer, the grid metal ground is etched on the lower surface of the fourth polyethylene terephthalate layer, the grid gradient microstrip line is etched on the lower surface of the second modified cycloolefin polymer layer, the grid out-of-plane Marchand balun single line to differential delay line structure is etched on the lower surface of the second modified cycloolefin polymer layer and the upper surface of the third modified cycloolefin polymer layer, and the grid open circuit out-of-plane differential delay line phase shifter structure is also etched on the lower surface of the second modified cycloolefin polymer layer and the upper surface of the third modified cycloolefin polymer layer.

9. The optically transparent linearly polarized millimeter wave reflectarray based on a low-loss dielectric substrate according to claim 7 or 8, characterized in that: The gridded out-of-plane Marchand balun consists of a gridded microstrip line, a pair of gridded open-circuited out-of-plane bent microstrip line branches with the same width as the microstrip line, and a gridded open-circuited out-of-plane differential delay line connected in parallel with the branches. The gridded microstrip line and the gridded open-circuited bent microstrip line are coupled through a narrow slot, and there is no electrical connection between the three metal structures.

10. The optically transparent linearly polarized millimeter wave reflectarray based on a low-loss dielectric substrate according to claim 7 or 8, characterized in that: The gridded gradient microstrip line and the gridded out-of-plane Marchand balun in the fourth metal layer and the fifth metal layer are electrically connected by metal, and the gridded out-of-plane Marchand balun and the gridded open-circuit out-of-plane differential delay line phase shifter are electrically connected by metal. The length of the gridded open-circuit out-of-plane differential delay line is changed to continuously change the reflection phase provided by the unit.

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