Optically transparent linearly polarized millimeter wave reflectarray based on low-loss dielectric substrate

Abstract

The application discloses a light-transparent linear polarization millimeter wave reflectarray based on a low-loss dielectric substrate and belongs to the field of wireless communication system electronic devices. The reflectarray antenna unit adopts a two-dimensional triangular periodic arrangement, and the array sparsification and sidelobe suppression requirements are considered. The application adopts a metal grid with reduced metal area and full-transparent dielectric material to improve the light transparency of the antenna. While the electromagnetic performance is ensured, the antenna transparency is improved. In the design process, full-planarization design is adopted, all metal structures transfer energy through electromagnetic coupling, the processing complexity is effectively reduced, and problems such as transparency reduction caused by metal via holes are avoided. The light-transparent reflectarray antenna has good transparency and is easy to integrate, and has a wide application prospect in the field of satellite communication.

Description

Technical Field

[0001] This invention relates to the field of electronic devices for wireless communication systems, and in particular to a light-transparent linearly polarized millimeter-wave reflective array based on a low-loss dielectric substrate. Background Technology

[0002] With the rapid development of 5G / 6G and satellite communication technologies, high-frequency millimeter-wave spectrum resources have become the core carrier supporting ultra-high-speed communication. 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 path, which involves deploying phased array antenna systems on a large scale in base stations, satellite terminals, and mobile devices to construct intelligent reflective surfaces (RIS) to enhance signal diffraction capabilities. In this context, traditional metal antennas reveal irreconcilable contradictions: on the one hand, scenarios such as building facades and vehicle platforms place rigid demands on antennas for "visual invisibility" and spatial integration, as the high reflectivity of metal structures not only damages architectural aesthetics but also generates electromagnetic interference; on the other hand, satellite terminals need to integrate large-scale arrays of thousands of elements within a limited area, and the size of metal antennas severely restricts deployment flexibility. This has driven revolutionary innovations in optically transparent electronic devices, which, by integrating high-frequency millimeter-wave communication with transparent electronic processes, resolve the contradiction between integration and functionality in traditional antennas and are core components of future intelligent surfaces and communication networks.

[0003] Based on reported literature, there are currently no Q / V band optically transparent reflective array antennas. Reflective array antennas, benefiting from their planar structure, ease of fabrication, and lack of complex feed networks, often achieve large array sizes and high gains. Existing reflective array antennas evolved from traditional curved metal reflective array antennas, achieving different beamformations through phase modulation and reflection of the feed's transmitted energy. Existing optically transparent reflective array antennas are often evolved from reflective array antennas by making them more transparent. Commonly used transparent antennas typically employ transparent materials such as meshed metals, transparent conductive materials, and transparent dielectrics to achieve optical transparency. Phase modulation methods for optically transparent reflective array antennas are mainly divided into two categories: the first category achieves discrete phase modulation through resonant structures, such as transparent resonant metal rings, using specific resonant modes and multi-layer cascading to achieve phase modulation; the second category achieves continuous phase modulation through phase shifter structures, such as time delay lines, where different lengths of time delay lines can control different phase states. Compared to the first type of implementation, the second type offers greater bandwidth, fewer stacked structures, and higher transparency, but also requires more unit space to house the phase shifters. Summary of the Invention

[0004] This invention provides an optically transparent linearly polarized millimeter-wave reflector array based on a low-loss dielectric substrate. It adopts a fully planar structure with a low profile and simple structure. It achieves phase modulation of the incident wave while having good optical transparency, and has broad application prospects in the field of satellite communication.

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

[0006] Optionally, in one embodiment of the present invention, the side length of the equilateral triangular mesh is 0.3 to 0.4 times the wavelength of electromagnetic waves in free space.

[0007] Optionally, in one embodiment of the present invention, the reflector antenna element is a stacked structure, comprising a total of eighteen layers including metal layers and dielectric layers, including five metal layers, six OCA adhesive layers, and seven dielectric layers. The seven dielectric layers include four polyethylene terephthalate (PET) films and three modified cyclic olefin polymer (MORP) films. The eighteen layers, from top to bottom, are: a first metal layer, a first PET layer, a first OCA adhesive layer, a second PET layer, a second metal layer, a second OCA adhesive layer, a third PET layer, a third OCA adhesive layer, a first modified cyclic olefin polymer (MORP) layer, a fourth OCA adhesive layer, a fourth PET layer, a third metal layer, a fifth OCA adhesive layer, a second modified cyclic olefin polymer (MORP) layer, a fourth metal layer, a sixth OCA adhesive layer, a fifth metal layer, and a third modified cyclic olefin polymer (MORP) layer.

[0008] The reflective array antenna element is divided into a radiating layer, a slot-coupled feed layer, and a phase-shifting layer. From top to bottom, layers 1 to 11 are radiating layers, layer 12 is a slot-coupled feed layer, and layers 13 to 18 are phase-shifting layers.

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

[0010] Optionally, in one embodiment of the present invention, the metal mesh line width w1 of the first metal layer and the second metal layer is 5μm to 20μm and the spacing l1 is 50μm to 300μm, the metal mesh line width w1 of the fourth metal layer and the spacing l1 of the fifth metal layer are the same, the metal mesh line width w1 of the third metal layer is l1 and the spacing is l1, and the metal mesh is at ±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 layer, the fourth metal layer includes a gradient microstrip line matching stub, 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 reflector array antenna element includes an upper gridded metal rectangular patch, a lower gridded metal rectangular patch, a partially grounded grid with linewidth w1 and spacing l1, a projection grid of the upper gridded metal patch with linewidth w1 and spacing l1 onto a third metal layer, a projection grid of the lower gridded metal patch with linewidth w1 and spacing l1 onto a third metal layer, a projection grid of the gridded open-circuit differential delay line phase shifter with linewidth w1 and spacing l1 onto a third metal layer, and a gridded out-of-plane Marcha The projection grid of the nd balun on the third metal layer, the projection grid of the gridded gradient microstrip line with linewidth w1 and spacing l1 on the third metal layer, the projection grid of the gradient microstrip line matching stub on the third metal layer, the "I"-shaped gap, the gradient microstrip line matching stub, the gridded gradient microstrip line with linewidth w1 and spacing l1, the gridded out-of-plane Marchand balun with linewidth w1 and spacing l1, and the gridded open-circuit out-of-plane differential delay line phase shifter with linewidth w1 and spacing l1, wherein the linewidth w1 is 5μm to 20μm and the spacing l1 is 50μm to 300μm.

[0013] Optionally, in one embodiment of the present invention, a metal layer is etched on a polyethylene terephthalate film and a modified cyclic olefin 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 layer 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 cyclic olefin 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 cyclic olefin polymer layer and the upper surface of the third modified cyclic olefin 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 cyclic olefin polymer layer and the upper surface of the third modified cyclic olefin polymer layer.

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

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

[0016] This invention relates to an optically transparent linearly polarized millimeter-wave reflector array based on a low-loss dielectric substrate. By employing a metal mesh with reduced metal area and a fully transparent dielectric material, the antenna's optical transparency is improved, enhancing both electromagnetic performance and transparency. The design utilizes a fully planar approach, with all metal structures transferring energy via electromagnetic coupling, effectively reducing manufacturing complexity and avoiding issues such as reduced transparency caused by metal vias. This optically transparent reflector array antenna exhibits good transparency and ease of integration, making it promising for broad applications in satellite communications.

[0017] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[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 taken in conjunction with the accompanying drawings, wherein:

[0019] Figure 1 This is 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 This is a schematic diagram of the stacked structure of the linearly polarized optically transparent reflective antenna array unit based on the modified cyclic olefin polymer in Example 1.

[0021] Wherein, 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 cyclic olefin polymer layer, 11 is the fourth polyethylene terephthalate layer, 12 is the third metal layer, 14 is the second modified cyclic olefin polymer layer, 15 is the fourth metal layer, 17 is the fifth metal layer, and 18 is the third modified cyclic olefin polymer layer;

[0022] Figure 3 This is a schematic diagram of each metal layer of the linearly polarized optically transparent reflective antenna array unit based on modified cyclic olefin polymer in Example 1.

[0023] Among them, 1a is a meshed metal patch with a linewidth of w1 and a grid spacing of l1 in the upper layer; 5a is a meshed metal patch with a linewidth of w1 and a grid spacing of l1 in the second layer; 12a is a partially meshed patch with a linewidth of w1 and a grid spacing of l1; 12b is the projected grid of the meshed metal patch with a linewidth of w1 and a grid spacing of l1 in the upper layer on the third metal layer; 12c is the projected grid of the meshed metal patch with a linewidth of w1 and a grid spacing of l1 in the lower layer on the third metal layer; 12d is the projected grid of the meshed open-circuit differential delay line phase shifter with a linewidth of w1 and a grid spacing of l1 on the third metal layer; and 12e is a mesh with a linewidth of w1 and a grid spacing of l1. The gridded surface of the Marchand balun is projected onto the third metal layer. 12f is the projection grid of the gridded gradient microstrip line with linewidth w1 and grid spacing l1 onto the third metal layer. 12g is the projection grid of the gradient microstrip line matching stub onto the third metal layer. 12h is the "I"-shaped slot. 15a is the gradient microstrip line matching stub. 15b is the gridded gradient microstrip line with linewidth w1 and grid spacing l1. 15c and 17a are the gridded surface of the Marchand balun with linewidth w1 and grid spacing l1. 15d and 17b are the gridded open-circuit surface differential delay line phase shifters with linewidth w1 and grid spacing l1.

[0024] Figure 4 The curves of the reflection coefficient from main polarization to main polarization as a function of frequency are given for the linearly polarized optically transparent reflective antenna array element based on modified cyclic olefin polymer in the range of 42 GHz to 52 GHz in Example 1 when the element is incident normally at different types of delay line lengths.

[0025] Figure 5 The curves of the reflection coefficient of the modified cyclic olefin polymer-based linearly polarized optically transparent reflective antenna array element in the range of 42 GHz to 52 GHz in Example 1 as a function of frequency under different types of time delay line lengths when the element is incident normally.

[0026] Figure 6The curves of the reflection phase from main polarization to main polarization as a function of frequency are given for the linearly polarized optically transparent reflective antenna array element based on modified cyclic olefin polymer in the range of 42 GHz to 52 GHz in Example 1 when the element is incident normally, under different types of time delay line lengths.

[0027] Figure 7 The curves of the reflection coefficient from main polarization to main polarization as a function of frequency for the linearly polarized optically transparent reflective antenna array element based on modified cyclic olefin polymer in the range of 42 GHz to 52 GHz in Example 1 are given when it is incident at an elevation angle of 40° for different types of delay line lengths.

[0028] Figure 8 The reflection coefficient curves of the modified cyclic olefin polymer-based linearly polarized optically transparent reflective antenna array element in Example 1, when incident at a 40° elevation angle along different types of delay line lengths, are given as a function of frequency from main polarization to cross polarization.

[0029] Figure 9 The main polarization beam scanning pattern of the linearly polarized optically transparent reflective antenna array based on modified cyclic olefin polymers at 46 GHz in Example 1 is given. Detailed Implementation

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

[0031] Figure 1 This is 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.

[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 (I) and an optically transparent reflector array (II). The reflector array antenna elements are arranged in a triangular periodic array on the optically transparent reflector array (II) at the vertices of an equilateral triangular grid. The side length of the equilateral triangular grid is 0.3 to 0.4 wavelengths of electromagnetic waves in free space. The diameter of the optically transparent reflector array is D, which is 64 mm in the embodiment. The vertical distance from the feed to the reflector array antenna element is F, where 0.6 ≤ F / D ≤ 1.5, which is 1.3 in the embodiment.

[0033] like Figure 2As shown, the reflective array antenna element comprises 18 layers in total, including metal and dielectric layers. These can be broadly categorized into a radiating layer, a slot-coupled feed layer, and a phase-shifting layer. The 18 layers include 5 metal layers (from top to bottom: first metal layer (1), second metal layer (5), third metal layer (12), fourth metal layer (15), fifth metal layer (17), 6 OCA bonding layers (3, 6, 8, 10, 13, 16), and 7 dielectric layers. The dielectric layers consist of four polyethylene terephthalate films and three modified cyclic olefin polymer films (from top to bottom: first polyethylene terephthalate film, second metal layer, third metal layer, fourth metal layer, fifth metal layer, and fifth ... The array consists of an ester layer (2), a second polyethylene terephthalate layer (4), a third polyethylene terephthalate layer (7), a first modified cyclic olefin polymer layer (9), a fourth polyethylene terephthalate layer (11), a second modified cyclic olefin polymer layer (14), and a third modified cyclic olefin polymer layer (18). Layers 1 to 11 form a radiating layer, layer 12 is a slot-coupled feeding layer, and layers 13 to 18 form a phase-shifting layer. The overall thickness of the optically transparent reflective array is 0.17–0.2λ0, where λ0 is the free-space wavelength. In this embodiment, the overall thickness of the unit is 1.03 mm.

[0034] Specifically, a metal layer is etched on a polyethylene terephthalate (PET) film and a modified cyclic olefin polymer (COP) substrate. An upper gridded metal rectangular patch is etched on the upper surface of the first PET layer, a lower gridded metal rectangular patch is etched on the lower surface of the second PET layer, a gridded metal layer is etched on the lower surface of the fourth PET layer, a gridded gradient microstrip line is etched on the lower surface of the second COP layer, a gridded out-of-plane Marchand balun single-line to differential delay line structure is etched on the lower surface of the second COP layer and the upper surface of the third COP 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 COP layer and the upper surface of the third COP layer.

[0035] The first and fifth layers have a metal mesh line width w1 (5μm~20μm) and a spacing l1 (50μm~300μm). The 15th and 17th layers have a metal mesh line width w1 and a spacing l1. The 12th layer has a metal mesh line width w1 and a spacing l1. The metal mesh is at ±45 degrees to the edge of the structure.

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

[0037] The unit metal structure includes an upper gridded metal rectangular laminated patch (1a), a lower gridded metal rectangular laminated patch (5a), a partially grounded grid (12a) with a linewidth of 5μm to 20μm and a spacing of 50μm to 300μm, and a projected grid (12b) of the upper gridded metal patch with a linewidth w1 (5μm to 20μm) and a spacing l1 (50μm to 300μm) on the third metal layer. The projection grid (12c) of the lower-layer gridded metal patches with linewidth w1 (5μm~300μm) and spacing l1 (50μm~300μm) on the third metal layer; the projection grid (12d) of the gridded open-circuit differential delay line phase shifter with linewidth w1 (5μm~20μm) and spacing l1 (50μm~300μm) on the third metal layer; and the gridded non-circuit Ma... The projection grid of the rchand balun on the third metal layer (12e), the projection grid of the gridded gradient microstrip line with linewidth w1 (5μm~20μm) and spacing l1 (50μm~300μm) on the third metal layer (12f), the projection grid of the gradient microstrip line matching stub on the third metal layer (12g), the "I"-shaped gap (12h), the gradient microstrip line matching stub (15a), with linewidth w1 (5μm~20μm) and spacing l1 (50μm~300μm) on the third metal layer. Meshable gradient microstrip lines with linewidth w1 (5μm~300μm) and spacing l1 (50μm~300μm) (15b), meshable non-surface Marchand baluns with linewidth w1 (5μm~20μm) and spacing l1 (50μm~300μm) (15c and 17a), and meshable open-circuit non-surface differential delay line phase shifters with linewidth w1 (5μm~20μm) and spacing l1 (50μm~300μm) (15d and 17b).

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

[0039] Specifically, the gridded metal ground in the third metal layer includes a partial grid (12a) with a linewidth of 5μm to 20μm and a spacing of 50μm to 300μm, an upper gridded metal patch with a linewidth w1 (5μm to 20μm) and a spacing l1 (50μm to 300μm) projected onto the third metal layer as a grid (12b), a lower gridded metal patch with a linewidth w1 (5μm to 20μm) and a spacing l1 (50μm to 300μm) projected onto the third metal layer as a grid (12c), and a lower gridded metal patch with a linewidth w1 (5μm to 20μm) and a spacing l1 (50μm to 300μm) projected onto the third metal layer as a grid (12c). The projection grid of the gridded open-circuit differential delay line phase shifter (12d) on the third metal layer, the projection grid of the gridded Marchand balun with linewidth w1 (5μm~20μm) and spacing l1 (50μm~300μm) on the third metal layer (12e), the projection grid of the gridded gradient microstrip line with linewidth w1 (5μm~20μm) and spacing l1 (50μm~300μm) on the third metal layer (12f), the projection grid of the gradient microstrip line matching stub on the third metal layer (12g), and the "I" shaped gap (12h).

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

[0041] Specifically, in the fourth and fifth metal layers, there is a metal electrical connection between the gridded gradient microstrip line and the gridded out-of-plane Marchand balun, and a metal electrical connection between the gridded out-of-plane Marchand balun and the gridded open-circuit out-of-plane differential delay line phase shifter. Changing the length of the gridded open-circuit out-of-plane differential delay line can continuously change the reflection phase provided by the cell.

[0042] Employing a unique eccentric Marchand balun structure, the common-mode to differential-mode conversion function can be effectively realized to reduce the loss caused by the modified cyclic olefin polymer. The reflective array antenna uses an open-circuit eccentric differential time delay line phase shifter, which forms twice the time delay through open-circuit reflection, significantly reducing the phase shifter volume and metal area. Furthermore, continuous phase control is achieved by controlling the different lengths of the time delay line.

[0043] This invention discloses a modified cyclic olefin polymer baseline-polarized optically transparent reflective array antenna operating at 43 GHz to 51 GHz. The antenna elements employ a two-dimensional triangular periodic arrangement, balancing array sparsity with sidelobe suppression requirements. The proposed antenna element consists of stacked patches, coupling slots, a misaligned Marchand balun, and an open-circuit misaligned time delay line phase shifter; varying the time delay line length allows for phase control of the element. This invention utilizes a metal mesh with reduced metal area and a fully transparent dielectric material to improve the antenna's optical transparency, enhancing both electromagnetic performance and transparency. The design employs a fully planar approach, with all metal structures transferring energy via electromagnetic coupling, effectively reducing manufacturing complexity and avoiding transparency degradation caused by metal vias. This optically transparent reflective array antenna exhibits good transparency and ease of integration, showing broad application prospects in satellite communications.

[0044] The following detailed description of the optically transparent linearly polarized millimeter-wave reflector array based on a low-loss dielectric substrate of the present invention will be provided through a specific embodiment.

[0045] Example 1

[0046] like Figure 1 As shown, this invention proposes a modified cyclic olefin polymer baseline-polarized optically transparent reflective array antenna, which includes a linearly polarized feed I and an optically transparent reflective array II. The diameter of the optically transparent reflective array II is D, which is 64 mm in this embodiment. The vertical distance from the feed to the array is F, and the value of F / D is between 0.6 and 1.5, which is 1.3 in this embodiment. The reflective array elements cover 43 GHz to 51 GHz, and its structure is fully planar, with a low profile and good optical transparency. The elements are arranged periodically according to equilateral triangles and placed on the vertices of equilateral triangles. The side length of the equilateral triangles is between 0.3λ and 0.4λ, where λ is the free space wavelength, which is 2.18 mm in this embodiment.

[0047] Detailed diagrams of each layer of metal structure are shown below. Figure 3As shown, the grid linewidth in the first and second metal layers is w1 (5μm~20μm) and the grid spacing is l1 (50μm~300μm). The grid linewidth in the fourth and fifth metal layers is w1 and the grid spacing is l1. The third metal layer contains both a grid linewidth of w1 and a grid spacing of l1. The metal grid is at ±45 degrees to the edge of the structure. In the embodiment, the metal grids corresponding to the first metal layer 1 and the second metal layer 5 have a linewidth of 10μm and a spacing of 100μm. The metal grids corresponding to the fourth metal layer 15 and the fifth metal layer 17 have a linewidth of 10μm and a spacing of 100μm. The metal grids of the fifth metal layer 12 have a linewidth of 10μm and a spacing of 100μm. The first metal layer includes an upper patch 1a, and the second metal layer includes a lower patch 5a. The third metal layer includes a ground grid 12a with a linewidth of 10 μm and a spacing of 100 μm, a projection grid 12b of the upper gridded metal patches with a linewidth of 10 μm and a spacing of 100 μm on the third metal layer, a projection grid 12c of the lower gridded metal patches with a linewidth of 10 μm and a spacing of 100 μm on the third metal layer, a projection grid 12d of the gridded open-circuit differential delay line phase shifter with a linewidth of 10 μm and a spacing of 100 μm on the third metal layer, a projection grid 12e of the gridded out-of-plane Marchand balun with a linewidth of 10 μm and a spacing of 100 μm on the third metal layer, and a gridded gradient microstrip line with a linewidth of 10 μm and a spacing of 100 μm on the third metal layer. The fourth metal layer includes a projected grid 12f of the metal layer, a projected grid 12g of the gradient microstrip line matching stubs on the third metal layer, and an "I"-shaped gap 12h; the fourth metal layer includes a gradient microstrip line matching stub 15a, a gridded gradient microstrip line 15b with a linewidth of 10μm and a spacing of 100μm, a gridded out-of-plane Marchand balun upper portion 15c with a linewidth of 10μm and a spacing of 100μm, and a gridded open-circuit out-of-plane differential delay line phase shifter upper portion 15d with a linewidth of 10μm and a spacing of 100μm; the fifth metal layer includes a gridded out-of-plane Marchand balun lower portion 17a with a linewidth of 10μm and a spacing of 100μm, and a gridded open-circuit out-of-plane differential delay line phase shifter lower portion 17b with a linewidth of 10μm and a spacing of 100μm. In this invention, during actual operation of the unit, the gridded multilayer patch receives electromagnetic waves radiated from space and transmits these waves through coupling gaps to the gridded graded microstrip line. The matching stubs of the graded microstrip line regulate the matching, maximizing the transmission of electromagnetic waves to the gridded graded microstrip line. In this invention, the final linewidth of the gridded graded microstrip line is consistent with the linewidth of the input end of the gridded out-of-plane Marchand balun. The electromagnetic wave propagates from the gridded graded microstrip line until it reaches the gridded out-of-plane Marchand balun, where it is then maximally converted from microstrip mode to differential mode.This invention employs a gridded open-circuit differential time-delay line phase shifter. Electromagnetic waves propagate continuously along the time-delay line, with their phase constantly changing according to the differential transmission line mode until an open-circuit reflection at the end returns along the original time-delay line, resulting in a double time delay before final radiation. This gridded open-circuit differential time-delay line phase shifter significantly reduces the phase shifter's volume and metal area, and achieves continuous phase control through the control of different time-delay line lengths.

[0048] Figure 4 The reflection coefficients of the normal main polarization to the main polarization are shown for six different delay line lengths in the range of 42 GHz to 52 GHz. In the range of 43 GHz to 51 GHz, the unit reflection coefficients mostly fluctuate between -2 and -3 dB, with a relative bandwidth of up to 17%.

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

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

[0051] Figure 7 The study demonstrates the main polarization-to-main polarization reflection coefficients of the six types of cells when incident at an elevation angle of 40° within the 42GHz to 52GHz range. The cell reflection coefficients remain between -2 and -4dB within the 43GHz to 47GHz range.

[0052] Figure 8 The reflection coefficients from main polarization to cross-polarization of the six cell types mentioned above are shown when incident at an elevation angle of 40° in the range of 42 GHz to 52 GHz. In the range of 43 GHz to 47 GHz, the cross-polarization of most cells is below -20 dB.

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

[0054] It should be noted that the slot structure in this invention is not limited to the "I" shape, but can also be other shapes of slot-coupled feeding structures. In summary, this invention proposes an optically transparent linearly polarized millimeter-wave reflective array antenna based on a low-loss dielectric substrate. This reflective array antenna adopts a fully planar structure with a low profile and simple structure. It achieves phase modulation of the incident wave while exhibiting good optical transparency, and has wide application scenarios in satellite communication, building curtain walls, vehicle platforms, and other fields.

[0055] Compared with existing technologies, this invention provides a linearly polarized modified cyclic olefin polymer-based reflective array antenna with a fully planar shape, low profile, and good optical transparency due to the adoption of the above technical solution. Its advantages are:

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

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

[0058] (3) The proposed reflective array antenna adopts a stacked patch radiation structure, which can effectively reduce the dielectric stacked structure and increase the radiation bandwidth. It adopts a unique gridded eccentric Marchand balun structure, which can effectively realize common mode conversion to differential mode to reduce the loss caused by modified cyclic olefin polymer.

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

[0060] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

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

Claims

1. A light-transparent linearly polarized millimeter-wave reflective array based on a low-loss dielectric substrate, characterized in that, The device includes a feed and an optically transparent reflective array. The reflective array antenna elements are arranged in a triangular periodic array on the optically transparent reflective array at the vertices of an equilateral triangular grid. The diameter of the optically transparent reflective array is D, and the vertical distance from the feed to the reflective array antenna elements is F, where 0.6 ≤ F / D ≤ 1.

5. The reflective array antenna element has a stacked structure, comprising a total of eighteen layers, including metal layers and dielectric layers. It includes five metal layers, six OCA adhesive layers, and seven dielectric layers. The seven dielectric layers consist of four polyethylene terephthalate (PET) films and three modified cyclic olefin polymer (CORP) films. The eighteen layers, from top to bottom, are: the first metal layer, the first PET layer, the first OCA adhesive layer, the second PET layer, the second metal layer, the second OCA adhesive layer, the third PET layer, the third OCA adhesive layer, the first modified cyclic olefin polymer (CORP) layer, the fourth OCA adhesive layer, the fourth PET layer, the third metal layer, the fifth OCA adhesive layer, the second modified cyclic olefin polymer (CORP) layer, the fourth metal layer, the sixth OCA adhesive layer, the fifth metal layer, and the third modified cyclic olefin polymer (CORP) layer. The reflective array antenna element is divided into a radiating layer, a slot-coupled feed layer, and a phase-shifting layer. From top to bottom, layers 1 to 11 are radiating layers, layer 12 is a slot-coupled feed layer, and layers 13 to 18 are phase-shifting layers. 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 layer; the fourth metal layer includes a gradient microstrip line matching stub, a section of gridded gradient microstrip line, the upper part of a gridded out-of-plane Marchand balun, and the upper part of a gridded open-circuit out-of-plane differential delay line phase shifter; the fifth metal layer includes the lower part of a gridded out-of-plane Marchand balun and the lower part of a gridded open-circuit out-of-plane differential delay line phase shifter.

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

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

4. The optically transparent linearly polarized millimeter-wave reflective array based on a low-loss dielectric substrate according to claim 3, characterized in that, The corresponding metal grid line width w1 of the first and second metal layers is 5. ~20 The spacing l1 is 50. ~300 The fourth and fifth metal layers have a metal grid line width w1 and a spacing l1, while the third metal layer has a metal grid line width w1 and a spacing l1. The metal grid is at ±45 degrees to the edge of the structure.

5. The optically transparent linearly polarized millimeter-wave reflective array based on a low-loss dielectric substrate according to claim 1, characterized in that, The metallic structure of the reflector array antenna element includes an upper gridded metal rectangular patch, a lower gridded metal rectangular patch, a partial ground grid with linewidth w1 and spacing l1, a projection grid of the upper gridded metal patch with linewidth w1 and spacing l1 onto the third metal layer, a projection grid of the lower gridded metal patch with linewidth w1 and spacing l1 onto the third metal layer, a projection grid of the gridded open-circuit differential delay line phase shifter with linewidth w1 and spacing l1 onto the third metal layer, and a gridded non-plane differential delay line phase shifter with linewidth w1 and spacing l1 onto the third metal layer. The projected grid of the Marchand balun on the third metal layer, the projected grid of the gridded gradient microstrip line with linewidth w1 and spacing l1 on the third metal layer, the projected grid of the gradient microstrip line matching stub on the third metal layer, the "I"-shaped slot, the gradient microstrip line matching stub, the gridded gradient microstrip line with linewidth w1 and spacing l1, the gridded out-of-plane Marchand balun with linewidth w1 and spacing l1, and the gridded open-circuit out-of-plane differential delay line phase shifter with linewidth w1 and spacing l1, wherein the linewidth w1 is 5 ~20 The spacing l1 is 50. ~300 .

6. The optically transparent linearly polarized millimeter-wave reflective array based on a low-loss dielectric substrate according to claim 5, characterized in that, Metal layers are etched on polyethylene terephthalate (PET) films and modified cyclic olefin polymer (PET) substrates. Upper gridded metal rectangular patches are etched on the upper surface of the first PET layer, lower gridded metal rectangular patches are etched on the lower surface of the second PET layer, gridded metal ground is etched on the lower surface of the fourth PET layer, gridded gradient microstrip lines are etched on the lower surface of the second PET layer, gridded out-of-plane Marchand balun single-line to differential delay line structure is etched on the lower surface of the second PET layer and the upper surface of the third PET layer, and gridded open-circuit out-of-plane differential delay line phase shifter structure is also etched on the lower surface of the second PET layer and the upper surface of the third PET layer.

7. The optically transparent linearly polarized millimeter-wave reflective array based on a low-loss dielectric substrate according to claim 5 or 6, characterized in that, The gridded out-of-plane Marchand balun consists of a gridded microstrip line, a pair of gridded open-circuit out-of-plane bent microstrip line stubs of the same width as the microstrip line, and a gridded open-circuit out-of-plane differential delay line connected in parallel with the stubs. The gridded microstrip line and the gridded open-circuit bent microstrip line are coupled through a narrow slot, and there is no electrical connection between the three metal structures.

8. The optically transparent linearly polarized millimeter-wave reflective array based on a low-loss dielectric substrate according to claim 5 or 6, characterized in that, In the fourth and fifth metal layers, there is a metal electrical connection between the gridded gradient microstrip line and the gridded out-of-plane Marchand balun, and a metal electrical connection between the gridded out-of-plane Marchand balun and the gridded open-circuit out-of-plane differential delay line phase shifter. Changing the length of the gridded open-circuit out-of-plane differential delay line continuously changes the reflection phase provided by the cell.

Images