Lightweight paper-based reflective lens for electromagnetic beam steering, and planar reflector antenna comprising same

Abstract

The present invention belongs to the technical field of antennas. Disclosed are a lightweight paper-based reflective lens for electromagnetic beam steering, and a planar reflector antenna comprising same. The reflective lens comprises a paper-based main body, wherein the paper-based main body is formed in such a way that a sheet-like paper substrate encloses cavity structures, which are periodically arranged at intervals, and the paper-based main body has two opposite surfaces, i.e., an upper surface and a lower surface, which are respectively a control surface and a reflective plane for electromagnetic waves; and the sheet-like paper substrate, on which thin-film symbol units made of a metal material are distributed and attached. The planar reflector antenna further comprises a feed source, wherein the feed source is close to the control surface and is mounted on the control surface in an inverted manner, and the feed source moves back and forth along a trajectory on the control surface. An electromagnetic-wave reflecting plate is provided on a surface of the reflective plane. The feed source in the present invention can be placed at any position on the control surface, and all electromagnetic waves emitted by the feed source at any position can propagate outward from the reflective lens in the form of plane waves after passing through the planar reflector antenna. Moreover, the bandwidth of wide-angle scanning realized by means of the planar reflector antenna can be up to 80%, which is much wider than that of a conventional reflector antenna.

Description

A lightweight paper-based reflective lens for electromagnetic wave beam modulation and its planar reflective antenna Technical Field

[0001] This invention belongs to the field of antenna technology, specifically relating to a lightweight paper-based reflective lens for electromagnetic wave beam modulation and its planar reflective antenna. Background Technology

[0002] With the rapid development of next-generation mobile communication technologies (B5G / 6G), there is an urgent need for antennas with large bandwidth, high gain, and wide-angle scanning. As a form of high-gain antenna, the main advantages of reflective large-aperture antennas are high gain, high efficiency, and no need for a feed network, which has attracted widespread attention from academia and industry in recent years. Currently, there are two main types of classic large-aperture reflective antennas: parabolic antennas and reflector antennas.

[0003] Traditional parabolic antennas utilize a curved surface structure to convert spherical waves at the focal point into high-gain plane waves. During transmission, the signal radiates from the feed source towards the parabolic surface, and after reflection, it radiates into the air. For example, Chinese Patent CN1152196A discloses a parabolic antenna comprising a reflector, a horn-shaped feed source, one end of which is fixed to a frame behind the reflector, and the other end of which is a cantilever arm fixing the horn-shaped feed source. A pair of hinges, a boss, and a shaft facilitate the easy placement of the horn-shaped feed source at the focal point of the reflector. As shown in Figure 1, because the feed source is located at the focal point of the parabolic surface, the electromagnetic wave, after reflection, radiates parallel to the normal of the parabolic surface.

[0004] The reflector antenna achieves phase modulation of the electromagnetic waves arriving at the surface through a resonant structure on the aperture surface, as shown in Figure 1. In the prior art, Chinese patent CN107634339B discloses a highly directional umbrella-shaped convex conformal reflector antenna based on a metasurface. This antenna includes an umbrella-shaped convex carrier, an umbrella-shaped convex mirror, a feed source, a coaxial adapter, and a support structure. The umbrella-shaped convex mirror is composed of a planar polygonal discrete metasurface with even-numbered sides (regular n-sided) and m×n planar isosceles trapezoidal discrete metasurfaces, embedded on the convex surface of the umbrella-shaped carrier. Both the planar polygonal discrete metasurface and the planar isosceles trapezoidal discrete metasurface include a dielectric substrate, a radiating ground plane, and a resonant ring metasurface. The resonant ring metasurface is composed of resonant rings of different specifications arranged in a periodic two-dimensional linear pattern, with each resonant ring providing phase compensation for the incident wave. This prior art mainly solves the problem that the convex mirror conforming to the umbrella-shaped convex carrier cannot achieve beam calibration, but due to the use of a resonant structure, the operating bandwidth of the reflector antenna will be narrowed.

[0005] Furthermore, as shown in Figure 1, both parabolic surfaces and reflectors share the same drawback: the feed source must be placed directly above the center of the parabolic / reflector. Once the feed source deviates from the focal point, the antenna gain will drop sharply, and the antenna beam scanning angle will also become smaller.

[0006] Therefore, how to achieve a wide-bandwidth, wide-angle scanning, and high-gain reflective antenna is a major technical challenge and shortcoming in this field. Summary of the Invention

[0007] To address the problems in related technologies, this invention proposes a lightweight paper-based reflective lens and its planar reflective antenna for electromagnetic wave beam modulation, overcoming the aforementioned technical issues in existing technologies. The lightweight paper-based reflective lens of this invention includes a paper-based body, which is formed by a sheet-like paper base surrounding periodically spaced hole structures. It has two opposing surfaces, an upper and a lower surface, serving as the control surface and a reflecting plane for electromagnetic waves, respectively. Thin-film metallic symbol units are distributed and attached to the sheet-like paper base. An electromagnetic wave reflector is disposed on the surface of the reflecting plane. A feed source is positioned close to and inverted on the control surface. Electromagnetic waves are reflected and propagated within the reflective lens along a curved path and collimated before exiting the reflective lens. The gain roll-off of electromagnetic waves emitted from different feed sources on the focal plane after radiation by the planar reflective antenna is less than 2 dB.

[0008] The technical solution of the present invention is implemented as follows: a lightweight paper-based reflective lens for electromagnetic wave beam modulation, comprising a paper-based body, wherein the paper-based body is formed by surrounding periodically spaced void structures with sheet-like paper base, and has two opposing surfaces, an upper and a lower surface, which are respectively the control surface of electromagnetic waves and the reflection surface.

[0009] The sheet-like paper base has distributed symbol units made of thin film-like metallic material.

[0010] Furthermore, the attachment methods of the symbol units include, but are not limited to, printing and pasting.

[0011] It should be noted that: the symbol unit being attached to the surface of the sheet-like paper base, or the symbol unit being disposed inside the sheet-like paper base, also has the same technical effect.

[0012] The symbol unit is compared with the metal surface area of ​​the symbol unit per unit volume in the paper base body. The metal surface area per unit volume in the middle of the paper base body is greater than that in the periphery of the paper base body.

[0013] The reflective plane has an electromagnetic wave reflector plate on its surface.

[0014] Furthermore, the control surface is planar and is arranged parallel to the reflecting plane;

[0015] The paper base body is cylindrical, polygonal, or frustum-shaped.

[0016] The cavity structure is a circular or polygonal three-dimensional columnar void structure.

[0017] Furthermore, at the location with the largest metal surface area per unit volume, the metal surface area gradually decreases in the radial direction toward the circumference; or, decreases in steps; or decreases periodically.

[0018] It should be noted that step reduction means that the reduction of the metal surface area is not a continuous and smooth decrease, but rather that there may be some obvious inflection points or plateaus during the decrease, causing the rate of decrease to slow down or stop near these points, thus forming a step-like shape.

[0019] Periodic decrease refers to the fact that during the process of decreasing the surface area of ​​the metal, its value exhibits a periodic downward trend. This periodic change usually means that within a certain fixed time interval, the value of the curve will undergo a complete rise and fall process, and this process will repeat, forming periodic fluctuations.

[0020] Furthermore, let n0 be the electromagnetic refractive index at the location with the largest unit volume of the metal surface area, w be the height between the upper and lower opposing surfaces of the paper substrate, and r be the radial distance extending circumferentially with n0 as the center. Then, the refractive index n(r) at position r conforms to the following inverse hyperbolic cosine distribution law:

[0021] n(r) = n0sech(πr / (4w)).

[0022] It should be noted that the larger the surface area of ​​the metal, the larger the value of n0, and the larger the final refractive index n(r); however, in practical applications, the value of n0 is generally between 1 and 3. Higher values ​​of n0 are also possible, but they would be relatively difficult to implement.

[0023] Furthermore, the symbol unit is disposed on the sidewall surrounding and facing the cavity structure, and the unit volume covers at least one cavity structure in the planar direction and contains at least one symbol unit in the vertical direction; in this invention, it means that at least one cavity structure is included in the transverse plane of the reflecting lens, and at least one symbol unit is included in the vertical plane perpendicular to the transverse plane.

[0024] At least some of the hole structures have different arrangement density, size, or shape of the symbol units compared to other hole structures; it should be noted that within the same paper substrate, the symbol units of different hole structures have different characteristics; in this invention, different equivalent dielectric constants can be obtained by adjusting the symbol units.

[0025] Furthermore, the paper base material includes aramid paper.

[0026] Furthermore, the electromagnetic wave reflector is made of metal.

[0027] Furthermore, the paper base includes, but is not limited to, being made of aramid paper or flexible PCB board, and the symbol unit is fixed to the aramid paper or flexible PCB board by printing or attaching.

[0028] Furthermore, the shape of the symbol unit includes an open ring, a cross shape, or a circular ring.

[0029] Furthermore, the equivalent dielectric constant can be changed by adjusting the side length of each side of each of the symbol units.

[0030] Furthermore, the side length is positively correlated with the equivalent dielectric constant; that is, the larger the side length, the higher the equivalent dielectric constant.

[0031] Furthermore, the equivalent dielectric constant ranges from 1 to 2.

[0032] The symbol unit is made of a highly conductive metallic material.

[0033] A planar reflective antenna for wide-angle, high-gain applications, comprising the aforementioned reflective lens; and,

[0034] The feed source is positioned close to and inverted on the control surface, which is a plane; the electromagnetic wave is reflected and propagated within the reflective lens in a curved path, and then collimated and emitted outside the reflective lens.

[0035] Furthermore, the feed source is a moving feed source, and the moving trajectory extends along a straight line or a plane and corresponds to the control surface; so that a single moving feed source can achieve the technical effect of scanning.

[0036] Alternatively, the feed source is a fixed feed source, which has multiple feed sources arranged along a straight line or plane and corresponding to the control surface; the present invention achieves the effect of multiple beams by setting multiple feed sources at the same time, with one feed source corresponding to one beam; under the condition of multiple beams, multiple electromagnetic waves at different angles will be emitted in the form of plane waves in different directions after being emitted.

[0037] Furthermore, the output surfaces of the electromagnetic waves from the multiple feed sources are located at the same height.

[0038] Furthermore, the focal plane of the reflecting lens is set to coincide with the control plane, and the feed source is mounted close to the surface of the paper-based body.

[0039] It should be noted that traditional antennas generally have only one central focal point, and the feed needs to be placed at the central focal point, extending along the central focal point and perpendicular to the optical axis to form a plane. If the feed is placed on this plane away from the central focal point, the focusing effect of the electromagnetic waves emitted by the feed will be worse. However, the entire incident plane of the reflective lens described in this invention is a focal plane. The refraction effect of the electromagnetic waves emitted by the feed at any position on the focal plane is basically the same. This invention will not cause the problem of a sharp drop in antenna gain and a smaller antenna beam scanning angle.

[0040] Moreover, in the prior art, the feed of parabolic antennas and reflector antennas must be suspended at the center focus, which is difficult to install. However, the feed of the reflector lens described in this invention is directly installed along the plane. Planar installation is simpler and more convenient than suspension installation. Therefore, compared with existing parabolic antennas and reflector antennas, the planar reflector antenna of this invention is easier to install the feed.

[0041] The gain roll-off of electromagnetic waves emitted by a feed source located at any position on the focal plane after being radiated by the reflecting lens is less than 2dB.

[0042] Furthermore, the antenna aperture surface refers to the cross-section of the planar reflective antenna, and the control surface is the antenna aperture surface that outputs electromagnetic waves.

[0043] The beneficial effects of this invention are:

[0044] This invention discloses a lightweight paper-based reflective lens and its planar reflective antenna for electromagnetic wave beam modulation. The reflective lens includes a paper-based main body, which is formed by a sheet of paper surrounding periodically spaced hole structures. It has two opposing surfaces, an upper and a lower surface, serving as the control surface and a reflecting surface for the electromagnetic waves, respectively. Thin-film metallic symbol units are distributed and attached to the sheet of paper. A feed source is positioned close to and inverted on the control surface, and the feed source reciprocates along the trajectory of the control surface. An electromagnetic wave reflector is disposed on the surface of the reflecting surface. In this invention, the feed source can be placed at any position on the control surface, and electromagnetic waves emitted by the feed source at any position can propagate as plane waves to the outside of the reflective lens after passing through the planar reflective antenna.

[0045] Moreover, compared with parabolic antennas and reflector antennas, the biggest advantage of this invention is that when the feed moves, this invention can achieve wide-angle beam scanning. Within a scanning range of ±50 degrees, the gain roll-off of the planar reflector antenna described in this invention is less than 2dB, and it can achieve very high gain and aperture efficiency. At the same time, this invention can also achieve multi-beam effect.

[0046] Furthermore, the wide-angle scanning bandwidth achieved by the planar reflector antenna of the present invention can reach 80%, which is much wider than that of traditional reflector antennas. Attached Figure Description

[0047] Figure 1 is a schematic diagram of the electromagnetic wave propagation path of existing parabolic antennas and reflector antennas;

[0048] Figure 2 is a schematic diagram showing the radial decrease in refractive index on the aperture surface of the antenna of the present invention;

[0049] Figure 3 is a schematic diagram of the electromagnetic wave propagation path when the feed source of the present invention is at different positions on the antenna aperture surface;

[0050] Figure 4 is a schematic diagram of the symbol unit printed on aramid paper according to the present invention;

[0051] Figure 5 is a top view of the planar reflective antenna of the present invention, which uses a paper-based body as a carrier;

[0052] Figure 6 is a side view of the planar reflective antenna of the present invention, which uses a paper-based body as a carrier;

[0053] Figure 7 is a three-dimensional structural diagram of the planar reflective antenna based on a reflective lens according to the present invention;

[0054] Figure 8 is a schematic diagram showing the position of the feed source of the present invention on the antenna aperture plane;

[0055] Figure 9 is a schematic diagram of the changes in antenna beam scanning angle and gain when the position of the feed source of the present invention is moved;

[0056] Figure 10 is a schematic diagram of the gain curves of the present invention at different scanning angles as a function of frequency. Detailed Implementation

[0057] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0058] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0059] Example 1

[0060] As shown in Figures 1-10, this embodiment provides a lightweight paper-based reflective lens for electromagnetic wave beam modulation, comprising a paper-based body.

[0061] The paper-based body is formed by surrounding periodically spaced void structures with sheet-like paper bases. It has two opposing surfaces, an upper surface and a lower surface, which are the control surface and the reflection surface of electromagnetic waves, respectively.

[0062] The sheet-like paper base has distributed symbol units made of thin film-like metallic material.

[0063] Specifically, the attachment methods of the symbol units include, but are not limited to, printing and pasting.

[0064] It should be noted that: the symbol unit being attached to the surface of the sheet-like paper base, or the symbol unit being disposed inside the sheet-like paper base, also has the same technical effect.

[0065] The symbol unit is compared with the metal surface area of ​​the symbol unit per unit volume in the paper base body. The metal surface area per unit volume in the middle of the paper base body is greater than that in the periphery of the paper base body; so that the refractive index of the middle position of the reflecting lens is greater than that in the periphery, as shown in Figure 2.

[0066] The reflective plane has an electromagnetic wave reflector plate on its surface.

[0067] Specifically, the control surface is a plane and is arranged parallel to the reflecting plane;

[0068] The paper base body is cylindrical, polygonal, or frustum-shaped.

[0069] It should be noted that this embodiment does not limit the shape of the paper base body. In addition to a cylindrical shape, it can also be any other three-dimensional structure. In this embodiment, a cylindrical shape is preferred. The advantage of using a cylindrical shape is that the power of the electromagnetic waves radiated from the reflecting lens is symmetrical in all directions.

[0070] Specifically, the electromagnetic wave reflector is made of metal and is mainly used to reflect electromagnetic waves transmitted to the electromagnetic wave reflector. In this embodiment, the electromagnetic wave reflector is made of aluminum plate or copper plate, among other things.

[0071] Specifically, at the location with the largest metal surface area per unit volume, the metal surface area gradually decreases in the radial direction towards the periphery; or, decreases in steps; or decreases periodically.

[0072] It should be noted that step reduction means that the reduction of the metal surface area is not a continuous and smooth decrease, but rather that there may be some obvious inflection points or plateaus during the decrease, causing the rate of decrease to slow down or stop near these points, thus forming a step-like shape.

[0073] Periodic decrease refers to the fact that during the process of decreasing the surface area of ​​the metal, its value exhibits a periodic downward trend. This periodic change usually means that within a certain fixed time interval, the value of the curve will undergo a complete rise and fall process, and this process will repeat, forming periodic fluctuations.

[0074] Specifically, the antenna aperture surface refers to the cross-section of the planar reflective antenna, and the control surface is the antenna aperture surface that outputs electromagnetic waves.

[0075] In order to enable the planar reflective antenna to achieve a large beam scanning angle when the subsequent feed moves on the antenna aperture surface, while ensuring that the gain does not drop significantly, a gradient refractive index is constructed on the antenna aperture surface, as shown in Figure 2.

[0076] More specifically, let n0 be the electromagnetic refractive index at the location with the largest unit volume of the metal surface area, w be the height between the upper and lower opposing surfaces of the paper substrate, and r be the radial distance extending circumferentially around n0. Then, the refractive index n(r) at position r conforms to the following inverse hyperbolic cosine distribution law:

[0077] n(r) = n0sech(πr / (4w)).

[0078] It should be noted that the larger the surface area of ​​the metal, the larger the value of n0, and the larger the final refractive index n(r); however, in practical applications, the value of n0 is generally between 1 and 3. Higher values ​​of n0 are also possible, but they would be relatively difficult to implement.

[0079] According to the above formula, the refractive index corresponding to each point on the antenna aperture surface can be calculated. The specific refractive index distribution on the antenna aperture surface is shown in Figure 2. The refractive index is the highest at the center of the antenna aperture surface, and the refractive index gradually decreases from the center along the surrounding edges.

[0080] Specifically, the symbol unit is disposed on the sidewall surrounding and facing the cavity structure, and the unit volume covers at least one cavity structure in the planar direction and contains at least one symbol unit in the vertical direction; in this embodiment, this means that at least one cavity structure is included in the transverse plane of the reflecting lens, and at least one symbol unit is included in the vertical plane perpendicular to the transverse plane.

[0081] At least some of the hole structures have different arrangement density, size, or shape of the symbol units compared to other hole structures. It should be noted that within the same paper substrate, the symbol units of different hole structures may differ. In this embodiment, different equivalent dielectric constants can be obtained by adjusting the symbol units.

[0082] Specifically, the paper base material includes aramid paper.

[0083] More specifically, the paper base includes, but is not limited to, being made of aramid paper or flexible PCB board, and the symbol unit is fixed to the aramid paper or flexible PCB board by printing or attaching.

[0084] It should be noted that in the reflective lens, the paper base mainly plays a supporting role, while the paper base made of aramid paper used in this embodiment has a unique spatial structure and mechanical properties; moreover, aramid paper has excellent chemical inertness, can self-extinguish immediately after leaving the fire source, and has good heat insulation, temperature resistance, electrical insulation and electromagnetic wave transmission properties.

[0085] The cavity structure is a circular or polygonal three-dimensional columnar void structure.

[0086] In this embodiment, the cavity structure can specifically be a hexagonal three-dimensional columnar cavity structure. The hexagonal three-dimensional columnar cavity structure gives the paper base body good axial compressive and impact resistance, as well as excellent sound insulation and fatigue resistance. It also allows the reflective lens to have a lower density, so the overall weight is lighter than other materials. Moreover, the hexagonal cavity structure allows subsequent electromagnetic waves to be radiated in the form of plane waves, which can achieve large-angle radiation while ensuring that the gain does not decrease significantly.

[0087] In this embodiment, in order to achieve an equivalent gradient refractive index, the symbol unit is first set on the sheet paper base, and then different equivalent refractive indices are achieved by adjusting the size of the symbol unit.

[0088] It should be noted that the medium within the cavity structure is air, which has a dielectric constant of 1.0. The dielectric constant of the paper substrate is different from that of air. To increase the equivalent dielectric constant of the reflective lens, the final equivalent dielectric constant can be changed by adjusting the side length of each side of the symbol unit.

[0089] Specifically, the shape of the symbol unit includes, but is not limited to, an open ring, a cross shape, or a circular ring.

[0090] When the symbol unit is an open ring, the equivalent dielectric constant can be changed by adjusting the length of each side of the open ring; wherein, the length of the side is positively correlated with the equivalent dielectric constant, that is, the longer the side is, the higher the equivalent dielectric constant.

[0091] More specifically, the equivalent dielectric constant ranges from 1 to 2.

[0092] As shown in Figure 5, this embodiment changes the equivalent dielectric constant by printing an open ring structure on aramid paper. The change in equivalent dielectric constant is mainly achieved by adjusting the side length of each side of the open ring.

[0093] It should be noted that: This embodiment uses electromagnetic simulation software for simulation; according to theory and simulation results, when the area ratio of the symbol cell to the single sidewall of the hole structure is the same, the final equivalent dielectric constant is similar regardless of how the shape and density of the symbol cell are changed.

[0094] The symbol unit is made of a highly conductive metal material, such as silver paste or copper, with silver paste being the preferred choice in this embodiment.

[0095] This embodiment also provides a planar reflective antenna for wide-angle, high-gain applications, including the aforementioned reflective lens; and,

[0096] The feed source is positioned close to and inverted on the control surface, which is a plane; the electromagnetic wave is reflected and propagated within the reflective lens in a curved path, and then collimated and emitted outside the reflective lens.

[0097] As shown in Figure 3, in a planar reflector antenna, electromagnetic waves incident on the reflector plane are reflected and then converge toward the control surface along a curved path, finally exiting the reflector lens in the form of a plane wave.

[0098] The feed source is a moving feed source, and the moving trajectory extends along a straight line or a plane and corresponds to the control surface; so that a single moving feed source can achieve the technical effect of scanning.

[0099] Alternatively, the feed source is a fixed feed source, which has multiple feed sources arranged along a straight line or plane and corresponding to the control surface; in this embodiment, the effect of multiple beams is achieved by setting multiple feed sources at the same time, with one feed source corresponding to one beam; under the condition of multiple beams, multiple electromagnetic waves at different angles will be emitted in the form of plane waves in different directions after being emitted.

[0100] More specifically, the output surfaces of the electromagnetic waves from the multiple feed sources are located at the same height.

[0101] Specifically, the focal plane of the reflective lens is set to coincide with the control plane, and the feed source is installed close to the surface of the paper-based main body to ensure that large-angle electromagnetic wave radiation and high antenna gain can be achieved subsequently.

[0102] It should be noted that traditional antennas generally have only one central focal point, and the feed needs to be placed at the central focal point, extending along the central focal point and perpendicular to the optical axis to form a plane. If the feed is placed on this plane away from the central focal point, the focusing effect of the electromagnetic waves emitted by the feed will be worse. However, the entire incident plane of the reflective lens described in this embodiment is the focal plane. The refraction effect of the electromagnetic waves emitted by the feed at any position on the focal plane is basically the same. This embodiment will not have the problem of a sharp drop in antenna gain and a smaller antenna beam scanning angle.

[0103] As shown in Figures 8-9, regardless of where the feed source is installed on the control surface, the gain of the planar antenna will change as the beam scanning angle changes. Taking the feed source 3 in Figure 9 as an example, as the beam scanning angle of the reflecting lens changes from 0 degrees to ±50 degrees, the gain will periodically decrease from 20 dBi.

[0104] More specifically, the electromagnetic wave emitted by a feed source located at any position on the focal plane has a gain roll-off of less than 2dB after being radiated by the reflecting lens; where gain roll-off refers to the gain of different beams relative to the maximum gain of all beams.

[0105] As shown in Figure 10, the gain of different beam scanning angles varies with frequency, but in the wide frequency range of 1.8 GHz to 3.8 GHz, the gain drop of different beam scanning angles is within 2 dB. Taking the beam scanning angle of 0 degrees in Figure 10 as an example, when the frequency changes from 2.0 GHz to 2.1 GHz, the gain drop is significantly less than 2 dB.

[0106] Furthermore, in existing technologies, the feed sources of parabolic antennas and reflector antennas are suspended at the center focal point, which is difficult to install. In contrast, the feed source of the reflecting lens described in this embodiment is directly installed along the plane. Planar installation is simpler and more convenient than suspension installation. Therefore, compared to existing parabolic antennas and reflector antennas, the planar reflector antenna of this embodiment is easier to install. In this embodiment, whether using aramid paper or a flexible PCB board, under the same volume conditions, both are significantly lighter than ceramic, which helps reduce the transportation cost of the planar reflector antenna. Moreover, for manufacturers, the larger the antenna volume, the higher the processing cost of ceramic, but the processing cost of aramid paper is lower than that of ceramic. Therefore, the planar reflector antenna described in this embodiment is also conducive to large-scale production.

[0107] As shown in Figure 3, this embodiment illustrates the propagation path of electromagnetic waves inside the reflecting lens. Unlike parabolic antennas and reflector antennas, due to the presence of the paper-based main body, symbol elements, and electromagnetic wave reflector, after the feed emits electromagnetic waves from different positions, the electromagnetic waves reach the reflecting plane in a curved form and are then reflected by the electromagnetic wave reflector. The reflected electromagnetic waves then reach the antenna aperture surface and propagate into free space in the form of plane waves. Therefore, by placing the feed at different positions on the control surface, the electromagnetic waves can be radiated in the form of plane waves, thus achieving both large-angle radiation and preventing a significant drop in gain.

[0108] Moreover, the wide-angle scanning bandwidth achieved by the planar reflective antenna in this embodiment can reach 80%, which is much wider than the bandwidth of a traditional planar transmission antenna.

[0109] Example 2

[0110] This embodiment provides another lightweight paper-based reflective lens for electromagnetic wave beam modulation. Features not explained in this embodiment can be explained using the methods described in Embodiment 1, and will not be repeated here. The difference between this embodiment and Embodiment 1 is as follows:

[0111] The paper base was replaced with a plastic material.

[0112] Based on the disclosure and teachings of the foregoing specification, those skilled in the art can make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the present invention should also fall within the protection scope of the claims of the present invention. Furthermore, although some specific terms are used in this specification, these terms are only for convenience of explanation and do not constitute any limitation on the present invention.

Claims

1. A lightweight paper-based reflective lens for electromagnetic wave beam modulation, comprising a paper-based body, characterized in that, The paper-based body is formed by surrounding periodically spaced void structures with sheet-like paper bases. It has two opposing surfaces, an upper surface and a lower surface, which are the control surface and the reflection surface of electromagnetic waves, respectively. The sheet-like paper base has distributed symbol units made of thin film-like metallic material attached to it; The symbol unit is compared with the metal surface area of ​​the symbol unit per unit volume in the paper base body. The metal surface area per unit volume in the middle of the paper base body is greater than that in the periphery of the paper base body. The reflective plane has an electromagnetic wave reflector plate on its surface.

2. The lightweight paper-based reflective lens for electromagnetic wave beam modulation according to claim 1, characterized in that, The control surface is a plane and is set parallel to the reflecting plane; The paper base body is cylindrical, polygonal, or frustum-shaped. The cavity structure is a circular or polygonal three-dimensional columnar void structure.

3. The lightweight paper-based reflective lens for electromagnetic wave beam modulation according to claim 1, characterized in that, At the location with the largest metal surface area per unit volume, the metal surface area gradually decreases radially towards the circumference; or, decreases in steps; or decreases periodically.

4. The lightweight paper-based reflective lens for electromagnetic wave beam modulation according to claim 1 or 3, characterized in that, Let n0 be the electromagnetic refractive index at the location with the largest unit volume of the metal surface area, w be the height between the upper and lower opposing surfaces of the paper substrate, and r be the radial distance extending circumferentially with n0 as the center. Then the refractive index n(r) at position r conforms to the following inverse hyperbolic cosine distribution law: n(r) = n0sech(πr / (4w)).

5. The lightweight paper-based reflective lens for electromagnetic wave beam modulation according to claim 1 or 2, characterized in that, The symbol unit is disposed on the sidewall surrounding and facing the cavity structure, and the unit volume covers at least one cavity structure in the planar direction and contains at least one symbol unit in the vertical direction; The arrangement density, size, or shape of the symbol units within at least part of the cavity structure differs from that of another part of the cavity structure.

6. The lightweight paper-based reflective lens for electromagnetic wave beam modulation according to claim 1, characterized in that, The paper base material includes aramid paper.

7. The lightweight paper-based reflective lens for electromagnetic wave beam modulation according to claim 1, characterized in that, The electromagnetic wave reflector is made of metal.

8. A planar reflector antenna for wide-angle, high-gain applications, characterized in that, Including the reflective lens as described in any one of claims 1-7; and, The feed source is positioned close to and inverted on the control surface, which is a plane; the electromagnetic wave is reflected and propagated within the reflective lens in a curved path, and then collimated and emitted outside the reflective lens.

9. The planar reflective antenna according to claim 8, characterized in that, The feed source is a mobile feed source, the movement trajectory of which extends along a straight line or a plane and corresponds to the control surface; or, the feed source is a fixed feed source, there are multiple of them, arranged along a straight line or a plane and corresponding to the control surface.

10. The planar reflective antenna according to claim 8, characterized in that, The focal plane of the reflective lens is set to coincide with the control surface, and the feed source is mounted close to the surface of the paper base body; The gain roll-off of electromagnetic waves emitted by a feed source located at any position on the focal plane after being radiated by the reflecting lens is less than 2dB.

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