Double-layer artificial medium based multi-beam Luneburg lens antenna, control method and application

Abstract

The present invention belongs to the field of antenna technology and discloses a double-layer artificial dielectric multi-beam Luneburg lens antenna, a control method, and an application thereof, comprising an upper cover plate, a lower cover plate, a cylindrical Luneburg lens, and a feeding system. The cylindrical Luneburg lens is divided into two layers, an inner layer and an outer layer, and a gradient dielectric constant effect is achieved by drilling holes in the inner layer's high dielectric constant medium and filling the outer layer's low dielectric constant medium. The feeding system includes a waveguide power divider and a feeding horn. Furthermore, by utilizing a design in which the periphery of the lens is air, the end of the horn is embedded in the lens to ensure that its phase center coincides with the focal line of the lens. The feeding system and the two cover plates jointly perform a fixing and feeding function. The present invention makes lens processing simpler and focusing more accurate. Furthermore, by utilizing a feeding method combining a power divider with multiple small-sized horns, a wider azimuth beam width is achieved compared to single-horn feeding. Rapid scanning coverage within a wide angular range can be achieved by switching fewer feeding ports and switches.

Description

Technical Field

[0001] The present invention belongs to the field of antenna technology, and in particular relates to a double-layer artificial medium multi-beam Luneburg lens antenna, a control method and an application thereof. Background Art

[0002] Currently, there is an increasing demand for multi-beam antennas in radio systems such as satellite communications, radar detection, and electronic countermeasures. Specifically, these applications require antenna systems to simultaneously or time-share multiple beams to cover a specific area of ​​space, meeting the system's communication, detection, navigation, and jamming requirements over large spatial areas. To ensure signal transmission quality and speed, antennas are often required to possess both a very wide beamwidth and a wide frequency bandwidth. Beam-scanning systems based on phased arrays offer significant advantages in beam steering, but they are significantly limited by their high cost and inability to simultaneously transmit multiple beams with full aperture gain. In this context, the use of multiple feeds combined with lens antennas has become a highly competitive and low-cost multi-beam antenna format, with the Luneburg lens antenna being a typical example.

[0003] The concept of the Luneburg lens antenna was first proposed by SK Luneburg in the 1940s. Theoretically, the dielectric constant of a Luneburg lens follows a 2 to 1 pattern from the inner layer to the surface. A cylindrical Luneburg lens antenna is a rotationally symmetrical lens antenna. Every point on the lens surface can be considered a focal point. Therefore, by placing multiple feed antennas on the lens cylinder, multi-beam performance with good beam consistency can be achieved. This allows for wide-angle scanning by switching the feeds, and simultaneous multi-beam operation can be achieved using multiple feed sources. More importantly, the Luneburg lens itself is frequency-insensitive; its operating frequency band is determined by the frequency band of the feed source, making it suitable for high-capacity broadband communication systems.

[0004] The above analysis reveals the following problems and drawbacks of the existing technology: Traditional Luneburg lens antennas, fed by a single feed source, form a narrow beam, requiring more switching cycles to cover the entire search range, making it difficult to meet the demands of some applications requiring fast, wide-range scanning. Furthermore, in terms of practical processing, the current material processing technologies for Luneburg lens antennas primarily include foaming and punching. Using these technologies alone requires multi-layer stacking, which presents drawbacks such as high processing difficulty, high cost, and difficulty controlling the effect. Furthermore, as lens antennas, they place stringent requirements on feed source focus alignment, which also poses a design challenge for this type of antenna.

[0005] The difficulty in solving the above problems and defects is as follows: in terms of wide beam forming, if the feed source beam is changed by changing the shape of the feed horn, thereby widening the azimuth beam width of the Luneburg lens antenna, it is difficult to ensure that the feed source is an approximate point source relative to the lens, and is in a divergent state, making it difficult to guarantee the gain, and the beam gain still shows a large drop as it moves away from the axis. In terms of actual processing, the conventional method of drilling holes in a single high dielectric constant medium, at the edge, due to the large difference between the dielectric constant of the substrate and the theoretically required dielectric constant, the corresponding hole distribution is more dense, which greatly affects the strength of the cylindrical Luneburg lens edge. In addition, the phase center of the feed source horn is often embedded in the horn, and a conflict occurs between the physical lens and the horn, making it impossible for the horn phase center to be located on the focal line of the lens.

[0006] The significance of resolving the above issues and defects lies in: forming a wide beam through compact multi-horn feeding, which can achieve full coverage and fast scanning within a wide angle range by switching fewer feed ports. In terms of processing and manufacturing, the lens body is divided into two layers, inner and outer, and equivalently processed by punching and filling respectively. This can not only improve processing accuracy but also ensure the strength of the outermost low-dielectric constant portion. If a design can be used where the periphery of the lens gradually transitions to air, the end of the horn can be embedded in the lens to ensure that its phase center coincides with the lens focal line, resulting in more accurate focusing and improved antenna performance. Summary of the Invention

[0007] In response to the problems existing in the prior art, the present invention provides a double-layer artificial medium multi-beam Luneburg lens antenna, a control method and an application.

[0008] The present invention is achieved by providing a double-layer artificial dielectric multi-beam Luneburg lens antenna, wherein the double-layer artificial dielectric multi-beam Luneburg lens antenna is provided with:

[0009] Upper cover, lower cover, cylindrical Luneburg lens, and feeding system;

[0010] The cylindrical Luneburg lens and the feeding system are located between the upper cover plate and the lower cover plate. The feeding system is combined with the two cover plates to jointly play the role of fixing and feeding.

[0011] Furthermore, the cylindrical Luneburg lens is divided into two layers, including an inner layer medium and an outer layer medium. The inner layer high dielectric constant medium is punched with holes, and the hole distribution is gradually denser from the inside to the outside; the outer layer low dielectric constant medium is filled with high dielectric constant dielectric filaments, and the filling distribution is gradually sparse from the inside to the outside, so as to achieve an equivalent gradient dielectric constant effect from 2 to 1 from the inside to the outside of the overall relative dielectric constant.

[0012] Furthermore, the outer contour of the outer layer of low dielectric constant medium is an I-shape, and its dielectric constant tends to 1.

[0013] Furthermore, the aperture of the inner layer of high dielectric constant medium is smaller than 1 / 10 of the antenna operating wavelength.

[0014] Furthermore, the diameter of the material filled with the outer layer of low dielectric constant medium is less than 1 / 10 of the antenna operating wavelength.

[0015] Furthermore, the feeding system includes a waveguide power splitter and a feeding horn, which are connected; and combined with the middle and outer lenses, the end of the horn is embedded in the lens to ensure that the phase center of the feeding horn coincides with the focal line of the lens;

[0016] The waveguide power splitter is an E-plane 1-to-M power splitter. The feeding system includes N of the above waveguide power splitters. The angle between adjacent waveguide power splitters is α*N.

[0017] The feed horn is an H-plane fan-shaped horn, and the feed system includes M*N of the above feed horns, and the angle between adjacent feed horns is α.

[0018] Another object of the present invention is to provide a control method for the double-layer artificial dielectric multi-beam Luneburg lens antenna, the control method comprising: selecting foam as the base material for the outer layer of the cylindrical Luneburg lens with a low dielectric constant, whose dielectric constant is 1.13, and filling corresponding segments with dielectric filaments of a higher dielectric constant at corresponding densities. Selecting a dielectric plate with a dielectric constant of 2.2 as the base material for the inner layer of the cylindrical Luneburg lens with a high dielectric constant, and punching holes in corresponding segments at corresponding densities; the diameters of the filled dielectric filaments and the punched holes should be less than 1 / 10 of the working wavelength; for each specific filling and punching density of each segment, the volume ratio is calculated according to the formula, and then determined by the target dielectric constant, filling or punching size, lens base size, and processing requirements, and the best result is obtained through optimization;

[0019] The feeding system includes a waveguide power splitter and a feeding horn, which are connected. The design of the lens periphery is air, so that the end of the horn is embedded in the lens to ensure that its phase center coincides with the focal line of the lens. The waveguide power splitter is an E-plane T-shaped power splitter with a power of 1 to M. The feeding system includes N such waveguide power splitters, and the angle between adjacent waveguide power splitters is α*N. The feeding horn is an H-plane fan-shaped horn, and the feeding system includes M*N such feeding horns, and the angle between adjacent feeding horns is α.

[0020] The M output ports of each waveguide power divider are connected to M feed horns, and the input port is the input port of the entire antenna; when each port of the antenna is working, the Luneburg lens is actually fed by M compact and small-sized feed horns.

[0021] Furthermore, the dielectric constant of the Luneburg lens of the control method satisfies the variation rule of 2 to 1 from the inner layer to the surface, which is specifically expressed as:

[0022]

[0023] Where R is the radius of the lens, r is the distance from a point inside the lens to the center of the sphere, and ε r represents the relative dielectric constant at r;

[0024] The Luneburg lens phenomenon was originally described primarily for spherical lenses, specifically describing the transformation of spherical wave rays emitted from the surface of a sphere into plane wave rays after passing through the lens. This spherical Luneburg lens evolved into the cylindrical Luneburg lens, simplifying the problem from a three-dimensional to a two-dimensional one. The characteristic of a cylindrical Luneburg lens is that any point on the cylindrical surface can be considered the lens's focal point. If this point is used as the feed point, the electromagnetic wave emitted from the aperture plane tangent to this point should be of equal phase. In effect, the cylindrical wave emitted from this focal point is transformed into a plane wave after traversing the lens. Therefore, the path of each ray from the feed point to the aperture plane tangent to this point must have equal electrical length. Theoretical derivation led to the aforementioned relationship between the dielectric constant and radius. When the feed source at the focal point emits a standard cylindrical wave, the lens achieves maximum aperture utilization. Since the focal point of a cylindrical Luneburg lens coincides with the cylindrical surface itself, the horn end can be embedded in the lens to ensure that its phase center coincides with the lens' focal point.

[0025] For the Luneburg lens, the continuous value of the dielectric constant along the radius is divided into n discrete and fixed approximate values. The nth segment is the outermost layer of the lens, with a dielectric constant of 1, which is realized by the outer I-shaped outer profile with a low dielectric constant. The first to n-1 segments are artificially equivalent using the equivalent medium theory, and are divided into two layers, inner and outer, and equivalent by punching and filling respectively to ensure equivalent accuracy. The punching and filling methods used are based on the A-BG equivalent medium theory, and the calculation formula is as follows:

[0026]

[0027] where ε eff is the equivalent dielectric constant of the mixed material, ε i is the dielectric constant of the filling material, ε h is the dielectric constant of the base material, and p is the volume ratio of the equivalent filling material to the volume of the entire mixed material.

[0028] Another object of the present invention is to provide a satellite communication radio system comprising the double-layer artificial medium-based multi-beam Luneburg lens antenna.

[0029] Another object of the present invention is to provide a radar detection radio system comprising the double-layer artificial medium-based multi-beam Luneburg lens antenna.

[0030] Combining all the above technical solutions, the advantages and positive effects of the present invention are as follows: the lens part of the present invention is simple to process, and two processing methods, punching and filling, are used according to specific needs, so that the equivalent dielectric constant is closer to the theoretical value. The present invention utilizes a design in which the periphery of the lens gradually changes to air, so that the end of the horn is embedded in the lens to ensure that its phase center coincides with the focal line of the lens, thereby forming more accurate focusing and improving antenna performance. The antenna of the present invention utilizes N feeding ports as a whole, which are connected to M*N small-sized feeding horns through a power divider structure. When switched to each port for operation, the actual feed source of the lens is M compact small-sized horn antennas, thereby achieving a wide beam in the azimuth plane, and then full coverage and rapid scanning in a wide-angle range can be achieved by switching fewer feeding switches. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 1 is a schematic structural diagram of a double-layer artificial dielectric multi-beam Luneburg lens antenna provided by an embodiment of the present invention;

[0032] Figure 2 Schematic diagram of the structure of the waveguide power splitter and the feed horn provided in an embodiment of the present invention;

[0033] Figure 3 Schematic diagram of the structure of dielectric filaments filled in the outer lens provided by an embodiment of the present invention;

[0034] Figure 4 is an angle-gain simulation result diagram provided by an embodiment of the present invention;

[0035] Figure 5 3D schematic diagram of the feeding structure of a single feeding horn according to an embodiment of the present invention;

[0036] Figure 6 3. This is a diagram of angle-gain simulation results comparing the feeding of a single feeding horn of the present invention provided by an embodiment of the present invention;

[0037] In the figure: 1. Upper cover; 2. Lower cover; 3. Outer lens; 31. Dielectric filament filled with outer lens; 4. Inner lens; 41. Hole drilled in inner lens; 51. Waveguide power divider; 52. Feed horn. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0039] In response to the problems existing in the prior art, the present invention provides a double-layer artificial medium multi-beam Luneburg lens antenna, a control method and an application. The present invention is described in detail below with reference to the accompanying drawings.

[0040] like Figure 1 、 Figure 2 and Figure 3 As shown, the present invention provides a double-layer artificial dielectric multi-beam Luneburg lens antenna comprising an upper cover plate 1, a lower cover plate 2, a Luneburg lens located between the two, and a feed system. The Luneburg lens comprises an outer lens 3 and an inner lens 4. The outer lens is filled with a high-permittivity dielectric filament 31, while the inner lens is perforated with a through-hole 41. The feed system consists of a waveguide power splitter 51 connected to a feed horn 52. This system, combined with the upper and lower cover plates 1 and 2, provides both securement and power supply.

[0041] Theoretically, the dielectric constant of the Luneburg lens follows a 2 to 1 variation rule from the inner layer to the surface, which can be expressed as:

[0042]

[0043] Where R is the radius of the lens, r is the distance from a point inside the lens to the center of the sphere, and ε r represents the relative dielectric constant at r.

[0044] To facilitate fabrication, the Luneburg lens's continuous dielectric constant distribution along the radius is divided into n discrete, fixed approximate values. Segment n, the outermost layer of the lens, has a dielectric constant of 1, achieved by utilizing the outer, low-dielectric-constant I-shaped profile. Segments 1 through n-1 are artificially equated using the equivalent medium theory, and are divided into two layers, respectively, equated using punching and filling to ensure equivalent accuracy. The punching and filling methods employed here are based on the A-BG equivalent medium theory. The calculation formula is as follows:

[0045]

[0046] where ε eff is the equivalent dielectric constant of the mixed material, ε i is the dielectric constant of the filling material, ε h is the dielectric constant of the base material, and p is the volume fraction of the equivalent filler material to the entire mixed material volume. This rule is applicable to the case where the base dielectric constant is close to the required dielectric constant, and is suitable for the specific application scenarios of the present invention.

[0047] In the present invention, foam is selected as the base material for the low dielectric constant medium of the outer layer of the cylindrical Luneburg lens, and its dielectric constant is 1.13. In the corresponding segments, dielectric filaments with higher dielectric constants are filled with corresponding densities. A dielectric plate with a dielectric constant of 2.2 is selected as the base material for the high dielectric constant medium of the inner layer of the cylindrical Luneburg lens, and holes are punched in the corresponding segments with corresponding densities. In order to meet the macroscopic equivalence requirements, the diameters of the filled dielectric filaments and the punched holes should be less than 1 / 10 times the working wavelength. For each segment, the specific filling and punching density, after the volume ratio is calculated according to the formula, needs to be determined by the target dielectric constant, filling or punching size, lens base size, and processing technology requirements, and the best result is obtained through optimization.

[0048] The feed system consists of a waveguide power splitter and a feed horn, which are connected. The lens is designed with air surrounding the end of the horn, so that its phase center coincides with the focal line of the lens. The waveguide power splitter is an E-plane T-shaped power splitter with an M-division ratio. The feed system contains N such waveguide power splitters, with the angle between adjacent waveguide power splitters being α*N. The feed horn is an H-plane fan-shaped horn, and the feed system contains M*N such feed horns, with the angle between adjacent feed horns being α. The angle α should be neither too small nor too large, as it must ensure that the antenna radiation beam meets the angular coverage requirements and that the feed source is approximately a point source relative to the Luneburg lens. The M output ports of each waveguide power splitter are connected to M feed horns, and the input port is the input port of the entire antenna. When each port of the antenna is working, M compact and small-sized feed horns actually feed the Luneburg lens, thereby realizing a wide beam in the azimuth plane. In turn, full coverage and rapid scanning in a wide-angle range can be achieved by switching fewer feed switches.

[0049] The technical effects of the present invention are described in detail below with reference to simulations.

[0050] Figure 5 This is a schematic diagram of the three-dimensional structure of a single feed horn feeding according to the present invention. The number and angle of the feed horns shown in the figure are not fixed and are only for comparison and explanation.

[0051] The technical effects of the present invention are further described in detail below in conjunction with an example simulation experiment where M=4 and N=4.

[0052] like Figure 4 and Figure 6 As shown, electromagnetic simulation software is used to perform simulation calculations within the Ka frequency band. Figure 4 This is a diagram of the angle-gain simulation results of the present invention. As shown in the figure, 36 sets of data within a 1.25 octave range are given when the four ports are working separately. Figure 6This is a graph comparing the angle-gain simulation results of a single feed horn according to the present invention. As shown, 14 sets of data at the center frequency are presented for each of the 14 ports operating. In both figures, the horizontal axis represents the azimuth angle in degrees, and the vertical axis represents the normalized gain in dB. The horizontal line indicates the normalized pattern's -3dB beamwidth, and curves with different peaks represent the different directional radiation patterns produced by the antenna when each port is operating.

[0053] Since the Luneburg lens itself is not sensitive to frequency, the radiation patterns generated at various frequencies when the same feed port operates are roughly the same, so the following description uses the radiation pattern at the center frequency as an example. Figure 4 It is shown in the figure that the 4-port switching beam coverage of the antenna of the present invention is 85.54 degrees, and the 3dB beam widths of the 4 ports when they are fed are 19.41 degrees, 19 degrees, 18.99 degrees, and 19.41 degrees respectively. Figure 6 It is shown in the figure that if the beam coverage range of the antenna of the present invention is to be achieved, the comparison antenna requires 14 ports for switching, and the 3dB beam widths of the 14 ports when each is fed are 18.54deg, 16.65deg, 16.88deg, 17.7deg, 17.24deg, 17deg, 17.73deg, 17.74deg, 17deg, 17.24deg, 17.7deg, 16.87deg, 16.64deg, and 18.5deg respectively.

[0054] It can be seen that due to the addition of a power splitter structure in the feeding system, four small-sized feeding horns are combined for feeding, so that each port of the antenna works to widen the generated beam width. This can not only meet the beam coverage requirements, but also avoid the waste caused by the overlap of radiation patterns. This means that in practical applications, fewer port switching operations can be used to achieve the same beam scanning coverage requirements, which facilitates the realization of full coverage and fast scanning in a wide-angle range.

[0055] In the description of the present invention, unless otherwise specified, "plurality" means two or more; terms such as "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," and "tail" indicate positions or relationships based on those shown in the accompanying drawings. These terms are intended solely to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limiting the present invention. Furthermore, terms such as "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0056] The above description is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with this technical field within the technical scope disclosed by the present invention and within the spirit and principles of the present invention should be covered by the scope of protection of the present invention.

Claims

1. A multi-beam Luneburg lens antenna based on a double-layer artificial medium, characterized in that: The double-layer artificial medium multi-beam Luneburg lens antenna is provided with: Upper cover, lower cover, cylindrical Luneburg lens, and feeding system; The cylindrical Luneburg lens and the feeding system are located between the upper cover and the lower cover. The feeding system is combined with the two covers to jointly play the role of fixing and feeding. The cylindrical Luneburg lens is divided into two layers, including an inner dielectric layer and an outer dielectric layer. The inner dielectric layer with a high dielectric constant is perforated, with the perforations distributed gradually denser from the inside out; the outer dielectric layer with a low dielectric constant is filled with high dielectric constant filaments, with the filling distribution gradually sparser from the inside out, so that the overall relative dielectric constant presents an equivalent gradient dielectric constant from 2 to 1 from the inside out. The control method based on a double-layer artificial dielectric multi-beam Luneburg lens antenna includes: selecting foam as the substrate material of the low dielectric constant dielectric of the outer layer of the cylindrical Luneburg lens, the dielectric constant of which is 1.13, and filling corresponding sections with dielectric filaments of a higher dielectric constant at corresponding densities; selecting a dielectric plate with a dielectric constant of 2.2 as the substrate material of the high dielectric constant dielectric of the inner layer of the cylindrical Luneburg lens, and drilling holes in corresponding sections at corresponding densities; the diameters of the filled dielectric filaments and the drilled holes should both be less than 1 / 10 of the operating wavelength; for each section, the specific filling and drilling density is determined by calculating the volume ratio according to a formula, and then determined based on the target dielectric constant, the filling or drilling size, the lens substrate size, and the processing requirements, and the optimal result is obtained through optimization; The feeding system includes a waveguide power splitter and a feeding horn, which are connected. The lens is surrounded by air, so that the end of the horn is embedded in the lens to ensure that its phase center coincides with the focal line of the lens. The waveguide power splitter is an E-plane T-shaped power splitter with an M-to-M ratio. The feeding system includes N waveguide power splitters, and the angle between adjacent waveguide power splitters is The feed horn is an H-shaped fan-shaped horn, and the feed system includes The above-mentioned feed horns, the angle between adjacent feed horns is ; The M output ports of each waveguide power divider are connected to M feed horns, and the input port is the input port of the entire antenna. When each port of the antenna is working, M compact and small-sized feed horns actually feed the Luneburg lens. The dielectric constant of the Luneburg lens of the control method satisfies the variation rule of 2 to 1 from the inner layer to the surface, which is specifically expressed as: ， Where R represents the radius of the lens, r represents the distance from a point inside the lens to the center of the sphere, represents the relative dielectric constant at r; For the Luneburg lens, the continuous value of the dielectric constant along the radius is divided into n discrete and fixed approximate values. The nth segment is the outermost layer of the lens, with a dielectric constant of 1, which is realized by the outer I-shaped outer profile with a low dielectric constant. The first to n-1 segments are artificially equivalent using the equivalent medium theory, and are divided into two layers, inner and outer, and equivalent by punching and filling respectively to ensure equivalent accuracy. The punching and filling methods used are based on the A-BG equivalent medium theory, and the calculation formula is as follows: ， in is the equivalent dielectric constant of the mixed material, is the dielectric constant of the filling material, is the dielectric constant of the substrate material, is the volume ratio of the equivalent filling material to the volume of the entire mixed material; The feeding system includes a waveguide power divider and a feeding horn, which are connected; the outermost layer of the lens transitions to air, so that the end of the horn is embedded in the lens to ensure that the phase center of the feeding horn coincides with the focal line of the lens; The waveguide power splitter is an E-plane 1-to-M power splitter. The feeding system includes N of the above waveguide power splitters. The angle between adjacent waveguide power splitters is ; The feed horn is an H-face fan-shaped horn, and the feed system includes The above-mentioned feed horns, the angle between adjacent feed horns is .

2. The double-layer artificial medium multi-beam Luneburg lens antenna according to claim 1, characterized in that: The outer contour of the outermost low dielectric constant medium is an I-shape.

3. The double-layer artificial medium multi-beam Luneburg lens antenna according to claim 1, characterized in that: The aperture of the holes punched in the inner layer of high dielectric constant medium is smaller than 1 / 10 of the antenna operating wavelength.

4. The double-layer artificial medium multi-beam Luneburg lens antenna according to claim 1, wherein: The diameter of the object filled with the outer layer of low dielectric constant medium is less than 1 / 10 of the antenna working wavelength.

5. A satellite communication radio system comprising the double-layer artificial dielectric multi-beam Luneburg lens antenna according to any one of claims 1 to 4.

6. A radar detection radio system comprising the double-layer artificial dielectric multi-beam Luneburg lens antenna according to any one of claims 1 to 4.

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