JPH0547001B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a radio wave lens, and particularly to a radio wave lens (dielectric lens) using a dielectric material.

[Conventional technology]

Among radio wave lenses that apply lens effects such as reflection and convergence to incoming radio waves, radio wave lenses such as Luneberg lenses and Eaton Lipman lenses that use plastic dielectrics (e.g. foamed polyethylene) are used for maritime rescue and navigation aids. It is widely used in various fields including radar reflectors for commercial use.

In the case of such a radio wave lens (also referred to as a dielectric lens), for example, a spherical radio wave lens, its relative dielectric constant ε _r is expressed by a predetermined relational expression, ie, ε _r = [2-(r/a)
² ] (where a: radius of the spherical lens, r: distance from the center) to gradually change the refractive index n
It is necessary ^to _change
Engineering Handbook, SECOND EDISION
pp. 18-3, Richard C. Johnson et al.).

For this reason, it is not possible to simply manufacture a conventional radio wave lens according to theory, so a multilayer structure is created in which the entire spherical radio wave lens is divided into mutually polymerizable bowl-shaped hemispherical shells. A commonly used method was to set the permittivity of each of these hemispherical shells to a predetermined value. Further, in this case, as a technique for varying the dielectric constant and setting it to a predetermined value, a method of artificially adjusting the proportion of metal grains (for example, aluminum grains) mixed into the hemispherical shell has often been used.

[Problem that the invention seeks to solve]

However, in the above-mentioned conventional technology,
The more we try to form a precise radio lens by making the change in permittivity of the radio lens as continuous as possible from the center to the outer periphery, the more the number of hemispherical shells mentioned above must be increased, so the mold becomes more difficult. This inevitably increases the number of parts and the manufacturing process, resulting in a significant increase in price.

On the other hand, when foaming plastic while changing the ratio of metal particles mixed in, a lot of skill is required for the molding process, and depending on the value of the dielectric constant, it is difficult to mix the metal particles uniformly. There are many
There were disadvantages such as a decrease in yield and a decrease in performance as a lens.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to improve the disadvantages of the prior art and, in particular, to provide a radio wave lens which is significantly easier to manufacture and which can significantly reduce production costs.

[Means for solving problems]

In the present invention, a large number of small pieces of conductive foil are arranged on a sheet-like insulating planar substrate, and the density of the conductive foil is gradually coarsened concentrically from the center and toward the outer periphery. A plurality of dielectric members are provided, each of which is changed as follows. The respective dielectric members are stacked at predetermined intervals with their center portions arranged on the same axis, and the dielectric member located at least in the center of the stacked body exhibits a ratio The dielectric constant ε _r is ε _r = [2−(r/
a) A large number of small pieces of conductive foil are arranged so as to vary according to ² ] (where a: the maximum radius of the area where the conductive foil is attached concentrically, and r: the distance from the center). The structure is such that there are This aims to achieve the above-mentioned purpose.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 to 5.

First, in FIG. 1, reference numeral 2 indicates a Luneberg lens. This Luneberg lens 2 includes an artificial dielectric plate 4 as a thin sheet-like dielectric member.
_A ,...,4 _M (However, 4 _A only has 1 piece, the others have 2 pieces each)
and each of these artificial dielectric plates 4 (hereinafter, the subscripts " _A " to " _M " are removed as necessary)
The main part includes foamed polystyrene plates 6, . And each artificial dielectric plate 4
The styrofoam plates 6 are stacked alternately as shown in the figure, and each dimension is set in advance so as to form a spherical shape as a whole.

Here, reference numeral 8 indicates a groove (actually, it becomes a groove in the laminated state) formed in a concave shape on the outer periphery of each artificial dielectric plate 4 and the foamed polystyrene plate 6 as a guide means for positioning. This groove 8
is also used to fix the entire Luneberg lens 2, as will be described later.

To explain the Luneberg lens 2 in more detail, each artificial dielectric plate 4 in this embodiment consists of a total of 25 sheets, and 12 artificial dielectric sheets are placed above and below each other through the central artificial dielectric plate _4A . Body plates _4B to _4M are arranged symmetrically as shown in FIG. and,
The artificial dielectric plates 4 are stacked at predetermined intervals, and in this state, the dimensions are set so that the profile in the lateral direction is circular as shown in FIGS. 1 and 2.

Each of the artificial dielectric plates 4 is made of YUPO paper 10 (thickness approximately
20μ) and disc _- shaped conductor foils 12, . In this embodiment, the conductive foils 12, . It's getting old. The printing density of each conductor foil 12 is as described below.
Starting from the center, the roughness is concentric and stepwise, and the radius of distribution is set to be different in each artificial dielectric plate 4. As will be described later, the conductive foils 12,...,1 are placed inside the Luneberg lens 2 starting from the center thereof.
This is to form layered and concentric spherical shells A ₁ to A ₅ due to the difference in density between the two (see FIG. 2).

Here, typical conductor foil density patterns among the artificial dielectric plates 4 are shown in FIGS. 3 1 to 5.

FIG. 3 1 shows the artificial dielectric plate 4 in the center mentioned above.
Indicates _A. In this dielectric plate 4 _A , the first circular area B ₁ (radius r ₁ ) in the center has the highest conductor foil density.
The second, third, and fourth circular areas B ₂ , B ₃ , and B ₄ (the radius is r ₂
to r ₄ ) are printed, and a circular area B ₅ (radius r ₅ ) where no conductive foil is printed is set on the outer periphery. The density of the conductor foil is formed to have a predetermined density gradient toward the outer periphery and to become rough in a stepwise manner as described above.

In addition, FIG. 3 2 shows the artificial dielectric plate 4 _A described above.
The fifth artificial dielectric plates _4F and _4F are shown, centered on . In the case of these dielectric plates 4 _F and 4 _F , the outer radius r ₆ is smaller than r ₅ in FIG. 1 by a predetermined value, so that each of the first to fifth circular areas
B ₁ to B ₅ are also formed so that each radius becomes smaller by a predetermined value.

Further, FIG. 3 shows the eighth artificial dielectric plates 4 _I and 4 _I above and below the artificial dielectric plate 4 _A. In each of these dielectric plates 4 _I and 4 _I , the outer radius r ₇ is formed smaller, and at the same time, the first circular area B ₁ where the conductor plate density is the highest is not formed, and the second or Only the fifth circular areas B ₂ to B ₅ are formed in the same manner as described above.

34 to 5 show the 10th or 12th artificial dielectric plate _4K , which is formed in the same manner as described above.
_4K , _4M and _4M are shown respectively.

Here, artificial dielectric plates 4 other than those mentioned above,...
4 is also formed in the same manner as FIGS. 1 to 5.

On the other hand, each foamed polystyrene board 6 is used to three-dimensionally arrange and support each artificial dielectric board 4 at a predetermined distance apart, and to increase the overall strength. In this embodiment, while taking into consideration the dielectric constant of the foamed polystyrene board 6, it is formed to be relatively thin at the center and relatively thick as it approaches the upper and lower ends. This is to provide a more precise refractive index at the center.
These foamed polystyrene plates 6 have a multilayer divided structure in which the styrofoam plates 6 form a spherical shape as a whole in their laminated state.

The artificial dielectric plates 4 and the foamed polystyrene plates 6 formed as described above are stacked alternately while being positioned by each groove 8 as shown in FIG. By binding and fixing with a string-like member, the first
As shown in the figures, a spherical Luneberg lens 2 is formed.

As a result, the Luneberg lens 2 as a whole has _concentric spherical shells A ₁ to A ₅ (the outer periphery of which has a radius
r ₁ to r ₅ ) are formed in a layered manner as shown by the two-dot chain line in FIG. Here, the relative permittivity ε _r of the spherical shell A ₁ at the center is "2", and as it approaches the outer periphery, ε _r = 2 - R ² (where R is the normalized radius, and at the outer periphery R = The outermost spherical shell is gradually changed into a step-like shape based on the relational expression ``1'').
The distribution density of the conductor foils 12,..., 12 on each artificial dielectric board 4 is set so that the relative dielectric constant _{ε r} of A ₅ is "1", taking into consideration the dielectric constant of the styrofoam board 6. .

In this case, in this embodiment, the above-mentioned Yupo paper 10
Since the thickness of the paper 10 is selected to be sufficiently thin relative to the wavelength of the incoming radio waves (for example, 9375 [MHz]), the dielectric constant of the YUPO paper 10 can be ignored, simplifying the design. It is being

Next, the operation of this embodiment will be explained.

The dielectric constant _{ε r} of the spherical Luneberg lens 2 configured as described above gradually changes in five stages from "1" to "2" as it progresses from the outer periphery to the center. Therefore, the electromagnetic waves incident parallel to the lens 2 are focused at a point P on the lens surface opposite to the direction of incidence as shown in FIG. 5, as in the case of the conventional Luneberg lens.
The electromagnetic waves converge. Conversely, the electromagnetic wave radiated inward from one point P on the lens surface becomes a plane wave due to the difference in dielectric constant of the layers, that is, the lens effect, and as shown in FIG. It will be emitted from the lens surface. Therefore,
By equipping the surface of the lens with a reflector centered at one point P, it can easily function as a radar reactor.

Here, it is constructed in the same manner as the Luneberg lens 2 described above (that is, artificial dielectric plates are alternately laminated by foamed polystyrene plates), and a disc-shaped conductive foil 12 is constructed.
A principle model in which the elements are arranged in three dimensions (see Figure 6, 1).
I will explain about it. In this principle model, the diameter d of each conductor foil 12 was set to 2 [mm], and the distances a and b between the center lines of the conductor foils 12 in the same artificial dielectric board were both set to 3 [mm]. And this is 9375 [M
When an electromagnetic wave (horizontally polarized wave) of Hz] is incident parallel to an artificial dielectric plate, the relationship between the coupling coefficient (vertical distance between the artificial dielectric plates) c and the refractive index n is shown in Figure 6-2. Experiments have shown that the result looks like the X mark.

In addition, theoretically, the refractive index n of the above principle model
is known to be given by n=√ _r・_r , where ε _r is the relative permittivity, μ _r is the relative permittivity, and ε _r =1+α _e /[ε _p (1−α _e C )] μ _r =1+α _n /[μ _p (1−α _n C)]. Here, α _e is the polarizability, α _n is the magnetic susceptibility, C is the aforementioned coupling coefficient, and ε _p and μ _p are the permittivity and magnetic permeability in vacuum, respectively.

The calculation results using the above relational expressions (see the solid line in FIG. 6, 2) are in good agreement with the experimental results.

Furthermore, it is known that the qualitative relationship between the density and permittivity of conductive foil in a dielectric is generally as shown in FIG. 7, and the higher the distribution density, the higher the relative permittivity.

Therefore, when the distribution density of the conductive foil is changed, the relative dielectric constant changes, and there is a coupling coefficient where the refractive index n becomes √2 or more (see Fig. 6, 2). It has been confirmed that the Luneberg lens 2 can be manufactured by configuring as shown in the figure and appropriately setting each value.

As described above, according to this embodiment, small pieces of conductive foil are formed on a thin sheet-like insulating planar substrate by printing to have a predetermined distribution density, and then these are laminated with a styrofoam plate interposed therebetween. As a result, it has become possible to obtain a radio wave lens having a structure equivalent to that of a conventional technique in which metal particles are mixed in a dielectric material with a predetermined distribution. Since the conductive foil is also formed using printing technology, it can be easily produced in large quantities, which eliminates the hassles of foaming technology found in conventional examples, making it extremely easy to manufacture the entire lens. This has the advantage that production costs can be significantly reduced accordingly. In addition, since the desired conductor foil can be arranged extremely precisely by printing on Yupo paper, the three-dimensional arrangement of the conductor foil in the laminated state can also be done more precisely. It also has the advantage that the focal length etc. can be adjusted more easily and precisely than the conventional example. Furthermore, by adopting the method of this embodiment, there is an advantage that it is possible to achieve a reduction in weight and size while having performance equivalent to or better than that of the conventional example. Furthermore,
The use of a laminated member has the advantage that it is easy to increase the strength of the entire lens, and it also allows the use of paper material on which conductive foil can be easily printed as an insulating planar substrate.

In the above embodiments, a spherical Luneberg lens has been described as a radio wave lens, but the present invention is not necessarily limited to this, and can be similarly applied to an Eaton Lipman lens or the like. In addition, even in the case of this spherical radio wave lens, by forming each of the artificial dielectric plates 4 into a square shape and the conductor foil into a circular shape as described above, the whole lens can have a square shape. However, in terms of electromagnetic waves, it is also possible to form a spherical radio wave lens inside. Further, in the above embodiment, the case of a spherical radio wave lens was shown, but
The present invention is not necessarily limited to this, but for example, the artificial dielectric plate 4 _A shown in FIG.
A cylindrical Luneberg lens can also be formed by manufacturing and laminating a large number of lenses, thereby making it possible to diversify the implementation of the present invention. Furthermore, by making the printing density of the conductor foil within the artificial dielectric plate constant, a monostatic lens can also be easily formed.

On the other hand, in the above embodiment, a styrofoam plate was cut into layers and used as a laminated member.
The present invention is not necessarily limited to this, and other dielectric materials may be used. In this case, if the insulating planar substrates are relatively robust, each substrate is supported by appropriately arranged pillars, and nothing is used as a laminated member (i.e., air). The structure may be simplified and the weight may be reduced.

Further, in the above embodiment, water-resistant Yupo paper is used as the insulating planar substrate, but as described above, other insulating materials may be used as well. Further, the shape of the conductor foil does not necessarily have to be disc-shaped,
The material may also be other materials such as aluminum.

[Effects of the Invention] Since the present invention is configured and functions as described above,
According to this, the method of mixing small pieces of conductive foil into a dielectric material is significantly simpler than the conventional method, and the mixing distribution can be precisely adjusted, so it can be manufactured at a lower cost overall. At the same time, it is possible to obtain extremely precise and stable lens performance, and at the same time, it can be configured to be smaller and lighter than conventional models, making it easier to handle and saving space when attached to the equipment target. Furthermore, it is possible to provide an excellent radio wave lens that has never been seen before, in which the support mechanism can be made smaller.

Furthermore, in the present invention, a cylindrical or spherical radio wave lens can be produced by changing the density of the conductor foil in the dielectric depending on the distance from the center, or by changing the density range appropriately for each dielectric member. Another advantage is that it can be manufactured extremely easily.

Furthermore, in the present invention, by laminating the dielectric member using a laminated member, the lamination process is facilitated, the strength of the entire lens can be easily increased, and the insulation properties of the dielectric member are improved. A thin sheet-like material on which a conductive foil can be easily formed is sufficient as the planar substrate, and this aspect also has the effect of facilitating manufacturing.

Further, according to the present invention, by employing the guide means, it is possible to easily position each component and bind the entire lens.

[Brief explanation of drawings]

FIG. 1 is a partially sectional perspective view of a Luneberg lens according to an embodiment of the present invention, and FIG. 2 is an explanation for explaining layered and concentric spherical shells having different dielectric constants in the Luneberg lens of FIG. 1. Figures 3, 1 to 5
4 is an explanatory diagram showing a typical printing density pattern of conductor foil of an artificial dielectric board, FIG. 4 is an explanatory diagram illustrating a laminated state of an artificial dielectric board and a foamed polystyrene board, and FIGS. 5 1 and 2 are respectively Fig. 6 is an explanatory diagram explaining the lens action of the Luneberg lens in Fig. 1, Fig. 6 1 is an explanatory diagram of the principle model of the Luneberg lens in Fig. 1, and Fig. 6 2 is an illustration of the coupling coefficient and refractive index in Fig. 1. FIG. 7 is a graph diagram illustrating the qualitative relationship between density and dielectric constant of conductive foil. 2... Luneberg lens as a radio wave lens, 4, 4 _A ,..., 4 _M ... Artificial dielectric plate as a dielectric member, 6,..., 6... Styrofoam plate as a laminated member, 8... Guide Groove portion as means, 10... Yupo paper as insulating planar substrate, 1
2,...,12...conductor foil, _A1 ,..., _A5 ...spherical shell.

Claims (1)

[Claims] 1. A large number of small piece-shaped conductor boxes are arranged on a sheet-like insulating planar substrate, and the density of the conductor foil is arranged concentrically from the center toward the outer periphery. A plurality of dielectric members are provided that are gradually roughened, and each of the dielectric members is stacked at a predetermined interval with the center portions of the dielectric members arranged on the same axis. the dielectric constant ε _r exhibited by the dielectric member located at least in the center of the laminate;
The above-mentioned small size is changed so that ε _r = [2-(r/a) ² ] (where a: the maximum radius of the area where the conductor foil is attached concentrically, and r: the distance from the center). A radio wave lens characterized by a large number of strips of conductive foil. 2. The laminate is formed into a columnar shape, and each of the plurality of dielectric members forming the laminate is formed substantially the same as the dielectric member located at the center of the laminate. A radio wave lens according to claim 1, characterized in that: 3 The laminate is formed into a spherical shape, and the relative dielectric constant ε _r in a cross section in any direction including the center of the spherical laminate is the relative permittivity exhibited by the dielectric member located at the center. 2. The radio wave lens according to claim 1, wherein said small piece of conductive foil is attached to each dielectric member of said laminate so as to change in accordance with a change in ε _r . 4. Claim 3, characterized in that the laminated spacing between the dielectric members in the laminate is set to be dense at the center on the central axis and coarse at both ends thereof. Radio wave lens described in section. 5 A large number of small pieces of conductive foil are arranged on a sheet-like insulating planar substrate, and the density of the conductive foil is arranged concentrically from the center and gradually becomes coarser toward the outer periphery. A plurality of dielectric members are provided, each dielectric member is stacked at a predetermined interval with the center of the dielectric member arranged on the same axis, and at least one of the stacked layers is Relative permittivity ε _r exhibited by the dielectric member located in the center
The above-mentioned small size is changed so that ε _r = [2-(r/a) ² ] (where a: the maximum radius of the area where the conductor foil is attached concentrically, and r: the distance from the center). A radio wave characterized in that a large number of strips of conductive foil are arranged, and a solid laminated member made of an insulating material having a predetermined dielectric constant is attached and integrated between each of the dielectric members. lens. 6 A large number of small pieces of conductor foil are arranged on a sheet-like insulating planar substrate, and the density of the conductor foil is arranged concentrically from the center and gradually becomes coarser toward the outer periphery. A plurality of dielectric members are provided, each dielectric member is stacked at a predetermined interval with the center of the dielectric member arranged on the same axis, and at least one of the stacked layers is Relative permittivity ε _r exhibited by the dielectric member located in the center
The above-mentioned small size is changed so that ε _r = [2-(r/a) ² ] (where a: the maximum radius of the area where the conductor foil is attached concentrically, and r: the distance from the center). A large number of strips of conductive foil are arranged, and a solid laminated member made of an insulating material having a predetermined dielectric constant is interposed between each of the dielectric members, and each of the dielectric members and each laminated layer is interposed between each of the dielectric members. A radio wave lens, characterized in that guide means for positioning is provided on a part of the outer periphery of the member, and each of the dielectric members and each laminated member are integrally fixed via the guide means.