JP5250764B2 - Lens antenna - Google Patents

Description

  The present invention relates to a lens antenna suitable for use in a quasi-millimeter wave to millimeter-wave band.

  In recent years, research and development of antennas in a quasi-millimeter wave to millimeter-wave band has been promoted in various fields such as automotive radar and wireless LAN. In this band, a parabolic antenna is usually used when a high gain is required, a standard or horn antenna is used as a measurement system, and a patch antenna is used as a basic antenna of a high-grade one such as a phased array antenna, These antennas are complex in structure and expensive.

  A dielectric lens antenna having a simple structure as compared with these antennas is known. The dielectric lens antenna is designed to transmit and converge radio waves in the same way as an optical lens. The dielectric lens antenna generally has a curved surface shape like a normal optical lens, but a plate-shaped antenna is also proposed. For example, a material having different relative permittivity as in Patent Document 1 is arranged in an annular shape, or a number of through holes are formed as in Patent Document 2, so that the relative permittivity has a spatial distribution. Has been proposed.

In addition, in the non-patent document 1, the inventors of the present application artificially obtain a relative dielectric constant equivalent to a dielectric by providing a large number of small disk-shaped metal flakes on a flat lens body, and the dimensions of the metal flakes. A low profile (thin) lens antenna has been proposed in which the relative permittivity has a spatial distribution by varying (dimension in the direction perpendicular to the lens central axis) according to the distance from the lens central axis. FIG. 11A is a simplified side view showing a lens antenna 101 similar to one exemplified as the lens antenna of Non-Patent Document 1, enlarged in the lens central axis direction. The lens antenna 101 is configured such that the lens body 2 has a plurality of layers (lens layers) 20, 20,. The number of lens layers 20, 20,... Is about 10, for example. For example, the lens antenna 101 has a radius R of 25 mm and a thickness t _L of 1.40 mm. Ce in the figure is the lens central axis of the lens antenna 101. FIG. 11B is a simplified side view showing the lens layer 20 further enlarged in the lens central axis direction. FIG. 12 is a front view of the lens layer 20, where (a) shows the odd-numbered lens layer 20, and (b) shows the even-numbered lens layer 20. Each lens layer 20 is provided with a large number of small metal pieces 22 on a substrate 21, and the dimensions of the metal pieces 22 are varied according to the distance r in the orthogonal direction from the lens center axis Ce. The metal flakes 22 in the odd-numbered lens layer 20 shown in FIG. 12A and the metal flakes 22 in the even-numbered lens layer 20 shown in FIG. By alternately overlapping the lens layers 20 of the eyes and the lens layers 20 of the even number, the face-centered square arrangement of the metal thin pieces 22 is formed.

JP-A-7-86827 JP 2001-85936 A I. Awai, S .; Kida and O.K. Mizue, “Very thin and flat lens antennas of artistic electricals”, Proc of 2007 Korea Microwave Conference, October 2007, pp. 197 177-180

In this lens antenna 101, the dimension of the metal thin piece 22 is derived from the relationship between the dimension of the metal thin piece 22 and the relative dielectric constant ε _L, and the relative dielectric constant ε _L at each position of the lens body 2 is determined from the convergence condition of the radio wave. decided, it will select the size of the metal flakes 22 in response to the dielectric constant epsilon _L. FIG. 13 is a characteristic diagram showing the relationship between the relative dielectric constant ε _L and the dimension (radius ρ) of the metal flakes 22 derived by simulation by the inventor of the present application. In the simulation, the lens body 2 having a face-centered square arrangement is composed of unit cells having a certain size, and the unit cells are used for the simulation. FIG. 14 is a perspective view of a unit cell. The unit cell is composed of two lens layers each having a length Lc, a width Wc of 4 mm, a thickness tc of 0.122 mm of the substrate 21 and a thickness of 18 μm of the thin metal piece 22. As the substrate 21, CCL870M manufactured by Mitsubishi Gas Chemical Co., Ltd. having a relative dielectric constant of 3.27 was assumed. As simulation software, HFSS manufactured by Ansoft, which is a simulator of electromagnetic field distribution, was used.

As shown in FIG. 13, the relative dielectric constant ε _L increases as the radius ρ of the metal flakes 22 increases, and the relative dielectric constant ε _L may be 100 or more when the radius ρ of the metal flakes is about 1.2 mm. it can. When the relative dielectric constant ε _L of about 100 is used, the thickness of the flat lens body 2 can be extremely reduced. However, the higher the dielectric constant epsilon _L of the lens body 2, will be caused a large mismatch for radio waves entering from the air, as a result, the reflection loss of the radio wave is increased.

  The present invention has been made in view of the above reasons, and an object of the present invention is to provide a flat lens antenna capable of reducing the reflection loss of radio waves.

In order to achieve the above object, a lens antenna according to claim 1 is provided on at least one side of the lens main axis direction of the lens body so as to reduce a reflection loss of the radio wave and a flat lens body that transmits the radio wave. is and the antireflector distance of the lens body and substantially the same plate-like to the periphery from the lens center axis, Ri Na and wherein the lens body and the anti-reflection member are both small metal flakes on a substrate Are formed of a plurality of layers, and the dimensions of the metal flakes are varied according to the distance in the orthogonal direction from the lens center axis. The dimensions of the metal flakes are the dimensions of the metal flakes and the relative dielectric constant. Using the relationship and the impedance of the antireflection body side at the boundary between the antireflection body and air and the impedance of the lens body side at the boundary between the antireflection body and the lens body, The relationship between the relative permittivity of the antireflector and the relative permittivity of the lens body, which are guided so that the reflection coefficient at the boundary of the atmosphere is zero or a constant value, and the amount of phase shift when the radio wave passes through the lens antenna And the relative permittivity of the anti-reflective body and the relative permittivity of the lens body, and from the phase shift amount and the center axis of the lens that are guided so that the radio wave radiated from the focal point becomes a plane wave when transmitted through the lens antenna. It is derived using the relationship with the distance in the orthogonal direction .

  The lens antenna according to claim 2 is the lens antenna according to claim 1, wherein the antireflection body is provided on both sides of the lens body.

A lens antenna according to a third aspect is the lens antenna according to the first or second aspect , wherein the lens main body and the metal flakes of the antireflection body are formed by photoetching.

A lens antenna according to a fourth aspect is the lens antenna according to any one of the first to third aspects, wherein the thickness of the antireflection body is larger than the thickness of the lens body.

  According to the lens antenna of the present invention, since the flat antireflection body is provided on at least one side in the lens central axis direction of the flat lens body, the whole is flat, and the reflection loss of radio waves is reduced. It becomes possible to do.

The best mode for carrying out the present invention will be described below with reference to the drawings. FIG. 1A is a simplified side view showing the entire configuration of the lens antenna 1 according to the embodiment of the present invention in an enlarged manner in the lens central axis direction. The lens antenna 1 includes a flat lens body 2 that transmits radio waves similar to the lens antenna 101 described above, and further includes two flat antireflection bodies 3A and 3B on both sides thereof. The lens body 2 and the antireflection bodies 3A and 3B have substantially the same distance R from the lens central axis Ce to the peripheral edge in the orthogonal direction. The lens body 2 is configured by superimposing a plurality of layers (lens layers) 20, 20,..., And the antireflection bodies 3A and 3B are similarly composed of a plurality of layers (antireflection layers) 30, 30,. .. is constructed by overlapping. The sizes of the lens body 2 and the antireflection bodies 3A and 3B are determined in consideration of the radio frequency f of the device to which the lens antenna 1 is applied and the installation space allocated to the lens antenna 1, but in this embodiment, the lens The radius R of the main body 2 and the antireflection bodies 3A and 3B is 25 mm, the thickness t _L of the lens body 2 and the thickness t _A of the antireflection bodies 3A and 3B are both 1.40 mm. FIG. 1B is a simplified side view showing the lens layer 20 further enlarged in the lens central axis direction.

  FIG. 2 is a front view of the lens layer 20 and the antireflection layer 30. (A) is an odd-numbered lens layer 20, (b) is an even-numbered lens layer 20, (c) is an odd-numbered antireflection layer 30, and (d) is an even-numbered antireflection layer 30. Show. Each lens layer 20 is provided with a large number of small disk-shaped metal thin pieces 22 on a substrate 21, and the dimensions of the metal thin pieces 22 are varied according to the distance r in the orthogonal direction from the lens center axis Ce. Further, the metal thin pieces 22 in the odd-numbered lens layers 20 and the metal thin pieces 22 in the even-numbered lens layers 20 are located in a gap between each other when viewed from the front, and the odd-numbered lens layers 20 and the even-numbered lens layers 20. The lens body 2 in which the face-centered square arrangement of the thin metal pieces 22 is formed by alternately stacking the lens layers 20 is configured. In addition, the antireflection layer 30 is provided with a large number of small disk-shaped metal thin pieces 32 on a substrate 31, and the dimensions of the metal thin pieces 32 are varied according to the distance r in the orthogonal direction from the lens center axis Ce. . Further, the metal flakes 32 in the odd-numbered antireflection layer 30 and the metal flakes 32 in the even-numbered antireflection layer 30 are located in a gap between the odd-numbered antireflection layers 30 and the even-numbered antireflection layers 30. The antireflection bodies 3A and 3B in which the face-centered square arrangement of the thin metal pieces 32 are formed by alternately stacking the first antireflection layers 30 are configured.

  The metal flakes 22 and the metal flakes 32 are made of, for example, Cu or Ag, and have a thickness of about 15 to 20 μm. The thin metal pieces 22 and 32 having various dimensions in the lens body 2 and the antireflection bodies 3A and 3B can be easily formed by photoetching. The important point here is that the antireflection bodies 3A and 3B can be easily manufactured by the same substrate and process as the lens body 2.

A design method for determining preferable dimensions of the metal thin pieces 22 and 32 in the lens layer 20 and the antireflection layer 30 will be described below. This design method is: (A): derivation of the relationship between the size of the metal flakes 22 and the relative dielectric constant ε _L (the relationship between the size of the similar metal flakes 32 and the relative dielectric constant ε _A ), and (B): antireflection. The impedance Zi on the antireflection body 3A side at the boundary between the body 3A and the air, the impedance Zj on the lens body 2 side at the boundary between the antireflection body 3A and the lens body 2, and the reflection at the boundary between the lens body 2 and the antireflection body 3B Using the impedance Zk on the prevention body 3B side, the relative permittivity of the reflection prevention bodies 3A and 3B such that the reflection coefficient Re at the boundary between the reflection prevention body 3A and the air becomes zero (satisfying the non-reflection condition of radio waves). Derivation of the relationship between ε _A and the relative dielectric constant ε _L of the lens body 2, (C): phase shift amount Φ and relative dielectric constant ε _A when the radio wave incident on the antireflection body 3 A passes through the entire lens antenna 1. and specific relationship between the dielectric constant epsilon _L Derivation, (D): All the radio waves radiated from the focal point 4 located on the lens central axis Ce of the lens antenna 1 and positioned outside the antireflection body 3A have the same phase when transmitted through the lens antenna 1 ( Derivation of the relationship between the phase shift amount Φ and the distance r in the orthogonal direction from the lens center axis Ce (which becomes a plane wave), (E): metal so that each relationship is traced from (D) to (A) above The dimensions of the thin pieces 22 and 32 are derived. Details will be sequentially described below.

When calculating with specific numerical values, the radio wave frequency f is 18 GHz, the number of lens layers 20 of the lens body 2 is 10, the number of antireflection layers 30 of the antireflection body 3A is 10, and reflection. The number of antireflection layers 30 of the prevention body 3B is 10, the thickness t _L of the lens body 2 and the thickness t _A of the antireflection bodies 3A and 3B are both 1.40 mm, and the relative dielectric constants of the substrate 21 and the substrate 31 are The focal length fo is calculated as 2 cm in order to reduce the loss due to the incident leakage (spillover) to the lens antenna 1.

The design method (A) will be described. The relationship between the radius ρ of the metal flake 22 and the relative dielectric constant ε _L is derived as shown in FIG. 13 described in the section of the problem to be solved by the invention, and the same relationship is derived from the radius ρ of the metal flake 32 and the relative dielectric constant. also it applies to ε _a.

The design method (B) will be described. The non-reflection condition of the radio wave is given by the following equation (1) so that the reflection coefficient Re of the radio wave incident from the air side at the boundary between the air and the antireflection body 3A becomes zero. Z ₀ and Zi are the impedance of air and the impedance on the antireflection body 3A side at the boundary between air and the antireflection body 3A, respectively.

  The lens antenna 1 is represented by an equivalent circuit diagram of FIG. 3A due to the difference in the medium, and the impedance Zi on the antireflection body 3A side at the boundary between air and the antireflection body 3A, the antireflection body 3A and the lens. The impedance Zj on the lens body 2 side at the boundary with the body 2 and the impedance Zk on the antireflection body 3B side at the boundary between the lens body 2 and the antireflection body 3B are given by the following equations (2) to (4), respectively. .

Here, Z ₀ , Z _A , Z _L , β ₀ , β _A , and β _L are given by the following equations (5) to (10). ε ₀ and μ ₀ are air permittivity and permeability, respectively. μ _A and μ _L are the relative magnetic permeability of the antireflection bodies 3A and 3B and the lens body 2, respectively.

When the above equation (1) is solved with relative permeability μ _L and μ _A as 1 for the sake of simplicity, as shown in FIG. 3B, the relative permittivity ε _A has a plurality of relative permittivity ε _L. It becomes a relation of a function having a solution. Thus, it is determined what value the relative dielectric constant ε _A should take with respect to the value of the relative dielectric constant ε _L.

  The important point in this design method (B) is that the lens antenna 1 is flat and extremely thin, and the applied radio wave is very coherent, so that reflection and transmission on both sides of the lens antenna 1 (ie, Reflection and transmission at the boundary between air and the antireflection body 3A, the boundary between the antireflection body 3A and the lens body 2, the boundary between the lens body 2 and the antireflection body 3B, and the boundary between the antireflection body 3B and the air) The design is performed in consideration of the interference caused by This is different from an optical lens in that the lens shape is a curved surface and light rays are incoherent, so that it is not necessary to consider interference due to reflection and transmission on both surfaces of the lens.

The design method (C) will be described. The phase shift amount Φ is a function of the relative dielectric constant ε _A of the antireflection bodies 3A and 3B and the relative dielectric constant ε _L of the lens body 2 and is given by the following equation (11).

Here, when the relationship between the relative permittivity ε _A and the relative permittivity ε _L shown in FIG. 3B is used, the phase shift amount Φ and the relative permittivity ε _L have the relationship as shown in FIG. .

  The design method (D) will be described. FIG. 5A is a schematic diagram showing a state of the radio wave radiated from the focal point 4 in the lens antenna 1. From the following equation (12), the relationship between the phase shift amount Φ and the distance r in the orthogonal direction from the lens center axis Ce is obtained.

Here, if the metal flakes 22 are not present at the periphery (r = R) of the lens body 2, the relative dielectric constant ε _L becomes the relative dielectric constant (= 3.27) of the substrate 21 itself, so that FIG. Accordingly, the phase shift amount Φ (R) at the periphery of the lens antenna 1 is 0.92π [rad]. By substituting this value into the following equation (12 ′) at the periphery of equation (12), the phase shift amount Φ (0) on the lens center axis Ce is obtained.

  FIG. 5B is a diagram showing the relationship between the phase shift amount Φ thus derived and the distance r in the orthogonal direction from the lens center axis Ce. The phase shift amount Φ decreases as the distance r increases. The dotted line portion in the figure will be described later.

The design method (E) will be described. FIG. 6 shows a combination of FIG. 5B in the first quadrant, FIG. 4 in the second quadrant, and FIG. 3B in the third quadrant. Therefore, the positive value of the X axis in FIG. 6 is the distance r in the orthogonal direction from the lens center axis Ce, the positive value of the Y axis is the phase shift amount Φ, the negative value of the X axis is the relative dielectric constant ε _L , and the Y axis. negative values of the relative dielectric constant epsilon _a. Using FIG. 6, the phase shift amount Φ corresponding to the distance r in the orthogonal direction from the lens center axis Ce is obtained in the first quadrant, the relative dielectric constant ε _L satisfying the phase shift amount Φ is obtained in the second quadrant, The relative dielectric constant ε _A can be obtained from the relative dielectric constant ε _{L in} three quadrants. In this way, the relative permittivity ε _L and the relative permittivity ε _A corresponding to the distance r in the orthogonal direction from the lens center axis Ce are derived. Then, using FIG 13, a lens layer 20 that corresponds to the relative dielectric constant epsilon _L and the dielectric constant epsilon _A Request radius ρ of the metal flakes 22 and 32 in the antireflection layer 30.

  When designed in this manner, specific spatial distributions of the thin metal pieces 22 and 32 having various dimensions can be obtained in the lens layer 20 and the antireflection layer 30 shown in FIG. Note that this spatial distribution does not necessarily mean that the dimension (radius ρ) of the metal flakes 22 and 32 simply decreases as the distance r in the orthogonal direction from the lens center axis Ce increases.

  An experiment conducted by the inventor of the present invention by making a prototype of this lens antenna 1 will be described below. FIG. 7 is a configuration diagram of the experiment. In the anechoic chamber 50, the frequency f is 17 GHz, and a rectangular patch antenna (primary radiator) 51 that radiates a directional radio wave with a half value of 32 degrees centering on a direction of ± 180 degrees is converged. A lens antenna 1 for receiving and a horn antenna 52 for receiving radio waves are installed. The lens antenna 1 is a distance of 2 cm, which is a focal length fo, from the patch antenna 51 and is located in a direction of ± 180 degrees. The horn antenna 52 is a distance of 2.5 m from the lens antenna 1 and has a frequency f of 17 GHz. The radio wave gain was measured. FIG. 8 is a directivity diagram of the result. (A) When the lens antenna 1 is used, (b) when the antireflection bodies 3A and 3B are removed and only the lens body 2 is used, and (c) is between the patch antenna and the horn antenna. It is a thing when nothing is attached to. In FIG. 8, the downward direction is the direction of ± 180 degrees, the circle with the maximum radius indicates −50 dB, and the inner circles indicate −60 dB, −70 dB, and −80 dB in order. According to FIG. 8, the amount of reflection is large in the case of (b) without the antireflection bodies 3A and 3B, but the amount of reflection is reduced in the case of (a) where the antireflection bodies 3A and 3B are provided. .

In FIG. 4, the phase shift amount Φ does not exist the value of epsilon _L corresponding thereto in 1.42π~1.94π [rad]. For this purpose, as shown by the dotted line in FIG. 5B, actually, either 1.42π [rad] or 1.94π [rad] was applied during the experiment. The reason why the gain in the case of (a) is not higher than the gain in the case of (b) at the position of ± 180 degrees in FIG. In order to increase the gain at the position of ± 180 degrees, an antireflection design should be used at a radius r where the phase shift amount Φ is 1.42π to 1.94π [rad] even if some reflection is accepted. Although it is possible not to perform this, it is desirable to perform a more complicated design so that the range in FIG. 4 where ε _L corresponding to the phase shift amount Φ does not exist becomes small. Specifically, the relative permittivity ε _A obtained by loosening the non-reflection condition of the above formula (1) or by the metal flakes 32 of the antireflection layer 30 constituting the antireflection bodies 3A and 3B is set in the lens central axis direction. It is possible to change gradually. Among them, it is easy to adjust the thickness t _L of the lens body 2 (that is, the number of lens layers 20) and the thickness t _A of the antireflection bodies 3A and 3B (that is, the number of antireflection layers 30). However, as described below, it is very effective.

In the above design method, specific numerical values are as follows: the number of lens layers 20 of the lens body 2 is 6, the number of antireflection layers 30 of the antireflection body 3A is 12, and the number of antireflection layers 30 of the antireflection body 3B is The thickness t _L of the lens body 2 was 0.84 mm, the thickness t _A of the antireflection bodies 3A and 3B was 1.68 mm, and the others were calculated in the same manner as described above. Then, the relative dielectric constant ε _A and the relative dielectric constant ε _L have a relationship as shown in FIG. 9 different from FIG. 3B, and the phase shift amount Φ and the relative dielectric constant ε _L are different from FIG. The relationship is as shown in FIG. 10B is an enlarged view of a part of FIG. According to FIG. 10B, the range in which ε _L corresponding to the phase shift amount Φ does not exist is 1.68π to 1.70π [rad], which is extremely small. Accordingly, the portion indicated by the dotted line in FIG. 5B can also be made extremely small.

As described above, increasing the thickness t _A of the antireflection bodies 3A and 3B beyond the thickness t _L of the lens body 2 reduces the range in which ε _L corresponding to the phase shift amount Φ does not exist. Desirable results are obtained. The number of lens layers 20 of the lens body 2 is 10, the number of antireflection layers 30 of the antireflection body 3A is 15, and the number of antireflection layers 30 of the antireflection body 3B is 15. As in FIG. 10, it was confirmed that the relationship between the phase shift amount Φ and the relative dielectric constant ε _L can be obtained in a very small range where ε _L corresponding to the phase shift amount Φ does not exist.

  The lens antenna 1 according to the embodiment of the present invention has been described above. Since the lens antenna 1 is a transmission type, it essentially has some reflection loss of radio waves, but the reflection loss can be greatly reduced by providing the antireflection bodies 3A and 3B. The lens antenna 1 has a flat plate shape as a whole, and can maintain a low profile (thinness). Therefore, the complex of the lens antenna 1 and the primary radiator can be optimized to be small, and the lens antenna 1 can be placed in front of an existing antenna (for example, parabolic antenna, horn antenna, patch antenna, etc.). By simply installing it, it is possible to easily increase the gain that is insufficient.

  The present invention is not limited to that described in the above-described embodiment, and various design changes can be made within the scope of the matters described in the claims. For example, in the above embodiment, the case where the antireflection bodies 3A and 3B are provided on both sides of the lens body 2 has been described. However, when radio waves are incident on the lens antenna 1 only from the outside on the antireflection body 3A side, etc. The antireflection body 3B can be omitted. Further, as described with respect to the above-described experiment, the non-reflection condition is relaxed, and the reflection coefficient Re of the radio wave incident at the boundary between the air and the antireflection body 3A is a small constant value (eg, −10 dB) that is not zero. Can also be made.

It is a simplified side view which shows the structure of the lens antenna which concerns on embodiment of this invention. It is an example front view of the lens layer and antireflection layer which comprise the lens antenna same as the above. It is an equivalent circuit diagram of the lens antenna same as the above, and a diagram showing a relationship between a relative permittivity ε _A and a relative permittivity ε _L. It is a figure which shows the relationship between phase shift amount (PHI) and relative dielectric constant (epsilon) _L of a lens antenna same as the above. It is the schematic diagram showing the mode in the lens antenna of the electromagnetic wave radiated | emitted from the focus of the lens antenna same as the above, and is a figure which shows the relationship between phase shift amount (PHI) and the distance r of the orthogonal direction from the lens center axis | shaft Ce. It is the figure which combined FIG.5 (b), FIG.4, and FIG.3 (b). It is a block diagram of the experiment which this inventor performed using the lens antenna same as the above. It is a directivity figure of the result of an experiment same as the above. It is a figure which shows the relationship between the dielectric constant (epsilon) _A and the dielectric constant (epsilon) _L which applied another numerical condition of the lens antenna same as the above. It is a figure which shows the relationship between phase shift amount (PHI) and relative dielectric constant (epsilon) _L which applied another numerical condition of the lens antenna same as the above. It is a simplified side view which shows the conventional lens antenna. It is an example front view of the lens layer which comprises the conventional lens antenna. It is a characteristic view which shows the relationship between the relative dielectric constant (epsilon) _L which this inventor derived, and the dimension (radius (rho)) of a metal flake. It is a perspective view of the unit cell which this inventor used for simulation.

DESCRIPTION OF SYMBOLS 1 Lens antenna 2 Lens main body 20 Lens layer 22 Metal thin piece of lens layer 3A, 3B Antireflection body 30 Antireflection layer 32 Metal thin piece of antireflection layer Ce Lens central axis f Radio frequency fo Focal distance Φ Phase shift amount r Lens main body The distance from the lens central axis of the antireflection body R The radius of the lens body and the antireflection body t _A The thickness of the antireflection body t The thickness of the _L lens body ε _A The relative permittivity of the antireflection body ε The relative permittivity of the _L lens body ρ Metal flake radius

Claims (4)

A flat lens body that transmits radio waves,
A flat antireflection body that is provided on at least one side of the lens body in the lens central axis direction so as to reduce the reflection loss of radio waves, and whose distance from the lens central axis to the periphery is substantially the same as that of the lens body. Do Te Ri,
The lens body and the antireflection body are both composed of a layer in which a large number of small metal flakes are provided on a substrate, and the dimensions of the metal flakes are varied according to the distance in the orthogonal direction from the lens central axis.
The dimensions of the metal flakes are
The relationship between the dimensions of the metal flakes and the dielectric constant
The reflection coefficient at the boundary between the antireflection body and air is zero or at least using the impedance on the antireflection body side at the boundary between the antireflection body and air and the impedance on the lens body side at the boundary between the antireflection body and the lens body. The relationship between the relative permittivity of the antireflector guided to a constant value and the relative permittivity of the lens body,
The relationship between the phase shift amount when radio waves pass through the lens antenna, the relative permittivity of the antireflection body, and the relative permittivity of the lens body,
The relationship between the phase shift amount guided so that the radio wave radiated from the focal point becomes a plane wave when passing through the lens antenna and the distance in the orthogonal direction from the lens central axis,
A lens antenna characterized by being guided by using a lens. The lens antenna according to claim 1, wherein
The lens antenna, wherein the antireflection body is provided on both sides of the lens body. The lens antenna according to claim 1 or 2 ,
The lens antenna, wherein the lens main body and the metal flakes of the antireflection body are formed by photoetching. The lens antenna according to any one of claims 1 to 3 ,
A lens antenna, wherein the thickness of the antireflective body is larger than the thickness of the lens body.

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