Radio wave lens, manufacturing method thereof, and antenna device

Abstract

To provide a radio wave lens that is thin and has desired antenna characteristics, an antenna device including the radio wave lens, and a method for manufacturing the radio wave lens with high productivity.SOLUTION: An antenna device includes a flat dielectric plate 1 arranged perpendicular to the transmission direction of radio waves, and a radio wave reflector 2. The dielectric plate 1 has a thickness t1 in the transmission direction of radio waves which is expressed by the following formula, and the dielectric plate 1 and the reflector 2 are arranged at positions such that the distance d1 between the first surface 1a of the dielectric plate 1 and the reflecting surface 2a of the reflector 2 is expressed by the following formula (ε2 is the relative dielectric constant of the region 4 between the first surface 1a and the reflecting surface 2a). The reflector 2 has a cutout 3 through which radio waves pass, and the radio wave lens 100 forms a laminate of the dielectric plate 1, a foam plate 7, and the reflector 2.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a thin radio wave lens, a manufacturing method thereof, and an antenna device. [Background technology]

[0002] 2. Description of the Related Art In wireless communication devices, sensors, wireless power transmission systems, and the like that use radio waves in the microwave or millimeter wave frequency bands, antenna devices play an important role as interfaces for transmitting or receiving radio waves.

[0003] In recent years, with the miniaturization of wireless communication circuits mounted on wireless communication devices and the like, antenna devices have been miniaturized by forming an antenna section on a dielectric substrate. On the other hand, desired antenna characteristics such as directivity and antenna gain are required for antenna devices. Antenna gain is determined almost entirely by the aperture area of ​​the antenna. For this reason, the wireless communication device described in Patent Document 1 discloses a configuration in which a convex lens (radio wave lens) is provided at the aperture from which radio waves are emitted. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2000 / 048269 Summary of the Invention [Problem to be solved by the invention]

[0005] Conventionally proposed radio wave lenses need to be convex, and need to be placed at a certain distance from the antenna element, taking into account the focal length of the convex shape. This makes it difficult to make the radio wave lens and the antenna device including the radio wave lens thin. Furthermore, when manufacturing a convex radio wave lens, it is necessary to use a mold, for example, to mold it, which causes a problem of low productivity.

[0006] Therefore, an object of the present invention is to provide a radio wave lens that is thin and has desired antenna characteristics, an antenna device that includes this radio wave lens, and a method for manufacturing the radio wave lens with high productivity. [Means for solving the problem]

[0007] The radio wave lens according to one aspect of the present invention is a radio wave lens comprising a flat dielectric plate arranged perpendicular to the direction of transmission of radio waves, and a radio wave reflector arranged parallel to the dielectric plate, the dielectric plate having a thickness t1 in the direction of transmission of radio waves of: TIFF2025070158000002.tif1264 (where λ0 is the free space wavelength of the radio wave to be transmitted, and ε1 is the relative dielectric constant of the dielectric plate), and the dielectric plate and the reflector are such that a distance d1 between a first surface of the dielectric plate facing the reflector and a reflecting surface of the reflector facing the dielectric plate is: TIFF2025070158000003.tif1264 (ε2 is the relative dielectric constant of the region between the first surface and the reflective surface), and the reflector is configured to have a cutout portion through which radio waves pass.

[0008] A method for producing a radio wave lens according to another aspect of the present invention is a method for producing a radio wave lens provided with a flat dielectric plate arranged perpendicular to the transmission direction of radio waves, the method including the steps of forming a laminate which is an assembly of a plurality of radio wave lenses, in which a dielectric plate, a foam plate, and a reflector are laminated, and dividing the laminate into individual pieces, and the individual pieces of the radio wave lens have a thickness t1 of the dielectric plate as follows: TIFF2025070158000004.tif1264 (where λ0 is the free space wavelength of the transmitted radio wave, and ε1 is the relative dielectric constant of the dielectric plate), and the thickness t2 of the foam plate is TIFF2025070158000005.tif1264 (ε3 is the relative dielectric constant of the foam board), and the reflector is configured to have a cutout portion that allows radio waves to pass through and a radio wave reflecting surface.

[0009] Another aspect of the antenna device of the present invention is an antenna device including the radio wave lens, and an antenna section for transmitting and / or receiving radio waves is arranged at a position where the radio waves pass through the cutout portion. Effect of the Invention

[0010] According to the radio wave lens of the present invention, by arranging a flat dielectric plate of a specified thickness and a reflector at a distance shorter than the wavelength of the transmitted radio waves, it is possible to obtain a radio wave lens that is thin and has the desired antenna characteristics.

[0011] Furthermore, according to the manufacturing method of the radio wave lens of the present invention, a laminate is formed in which a dielectric plate, a foam plate, and a reflector are stacked, and then the laminate is singulated to form a radio wave lens, resulting in a highly productive manufacturing method.

[0012] Furthermore, according to the antenna device of the present invention, by providing a radio wave lens that has been made thin, it is possible to obtain an antenna device that can be made thin and has desired antenna characteristics. [Brief description of the drawings]

[0013] [Figure 1] 1 is an explanatory diagram of an embodiment of a radio wave lens according to an aspect of the present invention. FIG. [Diagram 2] 2 is a diagram illustrating radiation of radio waves from the radio lens of FIG. 1. [Diagram 3] 2 is a diagram illustrating the reflection of radio waves at a dielectric plate and a reflector of the radio wave lens of FIG. 1. [Figure 4] FIG. 11 is an explanatory diagram of another embodiment of a radio wave lens of the present invention. [Diagram 5] FIG. 11 is an explanatory diagram of still another embodiment of the radio wave lens of the present invention. [Figure 6] FIG. 11 is an explanatory diagram of one embodiment of a method for producing a radio wave lens, which is another aspect of the present invention, illustrating a step of forming a laminate. [Figure 7]FIG. 11 is an explanatory diagram of one embodiment of a method for producing a radio wave lens, which is another aspect of the present invention, illustrating a step of singulating a laminate. [Figure 8] 10 is an explanatory diagram of an embodiment of an antenna device according to still another aspect of the present invention. FIG. [Figure 9] 9 is a graph showing the output characteristics of the antenna device shown in FIG. 8. [Figure 10] 9 is a graph showing the output characteristics of the antenna device shown in FIG. 8 in polar coordinates. [Figure 11] 11 is a graph showing the output characteristics of an antenna device not including a radio wave lens. [Figure 12] 13 is a graph showing the output characteristics of an antenna device not including a radio wave lens, in polar coordinates. [Figure 13] 10 is an explanatory diagram of another embodiment of an antenna device according to still another aspect of the present invention. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Next, embodiments of the radio wave lens and antenna device of the present invention, and an implementation of a method for manufacturing a radio wave lens will be described with reference to the drawings; however, the present invention is not limited to these embodiments and implementations, and the members, materials, etc. described below can be modified in various ways within the scope of the spirit of the present invention. Also, in the drawings, the same symbols indicate equivalent or identical items, and the size and positional relationships between each component are for the sake of convenience.

[0015] (Radio wave lens) Fig. 1 is an explanatory diagram of an embodiment of a radio wave lens according to an aspect of the present invention. The radio wave lens 100 of this embodiment shown in Fig. 1 is composed of a dielectric plate 1 made of a flat dielectric material, and a reflector 2 arranged parallel to this dielectric plate 1. In the radio wave lens 100 of this embodiment, radio waves are transmitted in the left-right direction of the drawing.

[0016] The dielectric plate 1 can be selected from low-loss dielectrics that can be used in general radio wave lenses, such as polypropylene resin, acrylonitrile butadiene styrene (ABS) resin, acrylic resin, tetrafluoroethylene resin, polystyrene resin, polycarbonate resin, polybutylene terephthalate resin, polyphenylene resin, Teflon (registered trademark) resin, etc.

[0017] The dielectric plate 1 of this embodiment has a thickness t1 shown in FIG. It is set to TIFF2025070158000006.tif1264, where λ0 is the free space wavelength of the transmitted radio wave, and ε1 is the relative dielectric constant of the dielectric plate 1.

[0018] The reflector 2 has a reflecting surface 2a arranged parallel to the flat dielectric plate 1, and is configured as a metal plate or at least a substrate whose surface is covered with a metal film. The reflector 2 has a cutout portion 3 where a part is cut out. When the radio wave lens 100 of this embodiment is attached to an antenna device for transmitting or receiving radio waves, it is attached so that the antenna part of the antenna device, for example a patch antenna, is exposed from the cutout portion 3. At that time, the arrangement, size, etc. of the cutout portion 3 are set according to the shape, etc. of the antenna part so that the center of the patch antenna and the center of the radio wave lens 100 can be arranged to overlap with each other.

[0019] The dielectric plate 1 and the reflector 2 are disposed at a predetermined distance from each other, and a region 4 is formed between the dielectric plate 1 and the reflector 2. In particular, in this embodiment, the distance d1 between the first surface 1a of the dielectric plate 1 facing the reflector 2 and the reflecting surface 2a of the reflector 2 facing the dielectric plate 1 shown in FIG. TIFF2025070158000007.tif1264. Here, ε2 is the relative dielectric constant of region 4 between the first surface 1a of the dielectric plate 1 and the reflecting surface 2a of the reflector 2. Therefore, when region 4 is filled with air, ε2=1, and when region 4 is filled with a dielectric, ε2 has a value according to the dielectric that fills region 4.

[0020] Next, a case where radio waves are transmitted through the radio lens of this embodiment will be described. Fig. 2 is a diagram for explaining the radiation of radio waves from the radio lens 100 shown in Fig. 1. Radio waves are incident on the radio lens 100 from a feed point 5 shown in Fig. 2. The feed point 5 will be described as a point that is the center of a transmitting antenna section of an antenna device to which the radio lens 100 is attached, for example, a patch antenna. The radio waves that are incident on the region 4 of the radio lens 100 from the feed point 5 are partly reflected by the dielectric plate 1, and partly radiated from the dielectric plate 1.

[0021] 3 is a diagram for explaining the reflection of radio waves at the dielectric plate 1 and reflector 2 of the radio wave lens 100 of FIG. 1. As shown in FIGS. 2 and 3, in the dielectric plate 1, a reflected wave 1 is generated by reflection at a first surface 1a of the dielectric plate 1, and a reflected wave 2 is generated by reflection at a second surface 1b of the dielectric plate 1. Here, the thickness t1 of the dielectric plate 1 in this embodiment is TIFF2025070158000008.tif1264, the reflected waves 1 and 2 are in phase at the first surface 1a. As a result, the reflected waves 1 and 2 are synthesized to generate a constructive composite wave, which is transmitted through the region 4.

[0022] In the region 4, the distance d1 between the first surface 1a of the dielectric plate 1 and the reflecting surface 2a of the reflector 2 is TIFF2025070158000009.tif1264 is set. Therefore, the composite wave of reflected waves 1 and 2 reaches reflector 2 and is reflected by reflecting surface 2a, producing reflected wave 3, which is in phase with the radio wave incident from feed point 5 when it transmits through area 4 and reaches dielectric plate 1 again. As a result, reflected wave 3 and the radio wave incident from feed point 5 reinforce each other at first surface 1a of dielectric plate 1, with some of them passing through dielectric plate 1 and being radiated into space, and some of them transmitting through area 4 as reflected waves 1 and 2 and being reflected again by reflecting surface 2a.

[0023] In this way, the radio waves incident from the power supply point 5 are repeatedly reflected and combined, spreading horizontally relative to the surface of the flat dielectric plate 1 and radiating into space from the second surface 1b of the dielectric plate 1. The radio waves radiated from the entire surface of the second surface 1b of the dielectric plate 1 are in phase, which is equivalent to the antenna aperture being widened. Furthermore, when transmitting radio waves via the radio wave lens 100 of this embodiment, the directivity of the antenna is narrowed and the antenna gain in the front direction increases. Furthermore, the radio wave lens 100 of this embodiment is composed of a flat dielectric plate 1, and the distance between the dielectric plate 1 and the reflector 2 is approximately 1 / 2 the wavelength of the radio waves to be transmitted, making it possible to provide a thin radio wave lens.

[0024] Similarly, when radio waves are incident via the radio wave lens 100 of this embodiment, part of the radio waves incident on the radio wave lens passes through the dielectric plate 1 and part is reflected by the second surface 1b of the dielectric plate 1. Part of the radio waves incident on the dielectric plate 1 is reflected by the reflector 2, and this reflected wave is incident on the dielectric plate 1 again. This radio wave incident on the dielectric plate 1 has an opposite phase to the incident wave reflected by the second surface 1b of the dielectric plate 1, so the reflection on the second surface 1b of the dielectric plate 1 is cancelled out. For this reason, even in the case of reception, the radio waves incident on the entire aperture surface of the radio wave lens are collected at the power feed point 5 while repeatedly reflecting between the dielectric plate 1 and the reflector 2.

[0025] In this way, when radio waves are received through the radio wave lens of this embodiment, radio waves from the desired direction can be received with higher gain, so not only does the sensitivity of the receiving antenna section of the antenna device increase, but the narrowing of the directivity attenuates the incidence of radio waves other than those coming from the desired direction, i.e., unwanted radio waves and noise, thereby improving the effective S / N ratio.

[0026] Next, an embodiment in which region 4 of radio wave lens 100 shown in Fig. 1 is filled with air will be described. Fig. 4 is an explanatory diagram of another embodiment of a radio wave lens of the present invention. Radio wave lens 100A of this embodiment shown in Fig. 4 is composed of a dielectric plate 1 made of a flat dielectric material, a reflector 2 arranged parallel to this dielectric plate 1, and a spacer 6 that supports the dielectric plate 1 and the reflector 2 in parallel.

[0027] The dielectric plate 1 can be selected from low-loss dielectric materials that can be used in general radio wave lenses, similar to the radio wave lens 100. Similarly, the spacer 6 can be selected from low-loss dielectric materials that can be used in general radio wave lenses. The dielectric plate 1 and the spacer 6 can be configured as an integrated unit. The spacer 6 is not limited to a dielectric material, and can be configured as a separate body from the dielectric plate 1.

[0028] The reflector 2, like the radio wave lens 100, can be configured as a metal plate or at least a substrate having a surface covered with a metal film, with a reflecting surface 2a arranged parallel to the flat dielectric plate 1. The reflector 2 has a cutout portion 3 where a portion is cut out. When the radio wave lens 100A of this embodiment is attached to an antenna device for transmitting or receiving radio waves, it is attached so that an antenna portion of the antenna device, for example a patch antenna, is exposed from the cutout portion 3. At that time, the arrangement, size, etc. of the cutout portion 3 are set according to the shape, etc. of the antenna portion so that the center of the patch antenna and the center of the radio wave lens 100A can be arranged to overlap with each other.

[0029] In this embodiment, the dielectric plate 1 has a thickness t1 shown in FIG. 4, similar to the radio wave lens 100. 2 and 3, the reflected wave 1 generated at the first surface 1a of the dielectric plate 1 and the reflected wave 2 generated at the second surface 1b of the dielectric plate 1 are in phase at the first surface 1a, and the reflected wave 1 and the reflected wave 2 are synthesized to generate a constructive composite wave that is transmitted through the region 4.

[0030] The dielectric plate 1 and the reflector 2 have a distance d1 between the first surface 1a of the dielectric plate 1 facing the reflector 2 and the reflecting surface 2a of the reflector 2 facing the dielectric plate 1, which is the same as the radio wave lens 100. TIFF2025070158000011.tif1264. Here, in the radio wave lens 100A of this embodiment, since the region 4 is filled with air, ε2=1. Therefore, the height h of the spacer 6 shown in FIG. 4 is set to h=λ0 / 2.

[0031] The dielectric plate 1 and the reflector 2 supported by the spacer 6 having the height h set in this way are arranged in parallel with an interval approximately equal to the height of the spacer 6 through an air layer constituting the region 4. Therefore, as described in Figs. 2 and 3, a part of the radio wave incident on the radio wave lens 100A from the power feed point 5 is reflected by the dielectric plate 1, and a part of the radio wave is radiated from the dielectric plate 1. The reflected wave 1 reflected by the first surface 1a of the dielectric plate 1 and the reflected wave 2 reflected by the second surface 1b of the dielectric plate 1 are in phase at the first surface 1a. As a result, the reflected wave 1 and the reflected wave 2 are synthesized to form a constructive composite wave, which is transmitted through the region 4. The composite wave of the reflected wave 1 and the reflected wave 2 reaches the reflector 2 and is reflected by the reflecting surface 2a. When the reflected wave 3, which is a composite wave of the reflected wave 1 and the reflected wave 2, transmits through the region 4 and reaches the dielectric plate 1 again, it is in phase with the radio wave incident from the power feed point 5. As a result, the reflected wave 3 and the radio wave incident from the feed point 5 reinforce each other at the first surface 1a of the dielectric plate 1, part of which passes through the dielectric plate 1 and is radiated into space, and part of which transmits through the area 4 as reflected waves 1 and 2 and is reflected again by the reflecting surface 2a. In this way, the radio wave incident from the feed point 5 spreads in the horizontal direction relative to the surface of the flat dielectric plate 1 by repeated reflection and synthesis, and is radiated in phase into space from the entire second surface 1b of the dielectric plate 1. Therefore, with the radio wave lens 100A as well, narrow directivity and high antenna gain in the front direction due to that directivity can be obtained.

[0032] Like the radio wave lens 100 described above, the radio wave lens 100A of this embodiment also functions as a radio wave lens for transmission or reception.

[0033] Next, an embodiment in which region 4 of radio wave lens 100 shown in Fig. 1 is filled with a dielectric will be described. Fig. 5 is an explanatory diagram of yet another embodiment of a radio wave lens of the present invention. Radio wave lens 100B of this embodiment shown in Fig. 5 is composed of a dielectric plate 1 made of a flat dielectric material, a foam plate 7 which is also a flat dielectric material, and a reflector 2 which is arranged parallel to dielectric plate 1 with foam plate 7 interposed therebetween.

[0034] The dielectric plate 1, like the radio wave lenses 100 and 100A, can be selected from low-loss dielectric materials that can be used in general radio wave lenses.

[0035] The foam plate 7 is made of a dielectric material containing air bubbles, and can be selected from, for example, polystyrene foam, polypropylene foam, and the like.

[0036] The reflector 2, like the radio wave lenses 100 and 100A, can be configured as a metal plate or at least a substrate having a surface covered with a metal film, with a reflecting surface 2a arranged parallel to the flat dielectric plate 1. The reflector 2 has a cutout portion 3 where a part is cut out. When the radio wave lens 100B of this embodiment is attached to an antenna device for transmitting or receiving radio waves, the antenna portion of the antenna device, for example a patch antenna, is attached so as to be exposed from the cutout portion 3. At that time, the arrangement, size, etc. of the cutout portion 3 are set according to the shape, etc. of the antenna portion so that the center of the patch antenna and the center of the radio wave lens 100B can be arranged to overlap with each other.

[0037] In this embodiment, the dielectric plate 1 has a thickness t1 shown in FIG. 5, similar to the radio wave lenses 100 and 100A. 2 and 3, the reflected wave 1 generated at the first surface 1a of the dielectric plate 1 and the reflected wave 2 generated at the second surface 1b of the dielectric plate 1 are in phase at the first surface 1a, and the reflected wave 1 and the reflected wave 2 are synthesized to generate a constructive composite wave that is transmitted through the region 4.

[0038] The dielectric plate 1 and the reflector 2 have a distance d1 between a first surface 1a of the dielectric plate 1 facing the reflector 2 and a reflecting surface 2a of the reflector 2 facing the dielectric plate 1, which is the same as that of the radio wave lenses 100 and 100A. TIFF2025070158000013.tif1264. Here, in the radio wave lens 100B of this embodiment, since the region 4 is filled with a dielectric material constituted by the foam plate 7, ε2 is the relative dielectric constant of the foam plate 7. Therefore, the thickness t2 of the foam plate 7 is TIFF2025070158000014.tif1264. Here, ε3 is the relative dielectric constant of the foam board 7. Note that the relative dielectric constant of the foam board 7 can be made approximately equal to the relative dielectric constant of air by appropriately setting the size and density of the air bubbles in the foam board 7. In that case, ε3=1, and t2 is approximately equal to λ0 / 2.

[0039] The dielectric plate 1 and the reflector 2, which are laminated via the foam plate 7 having the thickness t2 set in this way, are arranged in parallel at an interval approximately equal to the thickness of the foam plate 7. Therefore, as described in Figs. 2 and 3, the radio wave incident on the radio wave lens 100B from the power feed point 5 is partially reflected by the dielectric plate 1 and partially radiated from the dielectric plate 1. The reflected wave 1 reflected by the first surface 1a of the dielectric plate 1 and the reflected wave 2 reflected by the second surface 1b of the dielectric plate 1 are in phase at the first surface 1a. As a result, the reflected wave 1 and the reflected wave 2 are synthesized to form a constructive composite wave, which is transmitted through the foam plate 7. The reflected wave 3, which is the composite wave of the reflected wave 1 and the reflected wave 2 that reaches the reflector 2 and is reflected by the reflecting surface 2a, is in phase with the radio wave incident from the power feed point 5 when it transmits through the foam plate 7 and reaches the dielectric plate 1 again. As a result, the reflected wave 3 and the radio wave incident from the feed point 5 reinforce each other at the first surface 1a of the dielectric plate 1, part of which passes through the dielectric plate 1 and is radiated into space, and part of which is transmitted through the foam plate 7 as reflected waves 1 and 2, and is reflected again by the reflecting surface 2a. In this way, the radio wave incident from the feed point 5 spreads in the horizontal direction relative to the surface of the flat dielectric plate 1 by repeated reflection and synthesis, and is radiated in phase into space from the entire second surface 1b of the dielectric plate 1. Therefore, with the radio wave lens 100B as well, narrow directivity and a high antenna gain in the front direction due to that directivity can be obtained.

[0040] The radio wave lens 100B of this embodiment also functions as a radio wave lens for transmission or reception, like the radio wave lenses 100 and 100A.

[0041] The radio wave lenses 100, 100A, and 100B of the present embodiment described above are flat, and the antenna device is directly attached to the notch of the reflector 2, so there is no need to consider the focal length, and it is easy to attach a radio wave lens with the desired characteristics. By appropriately selecting and attaching a radio wave lens with the desired characteristics to an antenna device having an antenna unit with wide directivity, it is easy to make an antenna device according to the required specifications. The directivity of the radio wave lens can be changed depending on the size of the reflector 2. Specifically, by changing the vertical length and horizontal length of the dielectric plate 1 and the reflector 2, it is possible to realize a directivity in which the directivity is wide in the vertical direction where the length is long and the directivity is narrow in the horizontal direction where the length is short.

[0042] (Method of manufacturing radio wave lenses) Next, an embodiment of a method for manufacturing a radio wave lens, which is another aspect of the present invention, will be described. Figures 6 and 7 are explanatory diagrams of an embodiment of a method for manufacturing a radio wave lens, which is another aspect of the present invention, where Figure 6 is an explanatory diagram of a process for forming a laminate, and Figure 7 is an explanatory diagram of a process for singulating the laminate. The method for manufacturing a radio wave lens of this embodiment shown in Figures 6 and 7 is a method for manufacturing a radio wave lens 100B shown in Figure 5.

[0043] First, a dielectric plate 1A, a foam plate 7A and a reflector 2A each large enough to form a plurality of radio wave lenses are prepared.

[0044] The dielectric plate 1A can be selected from low-loss dielectrics that can be used in general radio wave lenses, such as polypropylene resin, acrylonitrile butadiene styrene (ABS) resin, acrylic resin, tetrafluoroethylene resin, polystyrene resin, polycarbonate resin, polybutylene terephthalate resin, polyphenylene resin, Teflon resin, etc. The thickness t1 of the dielectric plate 1A is: TIFF2025070158000015.tif1264, where λ0 is the free space wavelength of the transmitted radio wave, and ε1 is the relative dielectric constant of the dielectric plate 1A.

[0045] The foam plate 7A is made of a dielectric material containing air bubbles, and can be selected from, for example, polystyrene foam, polypropylene foam, etc. The thickness t2 of the foam plate 7A is TIFF2025070158000016.tif1264, where ε3 is the relative dielectric constant of the foam board 7A.

[0046] The reflector 2A is a metal plate or at least a substrate whose surface is covered with a metal film to form a reflective surface, and has a notch 3 through which radio waves pass when the completed radio wave lens is used, at a position that occupies a predetermined area within each individual piece when the radio wave lens is divided into individual pieces.

[0047] The dielectric plate 1A, foam plate 7A and reflector 2A having the above configuration are bonded together to form a laminate 200 as shown in FIG.

[0048] Thereafter, the laminate 200 is cut into individual pieces as shown in Fig. 7. The individual pieces can be cut by a mechanical cutting method or a cutting method using a laser or a water jet.

[0049] In the radio wave lens 100B thus formed, the thickness t1 of the dielectric plate 1 is The result is TIFF2025070158000017.tif1264.

[0050] The dielectric plate 1 and the reflector 2 are arranged such that the distance between the first surface 1a of the dielectric plate 1 facing the reflector 2 and the reflecting surface 2a of the reflector 2 facing the dielectric plate 1 is equal to the thickness t2 of the foam plate 7, The result is TIFF2025070158000018.tif1264.

[0051] In this way, the manufacturing method of the radio wave lens of this embodiment makes it possible to easily manufacture a radio wave lens. In particular, the manufacturing method of the radio wave lens of this embodiment makes it possible to easily change the size of the radio wave lens, and to easily provide radio wave lenses with various antenna characteristics.

[0052] (Antenna device) Next, an embodiment of an antenna device according to another aspect of the present invention will be described. Fig. 8 is an explanatory diagram of an embodiment of an antenna device according to another aspect of the present invention. The antenna device according to this embodiment can be configured to include the radio wave lenses 100, 100A, and 100B described above. The antenna device 300 according to this embodiment shown in Fig. 8 includes the radio wave lens 100B shown in Fig. 5.

[0053] The antenna device 300 of this embodiment is composed of a wireless communication circuit 400 in which an antenna unit 8 is formed on a dielectric substrate, for example, and a radio wave lens 100B. In the example shown in Fig. 8, the antenna unit 8 of the wireless communication circuit 400 is composed of a patch antenna. Note that, although the wireless communication circuit 400 usually has a circuit for performing signal processing formed therein, Fig. 8 illustrates only the antenna unit 8 disposed in the cutout portion 3 of the reflector 2.

[0054] The antenna section 8 is disposed so as to be exposed from the cutout section 3 of the reflector 2 of the radio wave lens 100B, and is disposed so that the center of the antenna section 8 (patch antenna) overlaps with the center of the radio wave lens 100B.

[0055] In the antenna device 300 thus configured, radio waves emitted from the antenna unit 8 are emitted through the radio wave lens 100B, or radio waves incident through the radio wave lens 100B are incident on the antenna unit 8. When radio waves are emitted from the antenna unit 8, as described with reference to Figs. 2 and 3, a part of the radio waves incident on the radio wave lens 100B from the antenna unit 8 is reflected by the dielectric plate 1, and a part of the radio waves is emitted from the dielectric plate 1. The reflected wave 1 reflected by the first surface 1a of the dielectric plate 1 and the reflected wave 2 reflected by the second surface 1b of the dielectric plate 1 are in phase at the first surface 1a. As a result, the reflected wave 1 and the reflected wave 2 are synthesized to form a constructive composite wave, which is transmitted through the foam plate 7. The composite wave of the reflected wave 1 and the reflected wave 2 reaches the reflector 2 and is reflected by the reflecting surface 2a. The reflected wave 3 is in phase with the radio waves incident from the antenna unit 8 when it transmits through the foam plate 7 and reaches the dielectric plate 1 again. As a result, the reflected wave 3 and the radio wave incident from the antenna unit 8 reinforce each other at the first surface 1a of the dielectric plate 1, part of which passes through the dielectric plate 1 and is radiated into space, and part of which is transmitted through the foam plate 7 as reflected waves 1 and 2, and is reflected again by the reflecting surface 2a. In this way, the radio wave incident from the antenna unit 8 is repeatedly reflected and combined, spreading horizontally relative to the surface of the flat dielectric plate 1, and is radiated in phase into space from the entire surface of the second surface 1b of the dielectric plate 1.

[0056] FIG. 9 is a graph showing the output characteristics of the antenna device shown in FIG. 8, and FIG. 10 is a graph showing the output characteristics of the antenna device shown in FIG. 8 in polar coordinates. FIG. 11 is a graph showing the output characteristics of the antenna device without a radio wave lens, and FIG. 12 is a graph showing the output characteristics of the antenna device without a radio wave lens in polar coordinates. FIGS. 9 to 12 show the output characteristics of the antenna characteristics in two planes that are orthogonal to each other in the radiation direction. Comparing the output characteristics shown in FIG. 9 and FIG. 11, the antenna gain in the front direction (angle 0 degrees) of the antenna device with the radio wave lens 100B of this embodiment shown in FIG. 9 is about 11 dB, whereas the antenna gain in the front direction (angle 0 degrees) of the antenna device without the radio wave lens shown in FIG. 11 is about 7 dB. Thus, it was confirmed that the antenna gain of the antenna device of this embodiment is improved by about 4 dB by providing the radio wave lens 100B.

[0057] In addition, when comparing the output characteristics shown in Fig. 10 and Fig. 12, the antenna device with the radio wave lens 100B of this embodiment shown in Fig. 10 has an angle width of about 40 degrees at which the antenna gain drops by 3 dB from the antenna gain in the front direction (angle 0 degrees), while the antenna device without the radio wave lens shown in Fig. 12 has an angle width of about 80 degrees. In addition, when comparing the antenna gain at 90 degrees from the front, the antenna device of this embodiment shown in Fig. 10 has an antenna gain of -10 dB or less, while the antenna device without the radio wave lens shown in Fig. 12 has an antenna gain of -5 dB. Furthermore, as shown in Fig. 10, the antenna device of this embodiment has an antenna gain that drops sharply when it is 30 degrees or more away from the front. In this way, it was confirmed that the antenna device of this embodiment has an improved antenna gain, narrowed directivity, and improved characteristics by providing the radio wave lens 10B.

[0058] When an antenna device with improved characteristics is used as a receiving device, the gain of signals coming from the front of the antenna device is improved, enabling reliable reception. It can also be seen that noise signals coming from directions more than 30 degrees from the front are significantly attenuated, improving the S / N ratio by attenuating noise signals coming from directions other than the desired direction.

[0059] Next, another embodiment of the antenna device according to the present invention will be described. FIG. 13 is an explanatory diagram of another embodiment of the antenna device according to the present invention. In a normal antenna device, a wireless communication circuit having an antenna unit is housed in a case. This case can be made of a dielectric material, and a part of the case can be used as the dielectric plate of the radio wave lens of the present invention. The antenna device 300A according to this embodiment shown in FIG. 13 is an antenna device equipped with the radio wave lens 100B shown in FIG. 5.

[0060] The antenna device 300A of this embodiment is composed of a radio wave lens 100C, a radio communication circuit 9, and a case 10. The radio communication circuit 9 is composed of a dielectric substrate 9A on which an antenna section 8 is formed, a circuit substrate 9B on which a circuit for performing signal processing is formed, and a connector 9C that connects the dielectric substrate 9A and the circuit substrate 9B. The case 10 is composed of a first member 10A and a second member 10B. The radio wave lens 100C is composed of a dielectric plate made of a flat dielectric material, a foam plate 7 which is a flat dielectric material, and a reflector 2 arranged in parallel to the dielectric plate via the foam plate 7.

[0061] Here, the dielectric plate of the radio wave lens 100C of this embodiment is composed of the first member 10A of the case 10. Therefore, the first member 10A can be selected from low-loss dielectric materials that can be used in general radio wave lenses, such as polypropylene resin, acrylonitrile butadiene styrene (ABS) resin, acrylic resin, tetrafluoroethylene resin, polystyrene resin, polycarbonate resin, polybutylene terephthalate resin, polyphenylene resin, Teflon resin, etc.

[0062] The thickness of the first member 10A at least in the portion that functions as the radio wave lens 100C is equal to the thickness t1 of the dielectric plate 1 of the radio wave lens 100B described with reference to FIG. TIFF2025070158000019.tif1264, where λ0 is the free space wavelength of the transmitted radio wave, and ε1 is the relative dielectric constant of the dielectric plate, that is, the first member 10A.

[0063] The configuration and arrangement of the reflector 2 and the foam plate 7 are similar to those of the radio wave lens 100B shown in FIG.

[0064] In this manner, when the dielectric plate constituting the antenna device 300A is made of the dielectric material constituting the case 10, similarly to the above-described antenna device 300, radio waves incident from the antenna section 8 are radiated into space in phase from the surface of the first member 10A of the case 10, which is a flat dielectric material.

[0065] 13, the wireless communication circuit 9 includes a circuit board 9B and a dielectric board 9A on which the antenna unit 8 is formed, but the circuit formed on the circuit board 9B may be formed on the back surface of the dielectric board 9A. In this case, the connector 9C may be formed of a contact hole that penetrates and connects the front and back surfaces of the dielectric board 9A. Alternatively, the circuit board 9B may be disposed on the back surface of the reflector 2.

[0066] The shapes of the first member 10A and the second member 10B of the case 10 can also be changed in various ways, and the shape of the flat plate-like first member 10A shown in Fig. 13 can be made U-shaped (the overall shape is like a tray with a side wall all around) by injection molding or the like in the cross section shown in Fig. 13, and the U-shaped second member 10B can be made flat. Alternatively, both the first member 10A and the second member 10B can be made U-shaped.

[0067] In the antenna device 300A of the present embodiment described above, since the radio wave lens 100C has a flat plate shape, there is no need to consider the focal length when attaching the radio wave lens 100C to the antenna device 300A, and the antenna device 300A can be made thinner. In addition, the dielectric plate of the radio wave lens 100C constitutes a part of the case 10 of the antenna device 300A, so that the number of components constituting the antenna device 300A can be reduced and the weight can be reduced. In particular, when the antenna device 300A of the present embodiment is configured to include the radio wave lens 100A shown in FIG. 4, the number of components constituting the antenna device can be reduced and assembly can be made easier by forming the protrusion corresponding to the spacer 6 integrally with the first member 10A of the case 10. The protrusion corresponding to the spacer 6 can be formed integrally with the first member 10A of the case 10 by injection molding or the like.

[0068] Although the embodiments of the radio wave lens and antenna device of the present invention and the manufacturing method of the radio wave lens have been described above, the present invention is not limited to these. For example, the antenna unit is not limited to a patch antenna, and can be configured as a slot antenna or a waveguide aperture antenna. The antenna unit can also be configured to include either a receiving antenna or a transmitting antenna, or both.

[0069] (summary) (1) One embodiment of a radio wave lens according to the present invention is a radio wave lens including a flat dielectric plate arranged perpendicular to the direction of transmission of radio waves, and a radio wave reflector arranged parallel to the dielectric plate, the dielectric plate having a thickness t1 in the direction of transmission of radio waves of: TIFF2025070158000020.tif1264 (where λ0 is the free space wavelength of the radio wave to be transmitted, and ε1 is the relative dielectric constant of the dielectric plate), and the dielectric plate and the reflector are such that a distance d1 between a first surface of the dielectric plate facing the reflector and a reflecting surface of the reflector facing the dielectric plate is: TIFF2025070158000021.tif1264 (ε2 is the relative dielectric constant of the region between the first surface and the reflective surface), and the reflector is configured to have a notch through which radio waves pass.

[0070] According to the radio wave lens of (1) above, a flat dielectric plate of a specified thickness and a reflector are arranged at a distance shorter than the wavelength of the transmitted radio waves, thereby making it possible to make the radio wave lens thinner and achieving the desired antenna characteristics.

[0071] (2) According to another embodiment, in the radio wave lens of (1) above, the dielectric plate and the reflector are arranged in parallel with an air gap therebetween, and a distance d2 of the air gap between a first surface of the dielectric plate and a reflecting surface of the reflector is d2=λ0 / 2.

[0072] (3) According to another embodiment, in the radio wave lens of (2) above, the dielectric plate and the reflector are supported by a spacer and arranged in parallel, and the height h of the spacer is configured to be h = λ0 / 2.

[0073] (4) According to still another embodiment, in the radio wave lens of (1) above, the dielectric plate and the reflector are arranged in parallel via a flat foam plate, and the foam plate has a thickness t2 in the radio wave transmission direction of: TIFF2025070158000022.tif1264 (ε3 is the relative dielectric constant of the foam board).

[0074] (5) According to one embodiment of a method for producing a radio wave lens, which is another aspect of the present invention, there is provided a method for producing a radio wave lens having a flat dielectric plate arranged perpendicular to the transmission direction of radio waves, the method including the steps of forming a laminate which is an assembly of a plurality of radio wave lenses, in which a dielectric plate, a foam plate, and a reflector are laminated, and singulating the laminate, wherein the singulated radio wave lenses have a thickness t1 of the dielectric plate as follows: TIFF2025070158000023.tif1264 (where λ0 is the free space wavelength of the transmitted radio wave, and ε1 is the relative dielectric constant of the dielectric plate), and the thickness t2 of the foam plate is TIFF2025070158000024.tif1264 (ε3 is the relative dielectric constant of the foam board), and the reflector is configured to have a cutout portion that allows radio waves to pass through and a radio wave reflecting surface.

[0075] According to the manufacturing method of a radio wave lens of (5) above, a laminate is formed in which a dielectric plate, a foam plate, and a reflector are stacked, and the laminate is then singulated to form a radio wave lens, making it possible to manufacture the radio wave lenses with high productivity.

[0076] (6) According to one embodiment of an antenna device which is yet another aspect of the present invention, the antenna device includes a radio wave lens as described in any one of (1) to (4) above, and is configured such that an antenna portion for transmitting and / or receiving radio waves is disposed at a position where the radio waves pass through the cutout portion.

[0077] According to the antenna device of (6) above, by including a thin radio wave lens, it is possible to reduce the thickness of the antenna device and obtain desired antenna characteristics.

[0078] (7) According to another embodiment, in the antenna device of (6) above, the antenna section is configured as a patch antenna.

[0079] (8) According to still another embodiment, in the antenna device of (6) above, the dielectric plate is configured as a part of a case that houses the antenna portion. [Explanation of symbols]

[0080] 100, 100A, 100B, 100C Radio Lens 200 Laminate 300, 300A Antenna Unit 1, 1A Dielectric plate 1a 1st page 1b 2nd side 2, 2A reflector 2a Reflective surface 3 Notch 4 areas 5 Power supply point 6 Spacer 7, 7A Foam board 8 Antenna section 9 Wireless communication circuits 9A Dielectric Substrate 9B Circuit Board 9C Connector 10 Cases 10A First Component 10B Second member

Claims

1. A radio wave lens having a flat dielectric plate arranged perpendicular to the transmission direction of radio waves, a radio wave reflector disposed parallel to the dielectric plate, The dielectric plate has a thickness t1 in the radio wave transmission direction, (λ 0 is the free space wavelength of the transmitted radio wave, and ε1 is the relative dielectric constant of the dielectric plate, The dielectric plate and the reflector are A distance d1 between a first surface of the dielectric plate facing the reflector and a reflecting surface of the reflector facing the dielectric plate is (ε2 is the relative dielectric constant of the region between the first surface and the reflecting surface), The reflector has a notch through which radio waves pass. Radio lens.

2. the dielectric plate and the reflector are arranged in parallel with each other with an air gap therebetween, The distance d2 of the air layer between the first surface of the dielectric plate and the reflecting surface of the reflector is d2=λ 0 / 2 That is, 2. The radio wave lens according to claim 1.

3. the dielectric plate and the reflector are supported by a spacer and arranged in parallel; The height h of the spacer is h=λ 0 / 2 That is, 3. The radio wave lens according to claim 2.

4. the dielectric plate and the reflector are arranged in parallel with each other via a flat foam plate; The foam plate has a thickness t2 in the radio wave transmission direction of: (ε3 is the relative dielectric constant of the foam board), 2. The radio wave lens according to claim 1.

5. A method for manufacturing a radio wave lens having a flat dielectric plate arranged perpendicular to the transmission direction of radio waves, comprising the steps of: A step of forming a laminate which is an assembly of a plurality of radio wave lenses, in which a dielectric plate, a foam plate, and a reflector are laminated; singulating the laminate; Including, The individualized radio wave lens is The thickness t1 of the dielectric plate is (λ 0 is the free space wavelength of the transmitted radio wave, and ε1 is the relative dielectric constant of the dielectric plate), The thickness t2 of the foam plate is (ε3 is the relative dielectric constant of the foam board), The reflector has a notch through which radio waves pass and a surface that reflects radio waves. How radio wave lenses are manufactured.

6. An antenna device comprising the radio wave lens according to any one of claims 1 to 4, An antenna unit for transmitting and / or receiving radio waves is disposed at a position where the radio waves pass through the cutout portion. Antenna device.

7. The antenna unit is a patch antenna.

7. The antenna device according to claim 6.

8. The dielectric plate is a part of a case that houses the antenna unit.

7. The antenna device according to claim 6.

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