JP2005020526A - Planar slot antenna and metal mold for casting its antenna base part - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure plane roughness and electric characteristics by enabling a casting to be easily extracted from a metal mold. <P>SOLUTION: A planar slot antenna has an antenna base part 100 and a slit board 200a. The antenna base part 100 is formed by mold and provided with a waveguide 110 including a bottom surface 111 which extends in parallel with a radio wave transmitting/receiving surface, both side wall surfaces 112 which rise while being connected with both sides of the bottom surface and extend facing each other so as to sandwich the bottom surface and a termination wall surface 113 which rises while being connected with a termination part of the bottom surface 111 and is also connected with both side wall surfaces 112. In the slit board 200, a plurality of slits 210 are arranged and formed at a part corresponding to the waveguide of the antenna base part, and the slit board 200 is fixed to the antenna base part 100. An angle formed between the bottom surface 111 and the termination wall surface 113 of the waveguide 110 of the antenna base part is set to be 90 degrees plus 3 to 5 degrees and the radius of curvature of a boundary part between the bottom surface 111 and both side wall surfaces 112 and the termination wall surface 113 is set to be 0.5 to 2 mm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a planar slot antenna and a mold for casting an antenna base thereof, and more particularly, an antenna base portion formed on a surface of a radio wave transmission / reception side with a waveguide disposed in parallel with the surface, It belongs to a planar slot antenna having a plurality of slits arranged in a portion corresponding to the waveguide of the antenna base portion and fixed to the antenna base portion, and a mold for casting the antenna base portion.
[0002]
[Prior art]
A conventional planar slot antenna of this type will be described with reference to the drawings. FIG. 3 is an exploded perspective view showing an example of a conventional flat slot antenna, and FIGS. 4A and 4B are a perspective view and a partially enlarged perspective view of the waveguide type antenna base portion.
The planar slot antenna includes a waveguide type antenna base portion 100x in which a plurality of waveguides 110x are arranged in parallel with each other on the surface on the radio wave transmission / reception side, and a plurality of the waveguide type antenna base portions 100x. A plurality of slits 210 and termination slits 220x are arranged in portions corresponding to the respective waveguides 110x, and a slit plate 200x fixed to the waveguide antenna base 100x with a plurality of set screws 300; The details of each of the waveguides 110x of the waveguide type antenna base 100x are as follows.
[0003]
These waveguides 110x rise from a bottom surface 111x extending in parallel to the radio wave transmission / reception surface, and both sides of the bottom surface 111x, and extend opposite to each other so as to sandwich the bottom surface 111x (one side in FIG. 4). ), A terminal wall surface 113x that rises up and connects to the end portion of the bottom surface 111x, and that also connects to the two side wall surfaces 112x, and includes the bottom surface 111x, the two side wall surfaces 112x, and the terminal end The boundary with the wall surface 113x is a bottom boundary line 114x.
[0004]
The waveguide antenna base portion 100x is cast by a fixed mold and a movable mold, but the surface on the radio wave transmission / reception side has a complicated shape, so that the frictional resistance increases. In such a case, it is common to use this surface side as a movable mold and attach an extrusion pin for taking out the casting from the mold, but the trace of the extrusion pin is attached to the surface as irregularities. However, since the surface of the waveguide serving as a path for radio waves is strictly required to have a flat surface, such irregularities are not allowed. Therefore, the radio wave transmission / reception side is a fixed type and the back side thereof is a movable type.
[0005]
When the waveguide type antenna base 100x (hereinafter also referred to as a casting) is cast with such a mold, the molten metal injected into the mold is shrunk when solidified, and the casting remains in the fixed mold as a defective product. In addition, because it becomes difficult to remove the casting from the mold due to shrinkage, it is difficult to remove the casting from the mold due to the shrinkage. Usually, a draft of about 1 to 1.5 degrees is provided (for example, see Non-Patent Document 1).
[0006]
[Non-Patent Document 1]
Nobuyuki Ota, “Die Cast”, Nikkan Kogyo Shimbun, p. 213-214
[0007]
Accordingly, the angles ∠α and ∠β between the side wall surfaces 112x and the end wall surface 113x of the waveguide antenna base portion 100x waveguide 110x and the bottom surface 111x are also about 90 degrees plus about 1 to 1.5 degrees. .
[0008]
[Problems to be solved by the invention]
The conventional planar slot antenna described above has a waveguide antenna base 100x and a slit plate 200x, and a plurality of waveguides 110x are arranged and formed in parallel with each other in the waveguide antenna base 100x. Each of the waveguides 110x includes a bottom surface 111x, and both side wall surfaces 112x and a termination wall surface 113x that are connected to and rise from the bottom surface 111x, and the waveguide type antenna base portion 100x is formed as a mold. When the mold is formed, the molten metal poured into the mold (mold) shrinks as it solidifies, and the casting tends to remain in the mold, and it is difficult to remove the casting from the mold. The surface of the mold that forms both the side wall surfaces 112x and the end wall surface 113x of the waveguide 110x has a draft angle of about 1 to 1.5 degrees. , Waveguide 110x, both sidewall surfaces 112x and a terminal wall 113x is the angle formed between the bottom surface, which is approximately 90 degrees plus 1 to 1.5 degrees.
[0009]
However, since the amount of contraction in the longitudinal direction of the waveguide 110x is larger than between the side wall surfaces 112x, the frictional resistance is large at this draft, and there is a high risk of casting remaining in the mold. There is a problem in that it becomes difficult to remove the casting, and it becomes impossible to ensure the definition of the flatness and the electrical characteristics are deteriorated.
[0010]
The object of the present invention is to reduce the frictional resistance between the mold and the casting, reduce the risk of the casting remaining in the mold, and make it easy to extract the casting from the mold in view of the above problems of the prior art. It is an object of the present invention to provide a planar slot antenna and a mold for casting the antenna base part, which can ensure the flatness and can obtain good electrical characteristics.
[0011]
[Means for Solving the Problems]
The technical means of the present invention for achieving the above object has the following configuration.
A planar slot antenna according to a first aspect of the present invention is a planar slot antenna having one surface as a radio wave transmission / reception surface. The bottom surface extends parallel to the radio wave transmission / reception surface, and is connected to both sides of the bottom surface and rises. An antenna base portion that is molded with a waveguide including both side wall surfaces extending opposite to each other so as to be sandwiched, and a termination wall surface that is connected to and rises to a terminal portion of the bottom surface, and is also connected to the both wall surfaces;
A slit plate in which a plurality of slits are arranged and fixed to the antenna base portion in a portion corresponding to the waveguide of the antenna base portion,
Comprising
In the waveguide of the antenna base portion, the angle formed between the bottom surface and the end wall surface is 90 degrees plus 3 to 5 degrees larger than the angle formed between the bottom surface and both side wall surfaces,
The radius of curvature of the boundary portion between the bottom surface, both side wall surfaces, and the terminal wall surface was set to 0.5 to 2 mm.
It is characterized by that.
[0012]
Further, the antenna base portion is formed by a plurality of waveguides formed in parallel with each other so that the bottom surfaces thereof are aligned on the same plane,
The slit plate has a configuration in which a plurality of slits are arranged and formed at portions corresponding to the plurality of waveguides of the antenna base portion.
[0013]
An antenna base portion casting mold for a planar slot antenna according to a second aspect of the invention is an antenna base portion casting mold for the planar slot antenna,
The draft angle of the wall surface corresponding to the terminal wall surface of the antenna base portion waveguide is 3 to 5 degrees,
The antenna base portion has a configuration in which the radius of curvature of the portion corresponding to the boundary line between the bottom surface, both side wall surfaces, and the terminal wall surface is 0.5 to 2 mm.
[0014]
Further, the antenna base part casting mold is formed by coating the surface forming the antenna base part with a low friction member.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
In one embodiment of the planar slot antenna and the antenna base casting mold thereof according to the present invention, the planar slot antenna is
A planar slot antenna having one surface as a radio wave transmission / reception surface, a bottom surface extending in parallel to the radio wave transmission / reception surface, rising on both sides of the bottom surface and extending opposite to each other so as to sandwich the bottom surface And an antenna base portion that is molded with a waveguide including a termination wall surface that is connected to and rises from the terminal portion of the bottom surface and that is also connected to the both side wall surfaces;
A slit plate in which a plurality of slits are arranged and fixed to the antenna base portion in a portion corresponding to the waveguide of the antenna base portion;
Comprising
In the waveguide of the antenna base part, the angle formed between the bottom surface and the end wall surface is 90 degrees plus 3 to 5 degrees larger than the angle formed between the bottom surface and both side wall surfaces,
It has a configuration and structure in which the radius of curvature of the boundary line between the bottom surface, both side wall surfaces, and the terminal wall surface is 0.5 to 2 mm.
[0016]
In the planar slot antenna in this embodiment, the angle that the antenna base portion forms with the bottom surface of the termination wall surface that is the end portion in the longitudinal direction of the waveguide is the angle between the both wall surfaces and the bottom surface (usually 90 degrees plus 1 to 90 degrees plus 3 to 5 degrees, which is greater than about 1.5 degrees), and the boundary line between the bottom surface, the end wall surface, and both side wall surfaces is usually in a state where the two surfaces are simply butted. The mold is formed by rounding so as to have a curvature radius of 5 to 2 mm. Therefore, the antenna base part casting mold for forming the antenna base part also has the antenna base part like this. Naturally, the end wall surface portion has a draft of 3 to 5 degrees in order to obtain a simple structure and shape, and the curvature is about 0.5 to 2 mm at the boundary line portion between the bottom surface, the end wall surface, and both side wall surfaces. Have a radius So, it is rounded.
[0017]
Therefore, by forming the antenna base part with the antenna base part casting mold, even if the shrinkage of the hot water injected into the mold increases in the longitudinal direction of the waveguide, the mold on the end wall surface part・ The frictional resistance between castings and the frictional resistance at the boundary between the waveguide bottom and other wall surfaces can be reduced, reducing the risk of casting remaining in the mold, and removing the casting from the mold. At the same time as the extraction, it is possible to ensure the flatness within the set value and to obtain good electrical characteristics.
[0018]
【Example】
Next, embodiments of the present invention will be described with reference to the drawings.
FIGS. 1A and 1B are a perspective view and a partially enlarged perspective view of a waveguide type antenna base portion of an embodiment of the planar slot antenna of the present invention, and FIG. It is a disassembled perspective view which shows the relationship between a slit plate.
The planar slot antenna of this embodiment has a waveguide type antenna base 100 and a slit plate 200, the details of which are as follows.
[0019]
First, the waveguide type antenna base unit 100 rises on a surface on the radio wave transmission / reception side so as to extend parallel to the radio wave transmission / reception surface and to both sides of the bottom surface 111 so as to sandwich the bottom surface 111 therebetween. Both side wall surfaces 112 extending in opposition to each other (one of which is not visible in FIG. 1, a broken line portion at the tip of an arrow), and a termination wall surface 113 that is connected to the end portion of the bottom surface 111 and that is connected to both side wall surfaces 112. A plurality of waveguides 110 are formed, and their bottom surfaces 111 are arranged in parallel with each other in the same plane. In these waveguides 110, the angle 両 側 A formed by the bottom surface 111 and both side wall surfaces 112 is the same as in the conventional example. The angle ∠B formed by the bottom surface 111 and the end wall surface 113 is 90 degrees plus 3 to 5 degrees, which is larger than 90 degrees plus 1 to 1.5 degrees. In addition, the boundary line portion between the bottom surface 111 and both side wall surfaces 112 and the end wall surface 113 has a radius of curvature R of about 0.5 to 2 mm, and includes a fixed type and a movable type having the bottom surface 111 as a dividing surface. It is cast by a mold.
[0020]
On the surface of the waveguide type antenna base portion 100 on the side where the waveguide 110 is disposed, a plurality of slits 210 are provided in a portion corresponding to each waveguide 110, and an oval termination is provided in a portion corresponding to the termination wall surface 113. The slit plate 200 formed with the slits 220 is screwed and fixed by a plurality of set screws 300.
[0021]
As described above, the waveguide-type antenna base unit 100 is cast by a mold composed of a fixed mold and a movable mold, and this antenna base casting mold (hereinafter also simply referred to as a mold) is illustrated. Although omitted, as a matter of course, in order to obtain the above-described structure and shape, the plurality of waveguide 110 forming portions of the waveguide type antenna base portion 100 are removed by 3 to 5 degrees on the wall surface forming the terminal wall surface 113. In addition, the boundary portion (bottom boundary line 114 portion) between the bottom surface 111 and both side wall surfaces 112 and the end wall surface 113 is rounded so as to have a radius of curvature of about 0.5 to 2 mm. ing.
[0022]
Therefore, the waveguide type antenna base portion 100 cast with such an antenna base portion casting mold usually has a large contraction amount in the longitudinal direction of the waveguide 110 during casting. Even if the amount of shrinkage in the direction is larger than the others, the draft angle of the end wall surface 113 is large, so that the frictional resistance between the mold and the casting in this part can be reduced, and the bottom surface 111 and the end wall 113 and Since the boundary part (114) with both side wall surfaces 112 is rounded, the frictional resistance between the mold and the casting can be reduced in the part where the waveguide 110 is formed. The risk that a part of the tube-type antenna base 100 remains may be reduced, and the casting (100) can be easily extracted from the mold, so that the flatness of each surface forming the waveguide 110 is regulated. Can be secured in the value, it is possible to obtain satisfactory electrical properties.
[0023]
In addition, by increasing the angle 終端 B formed by the end wall surface 113 with the bottom surface 111 from 3 to 5 degrees from 1 to 1.5 degrees in the conventional example, the electrical characteristics such as directivity may be affected. . In such a case, the shape, size, arrangement position, etc. of the slit plate 200 corresponding to the end wall surface 113 of the slit plate 200 are adjusted, and the electrical connection between the waveguide 110 and the end wall surface 113 is adjusted. Matching can be performed to ensure preset electrical characteristics. If the angle ∠B is larger than 5 degrees, the frictional resistance is reduced and the mold can be easily pulled out from the mold, that is, the releasability is improved, but can be set by adjusting the shape, size, arrangement position, etc. of the terminal slit 220. Since there is a high possibility that the obtained electrical characteristics cannot be obtained, the upper limit is set to 5 degrees. The same applies to the radius of curvature of the bottom boundary line 114 portion.
[0024]
In the waveguide type antenna base casting mold for the planar slot antenna in this embodiment, when the surface of the waveguide type antenna base 100 is coated with a low friction member such as titanium, the space between the mold and the casting is reduced. It is possible to further improve the mold releasability.
[0025]
【The invention's effect】
As described above, according to the present invention, the angle between the bottom surface and the end wall surface of the waveguide of the antenna base portion is 90 degrees plus 3 to 5 degrees, and the curvature of the boundary line portion between the bottom surface, both side wall surfaces, and the end wall surface is set. The radius is set to 0.5 to 2 mm, and the angle of the bottom surface and the end wall surface forming portion, and the bottom surface forming portion and both side wall surfaces and the terminal end of the mold for casting the antenna base so that such a structure can be formed. By setting the radius of curvature of the boundary line portion with the wall surface forming portion to the above value, even when the shrinkage amount of hot water when casting the antenna base portion is increased particularly in the longitudinal direction of the waveguide, The frictional resistance with the mold can be reduced, the risk of casting remaining in the mold can be reduced, and the casting can be easily extracted from the mold. Can be secured within the Is able to obtain good electrical properties, there is an effect that.
[Brief description of the drawings]
FIG. 1 is an overall perspective view and a partially enlarged perspective view of a waveguide antenna base portion of a planar slot antenna according to an embodiment of the present invention.
FIG. 2 is an exploded perspective view of a planar slot antenna including the waveguide type antenna base shown in FIG.
FIG. 3 is an exploded perspective view showing an example of a conventional planar slot antenna.
4 is a perspective view of an entire waveguide type antenna base portion of the planar slot antenna shown in FIG. 3, and a partially enlarged perspective view thereof. FIG.
[Explanation of symbols]
100, 100x Waveguide type antenna base 110, 110x Waveguide 111, 111x Bottom surface 112, 112x Side wall surface 113, 113x Termination wall surface 114, 114x Bottom boundary line 120 Screw hole 200, 200x Slit plate 210 Slit 220, 220x Termination slit 230 Screw hole 300 Set screw

Claims (4)

A planar slot antenna having one surface as a radio wave transmission / reception surface, a bottom surface extending in parallel to the radio wave transmission / reception surface, rising on both sides of the bottom surface and extending opposite to each other so as to sandwich the bottom surface And an antenna base portion that is formed with a waveguide including a termination wall surface that is connected to and rises from the bottom end portion of the bottom surface and that is also connected to the both side wall surfaces;
A slit plate in which a plurality of slits are arranged and fixed to the antenna base portion in a portion corresponding to the waveguide of the antenna base portion,
Comprising
In the waveguide of the antenna base portion, the angle formed between the bottom surface and the end wall surface is 90 degrees plus 3 to 5 degrees larger than the angle formed between the bottom surface and both side wall surfaces,
The radius of curvature of the boundary portion between the bottom surface, both side wall surfaces, and the terminal wall surface was set to 0.5 to 2 mm.
A planar slot antenna. The antenna base portion is formed by forming a plurality of waveguides parallel to each other so that the bottom surfaces thereof are aligned on the same plane,
The slit plate is formed by arranging a plurality of slits in portions corresponding to the plurality of waveguides of the antenna base part,
The planar slot antenna according to claim 1. A mold for casting the antenna base portion of the planar slot antenna according to claim 1 or 2,
The draft angle of the wall surface corresponding to the terminal wall surface of the antenna base portion waveguide is 3 to 5 degrees,
The radius of curvature of the portion corresponding to the boundary line between the bottom surface of the antenna base portion waveguide and both side wall surfaces and the terminal wall surface is set to 0.5 to 2 mm.
Mold for casting antenna base of flat slot antenna. 4. The mold for casting an antenna base part of a planar slot antenna according to claim 3, wherein a low friction member is coated on a surface of the antenna base part casting mold that forms the antenna base part.

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