JPH0936642A - Co-linear antenna and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antenna with non-directivity and capable of increasing an antenna gain and freely varying length by forming the antenna with a coaxial core shape feed wire in which dielectric coating is applied to a conductor and a coaxial sheath shape antenna element constituted by providing a dielectric layer on the surface of a dielectric partially. SOLUTION: This antenna is constituted of the oaxial core shape feed wire 1, the coaxial sheath shape antenna element 2, a dielectric spacer 3, a connector 4 and a radome 5. The feed wire 1 is formed by applying the dielectric coating 1b to the conductor 1a. While, the length of the dielectric coating 1b is decided by its dielectric constant. In this connection, when the dielectric constant is low, the length is increased, and the antenna gain is increased. On the other hand, when the dielectric constant is high, the length is shortened, and the antenna gain is decreased, however, merit to make an antenna itself compact is obtained. In this regard, the dielectric constant is adjusted corresponding to required characteristic.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a collinear antenna which is omnidirectional and has a large antenna gain, and a method for manufacturing the same.

[0002]

2. Description of the Related Art As disclosed in Japanese Utility Model Application Laid-Open No. 2-5908, a conventionally proposed antenna is of a type in which a feed line and a radiating element are separately formed on the front and back of a printed circuit board, and Japanese Patent Laid-Open No. Sho 64-64. -78004 and JP-A-6-303
As disclosed in Japanese Patent No. 031, there is known a type in which a radiating element is formed in a tubular shape with a metal foil or a metal tube, and a feeder line is arranged at the center.

[0003]

The former type of the above-mentioned proposals has a simple structure / structure, but has a Teflon substrate (Teflon is a trade name) on the substrate due to the dielectric constant.
However, there is a problem in that the cost of parts is very high, and it is necessary to use an interposition to fix the radome in a straight line while keeping it straight. Was. Further, the former example has a drawback that the dimensions such as the entire length and the length of the element portion cannot be changed because the dielectric constant of the substrate cannot be freely set.

On the other hand, in the latter type, a metal foil or a metal tube has to be processed into a complicated sleeve shape, the processing cost is very high, and it is required in terms of electric characteristics to maintain the shape. As described above, there are problems that the thick foil and the tube are used and the weight is heavy, and that the number of components is large and the component cost and the assembly cost are high.

The present invention solves the above two problems,
It is an object of the present invention to provide a collinear antenna that is omnidirectional, has a large antenna gain, is inexpensive, is simple, and can change the length considerably freely as needed, and a method for manufacturing the same.

[0006]

A collinear antenna provided by the present invention comprises a coaxial core-shaped feed line formed by applying a dielectric coating on a conductor, and a conductive layer partially provided on the surface of the dielectric. A coaxial sheath antenna element configured,
A connector attached to an antenna main body composed of these feeders and antenna elements, and an insulating radome as an outermost layer are further provided.

The number of antenna elements may be one, but it is preferable that the number of antenna elements is two or more and they are connected in a comb-like shape with the feeder line as a core and in a daisy chain shape through a dielectric spacer. Such a dielectric spacer may be in the shape of a ring, and in addition, the outer diameter may be made larger than that of the antenna element to add a function of supporting the insulating radome from the inside, or a step or a step which can be coupled to the antenna element. It may have a key groove. There are various types of connectors, but it is preferable to use a plastic molded product into which a metal terminal is inserted.

A method of manufacturing a collinear antenna provided by the present invention is a method of manufacturing a collinear antenna including a coaxial core-shaped feed line and a coaxial sheath-shaped antenna element, wherein the feed line is a dielectric on a conductor. The coating is formed by extrusion molding or injection molding, and the antenna element is a method of forming a conductive layer on a plastic molded product by plating.

Although various manufacturing methods can be considered for the antenna element, for ease of manufacturing, the antenna element is manufactured by a two-shot molding method using an easily plating resin and a difficult plating resin.
Alternatively, it can be obtained by a method in which a dielectric is manufactured by a one-shot molding method of an easily plating resin and a conductive layer pattern is formed by a masking method. Further, the number of antenna elements may be one, but preferably two or more, and it is preferable to assemble them by connecting them in a daisy chain shape through a ring-shaped dielectric spacer.

The dielectric spacer may be manufactured by injection molding, or punching and cutting.

When a connector is attached to the antenna body composed of the feeder and the antenna element and an insulating radome is formed as the outermost layer, an insulating material is collectively injection-molded to the antenna body and the connector. A method of integration can be obtained.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a preferred embodiment of a collinear antenna according to the present invention, in which 1 is a coaxial core feed line, 2 is a coaxial sheath antenna element, 3 is a dielectric spacer, and 4 is a dielectric spacer. The connectors 5 are radomes.

The feed line 1 is formed by applying a dielectric coating 1b on the conductor 1a as shown in (c). The conductor 1a is, for example, a rod-shaped one made of copper, iron, or an alloy thereof, and the surface thereof may be plated with copper or the like. The conductor 1a is preferably rigid in view of the properties of the antenna. Considering this point, in the case of copper, a hard copper wire is preferable.

On the other hand, the length of the dielectric coating 1b is determined by its dielectric constant. By the way, when the permittivity is low, the length becomes long and the antenna gain can be increased. On the other hand, when the dielectric constant is high, the length can be shortened, and although the antenna gain is reduced, there is an advantage that the antenna itself can be made compact. From these points, the dielectric constant can be adjusted according to the required characteristics. As the dielectric coating 1b, generally, a fluorine resin having a low dielectric constant or an olefin resin such as polyethylene is used, but other plastics may be used without particular preference. Further, in order to adjust the dielectric constant, it is possible to use a mixture of inorganic fillers such as zinc white, titanium white, and calcium carbonate.

As a method of forming the dielectric coating 1b on the conductor 1a, extrusion molding and injection molding are suitable. According to extrusion molding, a long product can be continuously molded at one time, and the length can be adjusted by cutting the product as necessary, which is suitable for changing specifications and manufacturing a large number of small-lot products. On the other hand, the injection molding has a merit that the processing of the terminal can be omitted because the molding is performed one by one, and various types can be manufactured and selectively used according to the specifications and materials of the antenna.

In the antenna element 2, as shown in (a), the conductive layer 2 is formed on the surface of the pipe-shaped dielectric resin molded product 2a.
b is formed in a three-dimensional pattern by plating or the like, and a resin-molded product that is easy to plate, that is, an easily-platable resin is suitable. For this purpose, for example, ABS resin, polycarbonate, PET, PBT, nylon resin and the like are suitable materials. When soldering is required, liquid crystal polymer, polyester imide, polysulfone, polyether sulfone, polyphenylene sulfide and other super engineering plastics, and epoxy resin, phenol resin and other thermosetting resins are suitable materials. . Further, a filler such as glass fiber, potassium titanate fiber or calcium carbonate may be added to the above resin. This filler also serves to adjust the dielectric constant of the resin and is important in a sense.

A combination of an easily-plated resin and a hardly-plated resin may be integrated. In this case, the easy-plating resin is used only in the portion 2b where the conductive layer is formed by plating, and the difficult-plating resin is used in the portion 2a which becomes the non-conductive portion. As the plating-resistant resin, a material that is relatively difficult to plate as compared with the plating-friendly resin,
It does not mean in any case what makes plating difficult or impossible. Therefore, as its material,
It can be selected from various materials as the above-mentioned easily-platable resin. An injection molding method is generally used as a molding method, but a long pipe may be formed by extrusion molding.
In this case, it can be cut later according to the required length, and like the feeder line, it is suitable for specification changes and small-lot production.

The method of forming the conductive layer on the easily-platable resin includes plating, vapor deposition, sputtering, and conductive paint, and any method may be used, but generally plating with copper, nickel or the like is common.

The method of forming a plating on a specific pattern is roughly classified into the following two methods. One is an exposure method in which a one-shot molded product, which is molded entirely of an easily-platable resin, is used and patterning is performed using an etching resist or a plating resist. The other is a method of using a two-shot molded product made of a combination of such an easily plating resin and a difficult plating resin.

The antenna element manufactured by the above method is divided into two or more pieces, and is provided in the form of a coaxial sheath on the feed line 1 in such a manner that they are connected in series via the dielectric spacer 3 in the form of a ring. Is desirable. In this embodiment, as shown in (c), the antenna element 2, which is a short product having a predetermined length,
2 ′, 2 ″ ″, 2 ″ ″ are skewered with the feeder line 1 as a core, and dielectric spacers 3a, 3a ′, 3a ″ ″, 3
The antennas are continuously arranged in a daisy chain via a ″ ″, thereby forming a main body of a desired antenna.

The dielectric spacer 3 may be any as long as it has a dielectric constant satisfying the characteristics of the antenna, but it can be selected from the various dielectrics of the above-mentioned easily-platable resin, and the concrete shape is as shown in FIG. In addition to 4 (a) of the sliced body 3a, a radome 5 having a large outer diameter as shown in (b) will be described later.
It may also be used as a support member from the inside of the above, or may have a step or a key groove as shown in (c) and (d) to ensure coupling with the pipe-shaped antenna element. These are generally formed by injection molding, but may be formed by punching or cutting.

As the antenna element, a dielectric,
For the dielectric as the spacer, not only the resin as described above but also an inorganic material such as ceramic may be used depending on the case.

Further, the connector 4 has a metal terminal built in a sheath-shaped body, and one end of the antenna element 2 and the feed line 1 is inserted as shown in FIG. 2 and FIG. A metal terminal is brought into contact with the conductor 1a or the like and is brought into contact with the antenna element 2 through an appropriate inclusion to form an antenna connector. The connector 4 has a role of mechanically connecting and holding in addition to electrically connecting to an external device. Also,
When installed outdoors, it is required to have sufficient mechanical strength to withstand the effects of external forces such as wind, vibration and impact. For this reason, a metal product is generally used, but if the influence thereof is small, it is better to use a plastic molded product in which the conductive portion is integrally molded.

The radome, which is the outermost layer, is as shown by reference numeral 5 in FIG. 1 (d), and is composed of a tubular body 5a made of an insulating material and an insulating material fitted on one end side of the body. The other end (non-connector portion) of the antenna assembly, which is composed of the cap 5b, is assembled from the cut end on the other end side as shown in FIG. The outer cover is constructed so as to be housed in the sheath of the antenna and integrally coupled by screwing or the like, thereby protecting the antenna structure from external force. When installed outdoors, heat resistance is also required. FRP is generally used to satisfy these requirements, but an insulator is not a particular choice.

2 and 3 show a completed collinear antenna assembled in the above-described manner.
The dielectric spacer 3b in this embodiment is of a type having a large outer diameter, and also has a function of supporting the radome body 5a from the inside.

Specific examples will be given below. These specific examples are
It was embodied from the viewpoint of ease of implementation even if you get tired of it,
It is not intended to be limiting.

Example 1 FIGS. 1 and 2 (FIG. 3) were adopted as the antenna structure. For the power supply line 1, a hard copper wire was used for the conductor 1a, and a long product extruded and coated with polyethylene having a dielectric constant of 2.3 was cut into a predetermined length, and the conductor was exposed at the end. Antenna elements 2, 2 ', 2 ",
2 ″ ″ and 2 ″ ″ are made into a two-shot molded product using a liquid crystal polymer as the easily-plated resin 2a and polyphenylene sulfide as the hard-to-plate resin 2b, and electroless copper plating is applied to a thickness of 15 μm. For rust prevention, an electroless nickel plating having a thickness of 1 μm was used.
Liquid crystal polymer is used for the dielectric spacer by injection molding.
Using the shape of (C), the connection between the antenna elements was strengthened. The connector 4 is made of brass and has a nickel-plated surface. The radome 5 used was one in which one end of the FRP pipe 5a was covered with a cap made of FRP. According to the collinear antenna of the present embodiment, it is possible to obtain a non-directional characteristic with no practical problem and a large antenna gain. In the structure of this embodiment, each component can be easily manufactured and the length can be freely determined.

Example 2 FIGS. 1 and 2 (FIG. 3) were adopted as the antenna structure. For the power supply line 1, a copper-plated steel wire is used for the conductor 1a, and polypropylene having a dielectric constant of 2.6 is coated by injection molding. Further, the antenna element 2 is a one-shot molded product made of ABS resin, which is electroplated with copper. 8 μm was applied and a conductive layer pattern was formed by etching with an etching resist. As the dielectric spacer, a Teflon sheet punched into the shape of 3a in FIG. 4 (a) was used. Others were the same as in Example 1. Also in this embodiment, the antenna characteristics comparable to those of the first embodiment could be obtained.

[0029]

According to the present invention as described above, there is provided a collinear antenna that is omnidirectional, has a large antenna gain, is inexpensive, is simple, and can change its length considerably as needed, and a manufacturing method thereof. The intended purpose of doing so is achieved, and various customer uses relating to antenna characteristics, size, etc. can be easily dealt with, and in addition to the cost of each component, the assembly cost can be reduced and the cost can be reduced.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention, in which (a) is an explanatory view of parts such as an antenna element and a connector, (b) is an explanatory view of a feeder line, and (c) is an explanation of an assembled state of the antenna element and a connector. Figure, (d) is an illustration of the radome.

FIG. 2 is an explanatory longitudinal sectional view of a collinear antenna in a completed state, showing an embodiment of the present invention.

FIG. 3 shows an embodiment of the present invention, in which (a) is a cross-sectional view of a main part of the completed collinear antenna, and (b) is an end view of the collinear antenna on the connector side.

FIG. 4 shows an embodiment of the present invention, in which (a), (b) and (c)
(D) A perspective view of a specific example of both dielectric spacers.

[Explanation of symbols]

1 Feed line 1a Conductor 1b Dielectric coating 2, 2 ', 2 ", 2'", 2 "" Antenna element 2a Conductive part; Easy plating resin 2b Non-conductive part; Hard plating resin 3, 3a, 3a, 3a , 3a, 3c, 3d Dielectric spacer 4 Connector 5 Radome 5a Insulating pipe 5b Insulating cap

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiyuki Takano 5-1-1 Hidakacho, Hitachi City, Ibaraki Prefecture Hitachi Cable Co., Ltd. Hidaka Plant

Claims (12)

[Claims] 1. A coaxial core feed line formed by applying a dielectric coating on a conductor, a coaxial sheath antenna element formed by partially providing a conductive layer on the surface of a dielectric, and these feed lines. A collinear antenna comprising a connector attached to an antenna main body composed of an antenna element, and an insulating radome as an outermost layer. 2. The collinear antenna according to claim 1, wherein the number of the antenna elements is two or more, and the antenna elements are connected in a comb shape with the feeder line as a core and in a daisy chain shape via a dielectric spacer. 3. The collinear antenna according to claim 2, wherein the dielectric spacer has an outer diameter larger than that of the antenna element and can support the insulating radome from the inside. 4. The dielectric spacer has a step or a key groove that can be coupled to an antenna element.
The collinear antenna according to claim 2. 5. The collinear antenna according to claim 1, wherein the connector is a plastic molded product into which a metal terminal is inserted. 6. A method for manufacturing a collinear antenna comprising a coaxial core-shaped feed line and a coaxial sheath-shaped antenna element, wherein the feed line is formed by extrusion molding or injection molding a dielectric coating on a conductor. The antenna element is a collinear antenna manufacturing method, in which a conductive layer is formed on a plastic molded product by plating. 7. The method of manufacturing a collinear antenna according to claim 6, wherein the antenna element is manufactured by a two-shot molding method using an easily plating resin and a difficult plating resin. 8. The method of manufacturing a collinear antenna according to claim 6, wherein the antenna element is made of a dielectric material by a one-shot molding method of an easily plating resin and a conductive layer pattern is formed by a masking method. 9. The method for manufacturing a collinear antenna according to claim 6, wherein the number of the antenna elements is two or more, and the antenna elements are connected in a daisy chain shape through a dielectric spacer in a ring shape. 10. The method of manufacturing a collinear antenna according to claim 9, wherein the dielectric spacer is manufactured by an injection molding method. 11. The method for manufacturing a collinear antenna according to claim 9, wherein the dielectric spacer is manufactured by punching and cutting. 12. A connector is attached to an antenna body composed of the feed line and an antenna element, and an insulating radome is formed as an outermost layer. The insulating radome is made of an insulating material with respect to the antenna body and the connector. 7. The method for manufacturing a collinear antenna according to claim 6, wherein the components are collectively injection-molded and integrated.