JPH04572Y2 - - Google Patents

Description

[Detailed Description of the Invention] a. Field of Industrial Application The present invention relates to a grounding wire used in medium wave or long wave transmission antennas.

b. Prior Art Conventionally, as this type of grounding wire, a bare copper wire or a wire formed by connecting a copper plate or the like to a bare copper wire has been used.

c Problems to be solved by the invention For grounded antennas used for medium wave or long wave transmission, it is desirable to minimize the grounding resistance in order to increase radiation efficiency.
For this reason, a grounding method has conventionally been adopted in which a large number of bare copper wires connected in a radial or mesh pattern around the antenna are buried in the ground. However, the length of each grounding wire used for ultra-long wave transmission is up to 1,000m, and the buried range extends to agricultural land or afforestation land adjacent to the transmitting facility. This is not uncommon.
Grounding wires buried outside the area of the transmitting facility could be cut by farming operations or stolen, resulting in increased grounding resistance and a decrease in the radiation efficiency of the antenna.

However, since the above-mentioned conventional grounding wire is simply a bare wire buried underground, it is very difficult to detect whether or not the wire is broken.

The present invention has been devised in view of the problems of the prior art described above, and its purpose is to provide a grounding wire for an antenna that can easily detect the presence or absence of a disconnection.

d Means for Solving the Problems The present invention for solving the above problems consists of a layer made of an insulating material covering a conductive core wire, and a conductive surface covering the layer made of the insulating material. The core wire and the surface layer are short-circuited at one end face to form one circuit, and the surface layer is connected to an antenna at the other end face.

e Effect When connecting a DC resistance measuring device between the core wire and the surface layer at the end surface opposite to the end surface where the core wire and the surface layer are short-circuited, a closed circuit formed by the core wire and the surface layer is connected. Direct current flows. The core wire and the surface layer are insulated by an insulating material except for the end face. Therefore, when the ground wire is disconnected, the direct current flowing through the closed circuit is interrupted or changed, and the measuring instrument shows an almost infinite resistance value or a change in resistance value.

By utilizing this change in resistance value, it is possible to easily detect the presence or absence of a break in the ground wire.

f. Embodiment Hereinafter, a preferred embodiment of the antenna grounding wire according to the present invention will be described in detail based on the accompanying drawings.

FIG. 1 is a sectional view taken on a plane perpendicular to the axis of the ground wire, and FIG. 2 is an explanatory diagram showing how the ground wire is used. In addition, in FIG. 2, only one section of the grounding wire is shown, and the others are omitted.

As shown in FIG. 1, the grounding wire 1 has a structure in which a core wire 2, an insulating layer 3, and a conductive surface layer 4 are arranged concentrically. The core wire 2 is a wire made of a metal with high conductivity, and its outer periphery is covered with an insulating layer 3 made of an insulating material such as polyethylene. Further, the insulating layer 3 is covered with a surface layer 4 made of a highly conductive metal. It is preferable to use annealed copper for the core wire 2 and copper or aluminum for the surface layer 4. Note that the surface layer 4 can also be formed by braiding wires made of the above-mentioned materials.

The core wire 2 and the surface layer 4 are short-circuited at one end surface 5 of the ground wire 1, as shown in FIG.
This end face 5 is coated with resin to make it waterproof.

A number of similarly processed ground wires 1 are buried in the ground at a depth of 10 to 50 cm below the ground, with the antenna 6 at the center, and the core wire 2 and the surface layer 4. They are arranged radially around an end surface 7 opposite to this end surface 5, with each end surface 5 on the short-circuited side facing outward. 1 of this ground wire
The length per strip is usually λ/8 to λ/2 (λ is wavelength). Each ground wire 1 has a portion of a predetermined length from the end surface 7 exposed above the ground.

At the end surface 7 of the grounding wire 1, the surface layer 4 and the antenna 6
are connected to the output circuit 9 of the transmitter 8, respectively. Both terminals of the DC resistance measuring device 10 are connected to the core wire 2 and the surface layer 4 at the same end face 7, respectively, and the output of the measuring device 10 is connected to the alarm generator 11.
sent to. Note that, if necessary, it is preferable to provide a wave detector between the DC resistance measuring device 10 and the grounding wire 1 in order to block high frequency current from flowing through the DC resistance measuring device 10.

When the grounding wire 1 is in a normal state, the DC resistance measuring device 10 shows an extremely small resistance value, but if a break occurs in the grounding wire 1, the measuring device 10 shows an almost infinite resistance value or resistance. Indicates a change in value. on the other hand,
When the resistance value of the measuring device 10 exceeds a certain value,
The alarm generator 11 is set so that it generates an alarm. Therefore, when a disconnection occurs in the grounding wire 1, the alarm generator 11 generates an alarm to notify related parties of this fact.

In addition, the above-mentioned system is a method in which the resistance value between the core wire 2 and the surface layer 4 is always automatically measured by the DC resistance measuring device 10, and the alarm generator 11 is activated when a break in the grounding wire 1 occurs. However, it is of course possible to change the system to one in which the resistance value is measured by the measuring device 10 at any time to check whether or not the grounding wire 1 is disconnected.

The grounding wire of the present invention can have a larger outer diameter than a conventional grounding wire made of the same amount of copper, so it is possible to reduce high frequency resistance and grounding resistance.

g. Effects As described above, in the grounding wire of the present invention, the core wire made of a conductive material and the surface layer made of a conductive material are insulated by an insulating layer, and the core wire and the insulating layer are short-circuited at one end surface. Because of this structure, disconnection of the grounding wire can be easily detected by measuring the DC resistance between the core wire and the surface layer at the other end face.

[Brief explanation of drawings]

1 and 2 show an embodiment of the antenna grounding wire according to the present invention, FIG. 1 is a sectional view taken on a plane perpendicular to the axis of the grounding wire, and FIG. 2 is a use of the grounding wire. It is an explanatory view showing an aspect. 1... Ground wire, 2... Core wire, 3... Insulating layer, 4
... surface layer, 5 ... end face of ground wire, 6 ... antenna, 7 ... other end face of ground wire, 8 ... transmitter, 9
...Output circuit, 10...DC resistance measuring device, 11...
...alarm generator.

Claims (1)

[Scope of utility model registration request] It consists of a layer made of an insulating material covering a conductive core wire, and a surface layer having conductivity covering the layer made of the insulating material, and the core wire and the surface layer are short-circuited at one end face to form one circuit. 1. A grounding wire for an antenna, wherein the surface layer is connected to the antenna at the other end face.