JP3199663B2 - Waveguide with lightning surge suppression function - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waveguide having a lightning surge suppression function implemented as one of lightning protection measures in, for example, a microwave radio relay station.

[0002]

2. Description of the Related Art Conventionally, in a micro radio system, a parabolic antenna and a radio are connected by a waveguide due to the nature of radio waves used, and this waveguide is formed by a hollow copper strip pipe. The outer peripheral surface is covered with black polyethylene. Here, one end of the copper strip pipe is directly attached to the parabolic antenna, and the other end is connected to the housing of the wireless device. Is discharged from the housing of the wireless device to the ground via the parabolic antenna and the waveguide.

That is, the conventional circuit configuration is considered to be a lightning-resistant circuit system because there is no possibility that a lightning surge will enter the inside of a radio device or the like. It has not been taken yet.

[0004]

However, in practice, every time a lightning tower receives a lightning strike, damage such as damage to an electric circuit inside the radio device or occurrence of an error in transmission data frequently occurs. These are all caused by lightning surge currents that enter the housing of the wireless device from the waveguide, and it is desired to reduce the lightning surge currents by some method. The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a waveguide with a lightning surge suppression function capable of reducing a lightning surge current flowing through a waveguide.

[0005]

In order to solve the above-mentioned problems, the invention according to claim 1 connects a parabolic antenna and a radio, and guides microwaves in a waveguide for transmitting microwaves. An outer peripheral surface of the waveguide body having an elliptical cross section is covered with a metal conductor, one end of the metal conductor is connected to a parabolic antenna, and the other end of the metal conductor is connected to a ground point.

According to a second aspect of the present invention, the metal conductor is a strip metal pipe.

According to a third aspect of the present invention, the metal conductor is a metal tape.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIGS. 1A and 1B are cross-sectional views showing the structure of the first embodiment of the present invention, and FIG. 1B is viewed from the microwave waveguide direction. In the first embodiment, a waveguide main body 1 having a hollow elliptical cross section for guiding microwaves, a first anticorrosion layer 2 made of polyethylene having a hollow elliptical cross section for covering the waveguide main body 1, A shielding layer 3 made of an oxygen-free copper strip having a hollow circular cross section surrounding the first anticorrosion layer 2, and a second anticorrosion layer 4 made of polyethylene having a hollow circular cross section covering the shielding layer 3.
It is composed of

The waveguide main body 1 is, as shown in FIG.
A parabolic antenna 53 installed above a radio tower 52 of a micro radio relay station 50 built on the top of a mountain, and a micro radio 51 provided separately at the base of the radio tower 52
The transmission of microwaves is performed between the first and second transmission lines. As shown in FIGS. 1 (a) and 1 (b), the waveguide main body 1 employs a first corrosion-resistant layer 2 and a shielding layer 3 which will be described later by using an oxygen-free copper strip having a hollow elliptical cross section. , And the second anticorrosion layer 4 has a flexible structure to some extent. This is to be able to flexibly respond to the situation of the installation location. That is, by making the cross section a hollow elliptical shape,
It becomes easy to bend in the minor axis direction of the ellipse. Furthermore, by using a strip pipe (corrugated structure), unnecessary stress is prevented from being applied to the waveguide when the waveguide is bent, and microwaves can be guided without being attenuated. .

The first anticorrosion layer 2 is for electrically insulating the waveguide main body 1 from a shielding layer 3 described later.
Polyethylene is used for the material to provide flexibility.

As shown in FIG. 2, one end of the shielding layer 3 is electrically connected to the parabolic antenna 53 and the radio tower 52, and the other end is connected to a ground point provided on the base of the radio tower 52. I do. The function of the shielding layer 3 is that when the radio tower 52 or the parabolic antenna 53 is struck by lightning,
The lightning surge current flowing into the waveguide main body 3 from the light guide 3 is diverted and passed through the shielding layer 3, thereby reducing the lightning surge current flowing through the waveguide main body 1 and protecting the micro wireless device 51 from the lightning surge current. It is in. Therefore, it is preferable that the shielding layer 3 be configured to have a lower impedance than the waveguide main body 1. Specifically, the shielding layer 3 is made of a metal material having a lower electric resistance than the metal material constituting the waveguide main body 1, or the cross-sectional area of the shielding layer 3 is larger than the cross-sectional area of the waveguide main body 1. It is effective to take. The cross-sectional shape of the shielding layer 3 is different from the cross-sectional shape of the waveguide body 1 because it has a ring shape because the skin action is positively used and the high frequency component of the lightning surge current flows into the waveguide body 1. This is to prevent In the present embodiment, the barrier layer 3 is made of an oxygen-free copper strip having a hollow true circular cross section, which is flexible and easy to manufacture.

The function of the second anticorrosion layer 4 is to protect the waveguide main body 1 and the shielding layer 3 from wind and rain. Like the first anticorrosion layer 2, polyethylene is used for the material to provide flexibility.

FIGS. 3A and 3B are cross-sectional views showing the structure of a second embodiment of the present invention, and FIG. 3B is viewed from the microwave guiding direction. Only differences from the first embodiment will be described. In the second embodiment, a shielding layer 5 in which a copper tape is wound around the outer periphery of the first anticorrosion layer 2 is used instead of the shielding layer 3 of the first embodiment. The method of use and operation are the same as in the first embodiment. In this embodiment, compared to the first embodiment, the cross-sectional area of the entire waveguide can be reduced, and the size can be further reduced.

Next, a description will be given of the result of an experiment on how a lightning surge current is shunted using a circuit incorporating the first embodiment. Table 1 is a table showing the experimental results.

[0015]

[Table 1]

The specific circuit configurations of the test circuits A, B and C shown in Table 1 are shown in FIGS. 4, 5 and 6, respectively.
Shown in In this experiment, a current of 450 A was applied to the upper part of the wireless tower, and the current flowing to a predetermined position in each circuit was measured.
Actually, there are two sets of test circuits A, B, and C, and the numerical values in Table 1 show the total value (unit A) of the currents at the predetermined positions of the two sets. In addition,
The numerical values in parentheses indicate the ratio of the sum to the applied current of 450 A in percentage. In addition, FIG.
The same applies to the numerical values shown in the circuits 5 and 6.

FIG. 4 is a circuit diagram showing a test circuit A according to the related art. Although the first embodiment (indicated as SR in the figure) is incorporated in a part of an outdoor waveguide (outdoor WG), the shielding layer 3 is not electrically connected. The same is true. The outdoor WG shown in Table 1 indicates a current flowing through the outdoor waveguide. Furthermore, the rectangular WG indicates a current flowing through the indoor rectangular waveguide to the micro wireless device 51. In FIG. 4, the flange FR is member connecting the waveguides to each other variants, de Haidoreta D is a blower for sending dry air into the waveguide.

A test circuit B shown in FIG. 5 is a circuit obtained by incorporating the first embodiment into the test circuit A and making it function. That is, one end of the shielding layer 3 of the first embodiment SR is electrically connected to the parabolic antenna 53, and the other end of the shielding layer 3 is connected to the ground point (indicated by PE in the figure) of the base of the wireless tower and the micro wireless communication. It is electrically connected to a ground point (indicated by E in the figure) of the machine 51. In Table 1, SR indicates a current flowing through the shielding layer 3 to the ground point PE. The test circuit B can confirm the direct effect of the first embodiment.

The test circuit C shown in FIG. 6 is obtained by electrically connecting the parabolic antenna 53 and the ground point PE at the base of the wireless tower 52 to the test circuit B by a vinyl insulated wire (IV wire). The IV shown in Table 1 corresponds to the I
The current flowing through the V line to the ground point PE is shown. The IV line serves to shunt the applied current together with the shielding layer 3 of the first embodiment and reduce the current flowing through the waveguide body 1.

As is clear from the results shown in Table 1, by using the first embodiment as an outdoor waveguide, the current flowing through the outdoor waveguide main body is reduced from 16.9 A to 9.9 A.
And finally the current flowing into the micro wireless device 51 through the indoor rectangular waveguide can be drastically reduced from 8.9 A to 5.3 A. Furthermore, by adding an IV line, the current flowing in the outdoor waveguide body can be reduced, and the current flowing into the micro wireless device 51 through the indoor rectangular waveguide can be reduced. When the numerical value of the test circuit C in Table 1 is compared with the numerical value of the test circuit B, it seems at first glance that the current value has increased.
This is due to the difference between the conditions of the test circuit C and the test circuit C (the currents flowing through the tower (not shown) are different). This can easily be inferred from the fact that a current of 21.8 A flows through the newly provided IV line.

[0021]

As described above, according to the first, second, and third aspects of the present invention, a lightning surge current passing through the waveguide body can be reduced, so that the electric circuit inside the micro wireless device is caused by the lightning strike. Inconveniences such as damage or errors in transmission data can be eliminated.

Further, according to the first, second and third aspects of the present invention,
By installing an insulated wire that electrically connects the parabolic antenna and the ground, and mounting a magnetic material around the waveguide (not shown in the figure), a lightning protection system that is more secure against lightning strikes is constructed. can do.

[Brief description of the drawings]

FIG. 1 is a sectional view of a first embodiment.

FIG. 2 is a diagram illustrating a use state of the embodiment.

FIG. 3 is a sectional view of a second embodiment.

FIG. 4 is a circuit diagram of a test circuit A.

FIG. 5 is a circuit diagram of a test circuit B.

FIG. 6 is a circuit diagram of a test circuit C.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Waveguide main body 2 1st anticorrosion layer 3 Shielding layer 4 2nd anticorrosion layer 5 Shielding layer

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI H05K 9/00 H05K 9/00 A (72) Inventor Yoshikatsu Hirano 1-2-23 Oshima, Koto-ku, Tokyo Shodenai Co., Ltd. (72 ) Inventor Miyuki Kumada 1-2-23 Oshima, Koto-ku, Tokyo Shodennai Co., Ltd. (72) Inventor Ryo Takei 1-2-23 Oshima, Koto-ku, Tokyo Shodennai Co., Ltd. (56) References JP1 -278101 (JP, A) JP-A-58-225507 (JP, A) JP-A-61-214804 (JP, A) JP-A-9-271138 (JP, A) (58) Fields investigated (Int. . ^7, DB name) H01P 3/14 H01P 3/12 H01Q 1/50 H01Q 19/12 H02H 9/02 H05K 9/00 JICST file (JOIS)

Claims (3)

(57) [Claims] 1. A parabolic antenna and a radio are connected,
In a waveguide for transmitting microwaves, an outer peripheral surface of a waveguide main body having an elliptical cross section for guiding microwaves is covered with a metal conductor, and one end of the metal conductor is connected to a parabolic antenna, and A lightning surge suppression function, wherein the other end of the light guide is connected to a ground point. 2. The waveguide with a lightning surge suppression function according to claim 1, wherein the metal conductor is a strip metal pipe. 3. The waveguide with a lightning surge suppression function according to claim 1, wherein the metal conductor is a strip of metal tape.