JPH071850Y2 - Snow melting cover for antenna - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a snow melting cover for an antenna, and more particularly to a snow melting cover for a broadcasting antenna for a train or the like.

[Conventional technology]

Conventionally, in a snow melting cover used in a snowy area or the like, electrically conductive (heat generating) fibers are woven in the longitudinal and lateral directions of a heating element.

[Problems to be solved by the invention]

Therefore, the radio wave for broadcasting is shielded by 30 dB or more,
For example, it was difficult to use it as a snow melting cover for a broadcasting antenna of a train or the like.

[Purpose of device]

The present invention has been devised in view of such conventional problems, and an object thereof is to provide a snow melting cover for an antenna that can be effectively used as a snow melting cover for a broadcasting antenna of a train or the like. is there.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, the present invention has a gist that a cover body made of a non-conductive material such as glass fiber or acrylic is combined with a planar heating element woven with heating fibers only in one direction. It is a thing.

[Function of device]

This device is constructed as described above, and since the heat-generating fibers are woven in only one direction, radio waves having a plane of polarization parallel to the heat-generating fibers enter, and therefore have the permeability of broadcast radio waves. Moreover, since it has a heat capacity for melting snow, it can be used for trains as a snow melting cover for antennas.

[Example of device]

An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a partial perspective view of a train car 1 embodying the present invention, 2 is a parabolic antenna for broadcasting incorporated in the train car 1, and 3 is a snow melting cover for covering the parabolic antenna 2.

The snow melting cover 3 is formed by laminating a cover body 4 made of a non-conductive material such as glass fiber or acrylic and a heating element 5.

Next, the structure of the heating element 5 will be described in further detail with reference to FIG. 3. Insulating portions 7 are formed at both end portions of the heat-generating fiber 6 in the longitudinal direction, and the end portion A power supply unit 8 is provided in the. The exothermic fiber 6 is woven at a ratio of 1 to 5 nylon fibers, and is woven so that the exothermic fibers 6 do not contact each other.

In this invention, since the configuration is as described above, radio waves having a polarization plane parallel to the heat-generating fiber 6 penetrates, and therefore, the radio waves for broadcasting are transparent and have the heat of lamination melting. It can be used for trains etc. as a snow melting cover for antennas.

Since the broadcast radio wave may be considered in the far field, there is a radio wave having a plane of polarization parallel to the heat generating fiber 6.

Next, the shield theory regarding the hole (d <t) in the thin barrier will be described.

The shield is as follows when the longest dimension of the gap is d and the wavelength of the radiation field is λ.

． Whether the wavelength λ is less than twice the dimension of the longest gap,
Or if equal.

λ ≤ 2d: Shield is zero. When the wavelength λ is larger than 2d.

λ> 2d, the shield can be expressed by RdB = 20logλ / 2d.

In the case of the embodiment of the present invention, since it is used at 1 GHz to 15 GHz, the wavelength λ is λ = 2 to 30 cm.

Therefore, 2d ≧ λ = 2 to 30 cm, d = 1 to 15 cm, and if the length of the heat-generating fiber 6 is 15 cm, the shield can be zero.

Therefore, it is necessary to determine the length of the heat-generating fiber 6 according to the wavelength λ of the radio wave used.

From the above, it is clear that when the heat-generating fibers 6 are incorporated in the longitudinal direction and the lateral direction of the heating element as in the conventional case, d is extremely small and the shield is large.

[Effect of device]

In this invention, as described above, the cover body made of a non-conductive material such as glass fiber or acrylic is combined with the planar heating element in which the heating fiber is woven only in one direction.
It has an effect that it can be effectively used as a snow melting cover for a broadcasting antenna of a train or the like.

[Brief description of drawings]

FIG. 1 is a partial perspective view of a train car in which the present invention is implemented,
FIG. 2 is a sectional view taken along the line II-II of FIG. 1, and FIG. 3 is a detailed explanatory view of a heating element. 3 ... snow melting cover, 4 ... cover body, 5 ... heating element,
6 ... Exothermic fiber.

Claims (1)

[Scope of utility model registration request] 1. A snow melting cover for an antenna, comprising a cover body made of a non-conductive material and a planar heating element in which heating fibers are woven only in one direction.