JPH024493Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an antenna horn with a feedome used in an offset parabolic antenna (hereinafter referred to as a reflector).

[Conventional technology]

This type of antenna horn 21 with a feed dome is
As shown in FIG. 3, a circular polarization linear polarization converter 22,
It is placed at the focal point of a reflector 24 installed outdoors together with a frequency converter 23, but since its direction is generally upward, the one shown in Fig. 4 is designed to prevent rainwater, dust, etc. from entering. A membrane 26 is attached to the open end of the feed horn 25, and the membrane 26 is attached to the open end of the antenna primary horn 27 in the case shown in FIG.
8 is installed. Such a membrane is generally called a phydome. The film dome is made of a material with good dielectric constant, heat resistance, and weather resistance, and its wall thickness is set to a sufficiently small value relative to the wavelength, and Teflon fabric, plastic film, etc. are generally used.

[Problem that the invention attempts to solve]

Since the membranes 26 and 28 described above were flat and thin, they could be torn by the beaks of birds, especially birds, pigeons, etc., and reception could become impossible due to flooding.

In addition, in the offset parabolic antenna receiving device, as shown in FIG. 3, the reflector 24 is in an upright position when facing the direction in which the radio waves arrive, and especially in cold regions, the angle of elevation of the direction in which the radio waves arrive from the geostationary broadcasting satellite approaches the horizon. As a result, the antenna horn 21 at the focal point of the reflector 24 is oriented upward, so the inner part of the flanged nut 29 is exposed as shown in FIGS. 4 and 5. Circumferential stepped portion 30
The snow 31 on the membranes 26 and 28 is supported by the snow, and this snow deteriorates the antenna characteristics.

Furthermore, since current geostationary broadcasting satellites are located in the direction of the sun at around 2:00 pm on days before and after the vernal and autumnal equinoxes, the sun reflected by the reflector 24 is focused at the focal point during these times, but the conventional membrane 26 , 28 are close to this focal point, so they become quite hot, causing problems such as breakage.

[Means for Solving the Problems] In order to solve the above-mentioned problems, in the present invention, a flange portion is provided protruding from the rear end of the approximately cylindrical protrusion, and the front end is covered with a spherical portion. A field made of hard synthetic resin is attached at its flange to the open end of the horn for an offset parabolic antenna, and in this attached state, the extension line of the generatrix of the conical inner surface of the horn is near the front end of the protrusion. It is characterized by passing through the spherical part of.

[Effect]

In this invention, the antenna horn is attached to the reflector so that the spherical part made of hard synthetic resin is located in front of it, and the spherical part, which is stronger than a flat plate, is easily pecked by birds with their beaks. However, if the direction of the beak deviates from the radius of curvature of the spherical part, the beak will slip and will not be damaged. Also, when the geostationary broadcasting satellite is facing the sun, the sunlight reflected by the reflector will converge at the focal point, but the spherical part protrudes further forward from the front end of the horn through the protrusion, and the sunlight will be reflected at a position quite far from the focal point. Moreover, by having a spherical shape, the amount of heat received per unit area is significantly lower than that of a flat one, so the temperature rise in the spherical portion can be suppressed to a considerably low level. or,
Since the spherical part has a shape that is approximately perpendicular to the direction in which the radio waves arrive from the reflecting mirror, the radiation power density is more uniform than that of a flat part. Since the wave is sized to pass through a nearby spherical surface, the angle of incidence of the spherical wave on the spherical surface becomes uniformly small. However, the lower part of the fixture that attaches the feedome to the horn opening end is hidden behind the spherical part and the protruding part and cannot support the snow on the feedome from below, so even if there is snow, it will be light since there is no snow on the spherical part.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.
The one shown in FIG. 1 is attached to a flange 4 provided around the open end of the feed horn 1 of an antenna horn 3 consisting of a feed horn 1 and a primary horn 2 protruding from the inner periphery of its base. teeth,
A feedome 10 is formed by protruding a flange part 8 at the front end of a substantially cylindrical projection part 7 on a flange part 6 provided around the open end of the antenna primary horn 5, and covering the front end with a spherical part 9. flange part 8
is attached with the spherical portion 9 in front by suitable means, for example, a retaining ring 11 having a U-shaped cross section. The feed dome 10 is molded from a hard synthetic resin material, and the size of the spherical portion 9 is the same as that of the horns 1 and 5 when the feed dome 10 is attached to the open ends of the horns 1 and 5.
Extension lines 14, 15 of the generating lines of the conical inner surfaces 12, 13 of
is selected so that it passes through a spherical portion near the front end of the protrusion 7.

In this embodiment, the spherical portion 9 of the feedome 10
The outer diameter and radius of curvature are the same. Further, although the projecting portion 7 of the feed dome 10 is a cylindrical portion in this embodiment, it may be slightly tapered or rounded.

Furthermore, in the figure, 16 is a circularly polarized/linearly polarized wave converter protruding from the bases of the horns 1 and 5.

In this embodiment, a spherical part 9 made of hard synthetic resin is placed on the front side of the antenna horn and attached to the reflector 24. Even if the beak is pecked, if the peck direction deviates from the radius of curvature of the spherical portion 9, the beak will slip and will not be damaged.
Also, when the geostationary broadcasting satellite is in the direction of the sun, the sunlight reflected by the reflector will be focused at the focal point, but the spherical portion 9 will protrude further forward from the open end 17 of the horns 1 and 5 through the protruding portion 7, and the focal point will be focused. It receives sunlight from a much further away position, and because it has a spherical shape, the amount of heat received per unit area is much lower than that of a flat one, so the temperature rise in the spherical part 9 can be suppressed to a considerably low level. Furthermore, since the spherical portion 9 has a shape substantially perpendicular to the direction in which the radio waves arrive from the reflecting mirror, the radiation power density is more uniform than that of a flat one. Since the extension lines 14 and 15 of the generatrix are sized to pass through the spherical part near the front end of the protrusion 7, the spherical wave uniformly passes through the spherical part at a small incident angle. However, since the lower part of the retaining ring 11 is hidden by the spherical part 9 and the protruding part 7 which are slightly upwardly oriented, it is not possible to support the snow on the field 10 from below. It will be minor.

[Effect of idea]

As is clear from the above explanation, according to the present invention, the front surface of the hard synthetic resin feedome is spherical, so the strength is much improved compared to a flat one, and even if a bird pecks at the spherical part, the feedome will remain intact. Not easily damaged. In addition, the radiation power density of the spherical part is more uniform than that of a flat part, and since the extension of the generatrix of the conical inner surface of the horn passes through the spherical part near the front end of the protrusion, the angle of incidence of the spherical wave on the spherical part is It is uniformly small and has little electrical reflection loss. Also, by making the spherical part equal thickness,
The loss, phase, etc. of the radio waves passing through this area are uniform, resulting in good efficiency. In addition, the spherical part protrudes further forward from the front end of the horn through the protruding part, and,
Since the amount of heat received per unit area is smaller than that of a flat object, the temperature rise due to sunlight reflected by a reflecting mirror can be suppressed considerably lower than that of a flat object.
Therefore, damage to the feedome due to temperature rise can be prevented, and the material can be easily selected in terms of heat resistance, and a hard synthetic resin material with good moldability can be used. However, since there is almost no snow accumulation on the spherical surface, there is no radio wave interference due to snow accumulation, or if there is, it is only minor.

[Brief explanation of the drawing]

Fig. 1 is a side view of the present invention implemented in an antenna horn, Fig. 2 is a side view of the antenna primary horn in which the present invention is implemented, Fig. 3 is a side view of a reflector equipped with an antenna horn with a feed dome, and Fig. 4 5 and 5 are side views of the conventional product, respectively. 1...Feed horn, 2...Primary horn, 3
...Antenna horn, 5...Antenna primary horn, 7...Protrusion part, 8...Flange part, 9...
Spherical part, 10...Fidome, 12, 13...
Inner surface of cone, 14, 15... extension line of generatrix.

Claims (1)

[Scope of utility model registration request] A field made of hard synthetic resin is provided with a flange protruding from the rear end of a substantially cylindrical protrusion and the front end is covered with a spherical part, and the flange is attached to the open end of the horn for the offset parabolic antenna. An antenna horn with a feedome, characterized in that the antenna horn is mounted, and in this mounted state, an extension line of the generatrix of the conical inner surface of the horn passes through a spherical part near the front end of the protrusion.