JP3350373B2 - Double reflector type small-diameter parabolic antenna device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double-reflector type parabolic antenna device having a main and a sub-reflector, and more particularly to a small-diameter double-reflector used in ordinary households for receiving satellite broadcasting and satellite communication. The present invention relates to a parabolic antenna device.

[0002]

2. Description of the Related Art FIG. 16 shows an example of a conventional parabolic antenna device of the double reflection mirror type. In this figure, 1 is a main reflecting mirror, 2 is a sub-reflecting mirror, 3 is a stay supporting the sub-reflecting mirror, 4
Is a waveguide feeder, and 5 is a radome that covers the front opening of the main reflecting mirror. In this case, since the waveguide feeder 4 is separated from the sub-reflecting mirror 2 and the sub-reflecting mirror itself is large, the sub-reflecting mirror 2 must be fixed using the stay 3.
In addition, the radome 5 also increases in size accordingly.

In the conventional apparatus shown in FIG. 16, an electromagnetic wave incident on a main reflecting mirror 1 is reflected by a main reflecting mirror 1 toward a sub-reflecting mirror 2 located at a focal position thereof, and further reflected by a sub-reflecting mirror 2 and guided. It is guided into the tube feeder 4.

A conventional double-reflecting mirror type parabolic antenna apparatus has a small-diameter satellite broadcast and satellite communication used in ordinary homes at two points, (1) the diameter of the antenna apparatus and (2) the depth of the antenna apparatus. It was not suitable for a receiving antenna device.

First, regarding (1), in the conventional double-reflecting mirror type parabolic antenna device, the diameter of the sub-reflecting mirror is generally about 1/10 of the diameter of the main reflecting mirror. In order to work as a reflecting mirror, the wavelength of
It was said that a double diameter was required ("Antenna Engineering Handbook", pp. 160, 161, edited by the Institute of Electronics and Communication Engineers, Ohmsha, October 30, 1980, first edition, first printing). Therefore, the diameter of the main reflector of this antenna device needs to be about 100 times the wavelength of the operating frequency. Specifically, in the 12 GHz band which is the operating frequency of satellite broadcasting and satellite communication, one wavelength is 25 mm. To provide a double-reflector parabolic antenna device with a main reflector with a diameter of 2.5 m or more and a sub-reflector with a diameter of about 25 cm, providing a small-diameter satellite broadcasting and satellite communication receiving antenna device for ordinary households. Contrary to the object of the present invention to be sought.

[0006] Regarding (2), as shown in FIG. 16, in the conventional double-reflecting mirror type parabolic antenna device, the tip of the primary radiator including the sub-reflecting mirror 2 has the opening of the main reflecting mirror 1. It is easily affected by wind, rain and snow because it protrudes from

[0007]

As described above, the configuration of the conventional double-reflector mirror type parabolic antenna apparatus results in a parabolic antenna apparatus having a main reflector having a diameter of 2.5 m. It is difficult to use it as an antenna device for satellite broadcasting and satellite communication reception.
In addition, it is effective means to attach a radome to the opening of the main reflector of the parabolic antenna device in order to prevent the effects of wind, rain and snow, but with the above-mentioned conventional configuration, the diameter of the main reflector is large. Further, since the depth is large, the radome itself is also large, and is not suitable in terms of size and cost as an antenna device for satellite broadcasting and satellite communication for general home use.

[0008] A first object of the present invention is to solve the above problems,
Provided is a double-reflector-type small-diameter parabolic antenna apparatus which can reduce the diameters of a main reflector and a sub-reflector, secure required efficiency, and can be suitably used for satellite broadcasting and satellite communication reception in ordinary households. The purpose is to:

A second object of the present invention is to reduce the depth of the primary radiator by suppressing the projection of the distal end of the primary radiator from the opening of the main reflector having a small diameter, and to mount a radome having a nearly flat shape. It is an object of the present invention to provide a double-reflection mirror type small-diameter parabolic antenna device which can easily take measures against wind, rain and snow and is suitable for reduction in size and thickness.

[0010] Other objects and novel features of the present invention will be clarified in embodiments described later.

[0011]

In order to achieve the above object, a small-diameter double-reflector-type parabolic antenna apparatus according to the present invention comprises a small main reflector having a parabolic surface and a near-focus point of the main reflector. , A small sub-reflector having a hyperboloid located at a point, a feeding means using a circular waveguide whose tip is located near the focal point of the sub-reflector, and a converter connected to the circular waveguide. A reflector type parabolic antenna device, wherein the diameter of the main reflector is D, the diameter of the sub-reflector is d, the focal length of the main reflector is F, and the distance from the center of the main reflector to the sub-reflector is When the distance to the focal point is F ′, the distance between the focal position of the main reflecting mirror and the focal position of the sub-reflecting mirror is FF ′, and the wavelength of the electromagnetic wave is λ, 0.25 ≦ F / D ≦ 0 .30 18λ ≦ D ≦ 22λ 2λ ≦ d ≦ 3λ 1.0λ ≦ FF ′ ≦ 1.5λ It is.

In the above-mentioned double-reflector type small-diameter parabolic antenna apparatus, the sub-reflector and the tip of the circular waveguide are connected to each other via a low-permittivity synthetic resin hollow structure. The sub-reflector is set at a predetermined position by a structure, and the sub-reflector and the hollow structure and the circular waveguide and the hollow structure are joined together in a water-tight manner using elastic waterproof means. It can be configured.

[0013] The circular waveguide may have a straight pipe with an inner shape of the same diameter from the root to the tip, or a straight pipe with an inner shape of the same diameter from the root to the vicinity of the tip and the tip. The tapered horn only, or the inner shape is a tapered shape that gradually expands from the root to the tip from the tip, the circular waveguide and the The connection with the converter may be screwed by screws and may be detachable.

Further, the transmission mode of the circular waveguide is T
A E _11, the input of the converter can be configured with a horizontal and vertical two orthogonal probes in circular waveguide structure.

An opening of the main reflecting mirror is covered with a radome having a water repellency and a nearly flat shape together with the sub-reflecting mirror, and an elastic molding is formed over the entire periphery of a flange formed at an opening edge of the main reflecting mirror. A plurality of locking convex portions are formed inside the fitting portion of the radome that is fitted and fitted to the flange portion of the main reflector, and the fitting portion is detachably attached to the outside of the elastic molding. The fitting convex portion may be pressed and engaged with the elastic molding while being fitted.

[0016]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a double-reflector type small-diameter parabolic antenna according to an embodiment of the present invention.

FIG. 1 is a side sectional view showing the overall configuration of the first embodiment according to the present invention, FIG. 2 is a schematic configuration diagram showing the dimensional relationship of FIG. 1, and FIG. 3 is an enlarged view of the primary radiator. FIG.

As shown in these figures, the double-reflection mirror type small-diameter parabolic antenna apparatus comprises a small-sized, small-diameter main reflector (parabolic reflector) 11 and a portion near the focal point f of the main reflector 11 (focal point f). And a small-diameter, small-aperture sub-reflector 12 disposed on the front side of the sub-reflector 12, and a circular waveguide feeder 13 serving as a power supply unit disposed so as to open near the focal point f ′ of the sub-reflector 12. And

The main reflecting mirror 11 is a concave mirror formed by molding a metal plate or metallizing the surface of a synthetic resin or the like. In order to form a so-called parabolic antenna device, a parabolic reflecting mirror having a parabolic reflecting surface is used. It is. The sub-reflection mirror 12 is a convex mirror formed by molding or processing metal or metallizing the surface of a synthetic resin or the like to have a reflection surface 12a. In order to obtain a Cassegrain antenna device, a hyperboloid reflection having a hyperboloid reflection surface is used. It is a mirror.

The circular waveguide feeder 13 has an open end, and the end constitutes a primary horn for transmitting or receiving electromagnetic waves. However, in the present embodiment, the inner shape of the circular waveguide feeder 13 is exemplified by a straight pipe having the same diameter from the root to the tip.
The circular waveguide feeder 13 has a center feed structure extending through the center of the main reflecting mirror 11 to the focal point f ′ of the sub-reflecting mirror 12.
It is preferable that the focal point f 'is located slightly inside the opening 13a. The root of the circular waveguide feeder 13 is connected to a converter (frequency converter) 14.
Together with the converter 14, it is fixed and supported on a base member 15 fixed on the back side of the main reflecting mirror 11.

As shown in FIG. 3, the sub-reflection mirror 12 and the tip of the circular waveguide feeder 13 are made of a material that transmits an electromagnetic wave, that is, a fidome 16 of a synthetic resin hollow structure having a low dielectric constant. The sub-reflector 12 is fixed at a predetermined position by the fidome 16, and the tip of the circular waveguide feeder 13 and between the sub-reflector 12 and the fidome 16 to maintain watertightness. And the above-mentioned fidome 16 are fitted by using a waterproof means (for example, a waterproof component such as an O-ring) 17 of an elastic material such as rubber,
It is integrated. The sub-reflector 12 and the fidome 16
Alternatively, the configuration may be such that the circular waveguide feeder 13 and the fidome 16 are joined together while maintaining a watertight state with an adhesive.

The connecting portion between the base of the circular waveguide feeder 13 and the converter 14 includes a male screw 13b at the base of the circular waveguide feeder 13, and a female screw 14b at the input joint 14a of the converter 14. Are formed respectively. The circular waveguide feeder 13 passes through the center hole 11a of the main reflecting mirror 11 and reaches the back side, and the converter 14 is connected to the base extending to the back side of the main reflecting mirror. That is, the male screw 13b at the base of the circular waveguide feeder 13 is screwed to the female screw 14b on the converter side. As a result, the primary radiator portion having the sub-reflector 12 and the circular waveguide feeder 13 is detachable from the main body having the main reflector 11. In addition, the circular waveguide feeder 1
3 and the input joint 14 of the converter 14
In order to maintain a watertight space between a and a, a waterproof part (for example, an O-ring or the like) made of an elastic material such as rubber is provided at a portion of the base of the circular waveguide feeder 13 which fits into the converter-side joint portion 14a.
8 are provided.

FIGS. 4 to 6 show examples of the structure of the receiving probe section 20 of the converter 14. FIG. Two orthogonal and horizontal orthogonal probes 2 constituting the receiving probe unit 20
By providing 0a and 20b in the circular waveguide section 21 (continuous with the same inner diameter as the circular waveguide feeder 13) on the input side of the converter 14, the converter 14 can control both the horizontal polarization and the vertical polarization. It is possible to receive. Furthermore, it is also possible to receive right-handed and left-handed circularly polarized waves by combining horizontal and vertical polarizations. In addition, two orthogonal probes 2
0a and 20b are directed to the center direction of the circular waveguide section 21 in the vertical cross section of the circular waveguide section 21 and are in the same plane as shown in FIG. It is fixed at a position separated in the direction.

The received electromagnetic wave reflected by the main reflecting mirror 11 and the sub-reflecting mirror 12 and entering the opening of the circular waveguide feeder 13 is transmitted inside the circular waveguide feeder 13 in the TE ₁₁ mode. The signal is received by the reception probe unit 20. As described with reference to FIGS. 4 to 6, the receiving probe unit 20 of the converter 14 includes two orthogonal probes 20a and 20b orthogonal to each other, and therefore receives both the horizontal polarization and the vertical polarization. Is possible. further,
It is also possible to receive right-handed and left-handed circularly polarized waves by combining horizontal and vertical polarizations.

The radome 3 is provided at the opening of the main reflecting mirror 11.
0 is attached. The radome 30 covers the sub-reflecting mirror 12 together with the opening of the main reflecting mirror 11 and has a nearly flat shape (in the present embodiment, a nearly flat shape in which the central portion is slightly higher than the peripheral portion). It is formed of a material that transmits electromagnetic waves, that is, a plastic plate having a low dielectric constant. In addition, the surface is coated with a water-repellent material such as a fluororesin in order to prevent adhesion of rainwater, snow and the like. The radome need not be mounted in an environment free from rainwater, snow, and the like.

As shown in FIG. 7, in order to enhance the adhesion of the radome 30 to the main reflecting mirror 11 side and to prevent rainwater from entering the inside of the radome 30, a flange serving as an outer edge of the main reflecting mirror 11 is provided. An elastic molding 31 made of rubber or the like is mounted on the entire periphery of the portion 11b. The outer edge of the radome 30 is formed as a circumferential fitting portion 30a. In order to lock the radome 30 on the front surface of the main reflecting mirror 11 so as not to fall off, FIG.
As shown in FIG. 8, a plurality of locking projections 30b projecting inward from a plurality of locations are formed integrally with the circumferential fitting portion 30a. Each locking projection 30b can be slightly bent by forming the radome 30 with a plastic plate or the like. Then, the elastic molding 3 on the main reflecting mirror 11 side
1 is fitted with the circumferential fitting portion 30a of the radome 30, and the locking convex portion 30b is pressed against and engaged with the elastic molding 31 slightly behind the flange portion 11b to form the locking convex portion. Part 3
0b bites into the elastic molding 31. As described above, the radome 30 is fitted and closely attached to the main reflecting mirror 11 with the elastic molding 31 interposed therebetween, so that the radome 30 can be securely mounted. According to this configuration, the radome 30 can be attached and detached without using a tool.

Here, conditions for realizing a small and small-diameter double-reflector mirror type parabolic antenna device for general household use, which is different from the conventional double-reflector mirror type parabolic antenna device, will be described. That is, the conditions for making the main reflector 11 and the sub-reflector 12 small in diameter and for reducing the amount of projection of the primary radiator having the sub-reflector 12 from the opening of the main reflector are set in FIG. The study will be made with reference to a schematic configuration diagram showing a dimensional relationship of the focal point, focal length, and the like of the mirror 11 and the sub-reflector 12. In FIG. 2, the diameter of the main reflector 11 is D, the diameter of the sub reflector 12 is d, the focal position of the main reflector 11 is f, the focal length of the main reflector 11 is F, and the focal position of the sub reflector 12 is f ', the main reflecting mirror 11
F ′, the distance from the center of
The distance between the focal position of the main reflecting mirror 11 and the focal position of the sub-reflecting mirror 12 is FF ′, the wavelength of the electromagnetic wave is λ, the opening surface of the main reflecting mirror 11 (a plane passing through the opening edge of the main reflecting mirror 11). S) is the amount of projection of the focal point position f from the point).

As can be seen from FIG. 2, since the sub-reflector 12 needs to be disposed near the focal point f of the main reflector 11 (slightly forward of the focal point f), the primary radiation having the sub-reflector 12 is required. In order to reduce the projection amount of the reflector, it is necessary to set the focal length F smaller than the diameter D of the main reflecting mirror 11.

FIG. 9 shows the focal length F and the diameter D of the main reflecting mirror 11.
Is plotted on the horizontal axis, and the ratio S / of the projection amount S of the focal position f from the opening surface of the main reflecting mirror 11 to the diameter D of the main reflecting mirror 11
The relationship between F / D and S / D is obtained with D (%) as the vertical axis. From this figure, it is possible to suppress the projection amount S of the focal position f of the main reflecting mirror 11 to 10% or less of the diameter D of the main reflecting mirror 11 by setting the F / D to 0.3 or less. When D = 0.25, the focal position f of the main reflecting mirror 11
Is zero, and it can be seen that a flat radome can be mounted on the main reflecting mirror 11. In view of this point, in the present embodiment, 0.25 ≦ F / D ≦ 0.30 is set.

If 0.3 <F / D, the projection amount S becomes excessively large, the depth of the antenna device becomes large, and the shape of the radome 30 also becomes a shape with the center protruding. It is inappropriate because it is more susceptible. Even if F / D <0.25, F / D = 0.25
The effect of reducing the depth dimension is not as compared with the case of (1), and the efficiency is rather lowered.

As described above, in order to reduce the F / D ratio of the main reflecting mirror 11 (by setting 0.25 ≦ F / D ≦ 0.30) and reduce the projection of the primary radiator, the main reflection It is necessary to increase the aperture angle of the mirror 11, and in this case, it is necessary to widen the directivity of the sub-reflector 12 in accordance with the main reflector 11.
Accordingly, the directivity of the circular waveguide feeder 13 also needs to be widened in accordance with the sub-reflector 12. To satisfy this condition, a straight pipe having the same diameter may be used as it is without tapering the opening of the circular waveguide feeder 13. That is, when the dimension FF ′ is in the range of 1.0λ to 1.5λ, the directivity in the case of a straight pipe shape having the same diameter is suitable.

Here, the conditions of the small, small-diameter, double-reflector-type parabolic antenna apparatus suitable for general household use are as follows.
1 is D, the diameter of the sub-reflector 12 is d,
Is F, the distance from the center of the main reflector 11 to the focal point of the sub-reflector 12 is F ′, and the distance between the focal position of the main reflector 11 and the focal position of the sub-reflector 12 is F −
F ′, when the wavelength of the electromagnetic wave is λ, F / D = 0.30 18λ ≦ D ≦ 22λ 2λ ≦ d ≦ 3λ 1.0λ ≦ F−F ′ ≦ 1.5λ 10 and FIG. 11 were obtained.

FIG. 10 shows the diameter D of the main reflecting mirror 11 = 18λ.
The focal position f of the main reflector 11 and the sub-reflector 12
The relationship between the distance FF 'between the focal positions f' and the antenna aperture efficiency is shown using the diameter d of the sub-reflector 12 as a parameter. According to this result, by changing the curved surface of the sub-reflecting mirror 12, the distance FF ′ between the focal position f of the main reflecting mirror 11 and the focal position f ′ of the sub-reflecting mirror 12 can be changed. In combination with the tube feeder 13, the minimum F
−F ′ dimension can be brought close to 1.0λ, and F ′
If the −F ′ dimension is in the range of 1.0λ to 1.5λ, the antenna aperture efficiency of 60% or more can be obtained when the diameter d of the sub-reflector 12 is in the range of 2λ to 3λ. Note that the definition of the antenna aperture efficiency is such that when an aperture antenna such as a reflector antenna is considered, the efficiency at which the maximum gain is obtained by calculation with the diameter of the antenna is 100%, and the actual gain is It is expressed as a percentage based on the maximum gain.

FIG. 11 shows the diameter D of the main reflecting mirror 11 = 22λ.
The relationship between the distance FF ′ and the aperture efficiency of the antenna is expressed by using the diameter d of the sub-reflector 12 as a parameter. Also in this case, if the FF ′ dimension is in the range of 1.0λ to 1.5λ, the characteristic that the antenna aperture efficiency is 60% or more can be obtained when the diameter d of the sub-reflector 12 is in the range of 2λ to 3λ. You can see that it is done.

FIGS. 10 and 11 both show F / D =
The measured value is 0.30, but almost the same result is obtained when the F / D is changed to 0.25.

From the above results, each condition should be set as follows: 0.25 ≦ F / D ≦ 0.30 18λ ≦ D ≦ 22λ 2λ ≦ d ≦ 3λ 1.0λ ≦ FF ′ ≦ 1.5λ According to the present invention, it is possible to provide a small-sized, small-diameter, double-reflector-type small-diameter parabolic antenna device suitable for use in general homes, which is capable of mounting a nearly flat radome and is not easily affected by wind, rain, and snow. The object of the present invention can be achieved. As an example of the actual dimensional relationship, when the frequency is 12.5 GHz, (λ = 24 mm)
The diameter D of the main reflecting mirror 11 and the diameters d and F of the sub-reflecting mirror 12
The possible value of -F 'is 432 mm ≤ D ≤ 528 mm 48 mm ≤ d ≤ 72 mm 24 mm ≤ FF' ≤ 36 mm when F / D = 0.30, and even if the largest value is selected, its size is The size is reduced to about 1/5 of that of the conventional antenna, and the size can be reduced.

If the diameter D of the main reflecting mirror 11 is made larger than 22λ, inconveniences such as an increase in the diameter of the main reflecting mirror 11, an increase in the depth dimension, an increase in the weight, an increase in the installation space, and the like occur. It is inappropriate because it is no longer suitable for home use.
If the diameter D is smaller than 18λ, the receiving sensitivity is lowered, and it is difficult to maintain the aperture efficiency at 60% or more.

If the diameter d of the sub-reflection mirror 12 is larger than 3λ, the shape and weight become too large, and the aperture efficiency is rather lowered due to the effect of blocking or the like. This is unsuitable because it causes a decrease in the aperture efficiency (in any case, it is difficult to maintain the aperture efficiency at 60% or more).

Further, the distance FF 'between the focal position f of the main reflecting mirror 11 and the focal position f' of the sub-reflecting mirror 12 is larger than 1.5λ, as is apparent from FIGS. Any case where the aperture efficiency is smaller than 1.0 is inappropriate because the aperture efficiency is reduced (in any case, it is difficult to maintain the aperture efficiency at 60% or more).

According to the first embodiment of the present invention,
The following effects can be obtained.

(1) In the first embodiment of the present invention, the primary radiator having the sub-reflector 12 has a wide directivity in order to efficiently match the main reflector 11 having a deep dish-like shape and a wide opening angle. In addition, the directivity of the opening of the circular waveguide feeder 13 has a wide directivity similarly to the sub-reflector 12. Thereby, the range of the value of F / D is set to 0.25 ≦
The efficiency at the time of setting F / D ≦ 0.30 is kept good, and the amount of protrusion of the tip of the primary radiator from the opening surface of the main reflecting mirror is reduced to 1/10 or less of the diameter D of the main reflecting mirror 11. can do. For this reason, the projection of the primary radiator can be suppressed and the depth can be reduced. Although the antenna size, that is, the diameter of the main reflecting mirror 11 is about 1/5 smaller than that of the conventional double reflecting mirror type parabolic antenna device, the antenna aperture efficiency can secure 60% or more. Not inferior to Further, by shortening the distance between the sub-reflector 12 and the tip of the circular waveguide feeder 13 (1.0λ ≦ FF ′)
≦ 1.5λ), the means for fixing the sub-reflector 12 can be simplified.

(2) As described above, the amount of protrusion of the tip of the primary radiator from the opening surface of the main reflector is reduced to one-tenth or less of the diameter D of the main reflector 11, thereby suppressing the protrusion of the primary radiator. Since the depth can be reduced, the opening surface of the main reflecting mirror 11 can be easily covered with the radome 30, and the radome 30 can be formed into a gentle curved surface shape close to a planar shape.
Further, by making the surface of the radome a highly water-repellent material (fluorine resin or the like), it is possible to easily drop the attached rainwater and snow. As a result, it is possible to obtain a double-reflector type small-diameter parabolic antenna device which is compact (small diameter and small depth) and has a small mounting space, and is not easily affected by wind, rain and snow.

[0043] (3) employs a circular waveguide feeder 13 as the feeding means, since the transmission mode is a TE _11, is connected to its rear, horizontal and vertical two orthogonal probes 20a, 20b are It is possible to receive both horizontal polarization and vertical polarization by combining with a converter 14 having a polarization switching function. Furthermore, it is also possible to receive right-handed and left-handed circularly polarized waves by combining horizontal and vertical polarizations.

(4) The distance between the circular waveguide feeder 13 and the sub-reflection mirror 12 is set short, and the sub-reflection mirror 12 and the tip of the circular waveguide feeder are made of a low dielectric constant synthetic resin hollow structure. They are connected to each other via a body fidome 16, by means of which the secondary reflector 12 can be fixed in place.
For this reason, a special member (stay or the like) for supporting the sub-reflector 12 is not required, and the structure can be simplified and the size can be reduced. The sub-reflector 12 and the fidome 1
6 and between the circular waveguide feeder 13 and the fidome 16 are joined in a watertight manner by using an elastic waterproof part 17,
The waterproofness is further improved.

(5) The circular waveguide feeder 13 is easy to manufacture and can be manufactured at a low cost, and the connection between the circular waveguide feeder 13 and the converter 14 is screwed with screws and is detachable. Easy to disassemble and assemble.

(6) An elastic molding 31 is mounted over the entire periphery of the flange portion 11b formed on the opening edge of the main reflecting mirror 11, and the circumferential fitting portion 30 of the radome 30 fitted here is fitted.
By forming a plurality of locking projections 30b inside of a, the circumferential fitting part 30a is fitted to the outside of the elastic molding 31 and the radome 30 is attached to the main reflector opening. In addition, the locking convex portion 30b is pressed against and engaged with the elastic molding 31, so that the radome 30 can be held so as not to fall off. The radome 30 is detachable from the main reflecting mirror 11 and can be attached to and detached from the main reflecting mirror 11 without using a tool.

In the first embodiment, a straight pipe having an inner shape of the same diameter from the root to the tip is used as the circular waveguide feeder. In this case, impedance matching of the opening cannot be obtained. , VSWR (voltage standing wave ratio) may be deteriorated. A configuration in consideration of this point will be described in the following second embodiment.

FIG. 12 is a side sectional view showing the overall configuration of the second embodiment according to the present invention, FIG. 13 is a schematic configuration diagram showing the dimensional relationship of FIG. 12, and FIG. 14 is an enlarged view of the primary radiator. FIG.

As shown in these figures, the double-reflection mirror type small-diameter parabolic antenna apparatus has a small-sized and small-diameter main reflector (parabolic reflector) 11 and a portion near the focal point f of the main reflector 11 (focal point f). And a small-diameter, small-aperture sub-reflector 12 disposed on the near side of the sub-reflector 12, and a circular waveguide feeder 23 serving as a power supply unit disposed so as to open near the focal point f ′ of the sub-reflector 12. And The circular waveguide feeder 23 is a straight pipe 24 having an inner shape of the same diameter from the root portion to the vicinity of the tip portion, and only a tip portion (opening portion) becomes a horn-shaped portion 25 which is tapered and opened. ing. The tip of the horn-shaped portion 25 is open, and is configured to transmit or receive an electromagnetic wave. However, the horn-shaped portion 25 is set to a small shape that does not significantly affect the directivity.

The circular waveguide feeder 23 penetrates through the center of the main reflecting mirror 11 and the focal point f ′ of the sub-reflecting mirror 12.
, And the focal point f ′ is preferably located slightly inside the opening 23 a of the circular waveguide feeder 23.

At the connection between the root of the circular waveguide feeder 23 and the converter 14 on the rear side of the main reflecting mirror 11, a male screw 23b is provided at the root of the circular waveguide feeder 23.
The female screw 1 is connected to the input side joint portion 14a of the converter 14.
4b are formed respectively. The circular waveguide feeder 23 reaches the back side through the center hole 11a of the main reflecting mirror 11, and the converter 14 is connected to the base extending to the back side of the main reflecting mirror. That is, the male screw 23b at the base of the circular waveguide feeder 23 is screwed to the female screw 14b on the converter side. As a result, the primary radiator portion having the sub-reflector 12 and the circular waveguide feeder 23 is detachable from the main body having the main reflector 11.

The other configuration is the same as that of the first embodiment described above, and the same or corresponding portions are denoted by the same reference characters and description thereof is omitted.

According to the second embodiment, in addition to the function and effect of the first embodiment, the tip of the circular waveguide feeder 23 has a small horn shape with a taper. Therefore, the impedance matching at the opening of the circular waveguide feeder can be improved, and the deterioration of the VSWR can be suppressed to improve the characteristics.

FIG. 15 shows a third embodiment of the present invention, which also shows a configuration in which VSWR is taken into consideration. In this figure, a double-reflection mirror type small-diameter parabolic antenna device is a small, small-diameter main reflector (parabolic reflector).
11 and a small, small-aperture sub-reflector 12 placed near the focal point f of the main reflecting mirror 11 (slightly forward of the focal point f).
And a circular waveguide feeder 33 serving as a power supply unit disposed so as to open near the focal point f ′ of the sub-reflecting mirror 12. The circular waveguide feeder 33 has a tapered shape whose inner shape gradually spreads from the root to the tip, and the tip is open to transmit or receive an electromagnetic wave. However, the tapered shape spreading from the root to the tip is set to a small inclination that does not greatly affect the directivity.

The circular waveguide feeder 33 penetrates through the center of the main reflecting mirror 11 and the focal point f ′ of the sub-reflecting mirror 12.
It is preferable that the focal point f ′ is located slightly inside the opening 33 a of the circular waveguide feeder 33.

The other structure is the same as that of the first embodiment, and the same or corresponding parts are denoted by the same reference characters and description thereof will not be repeated.

According to the third embodiment, in addition to the operation and effect of the first embodiment, the inner shape of the circular waveguide feeder 33 extends from the root to the tip. Since the tapered shape gradually spreads, the deterioration of the VSWR can be suppressed and the characteristics can be improved.

Although the embodiments of the present invention have been described above, it is obvious to those skilled in the art that the present invention is not limited to the embodiments and various modifications and changes can be made within the scope of the claims. There will be.

[0059]

As described above, according to the present invention,
By setting the diameter and depth of the main reflecting mirror to be small, it is possible to realize a compact antenna apparatus for satellite broadcasting and satellite communication reception suitable for general home use. Further, by reducing the depth dimension of the antenna device and mounting a radome having a nearly flat shape having water repellency, it is possible to make the antenna device less susceptible to rainfall and snow. .

[Brief description of the drawings]

FIG. 1 is a side sectional view showing a whole configuration of a first embodiment of a double-reflection mirror type small-diameter parabolic antenna device according to the present invention.

FIG. 2 is a schematic configuration diagram illustrating a dimensional relationship of the first embodiment of FIG. 1;

FIG. 3 is an enlarged side sectional view of a primary radiator portion in the first embodiment.

FIG. 4 is a front view of a converter input side having a reception probe unit in the first embodiment.

FIG. 5 is a perspective view showing an example of the receiving probe unit.

FIG. 6 is a perspective view showing another example of the receiving probe unit.

FIG. 7 is an enlarged sectional view of a main part showing a fitting portion between the main reflector and the radome in the first embodiment.

FIG. 8 is a rear view of the radome.

FIG. 9 shows a ratio F / D of the focal length F and the diameter D of the main reflecting mirror,
5 is a graph showing a relationship between a projection amount S of a focal position f from an opening surface of a main reflecting mirror and a ratio S / D of the diameter D.

FIG. 10 shows the distance F between the focal position f of the main reflecting mirror and the focal position f ′ of the sub-reflecting mirror when the diameter D of the main reflecting mirror is set to 18λ.
-F 'and the aperture efficiency of the antenna are expressed by the diameter d of the sub-reflector.
Is a graph showing as a parameter.

FIG. 11 is a graph showing the relationship between the distance FF ′ and the antenna aperture efficiency when the diameter D of the main reflecting mirror is D = 22λ, using the diameter d of the sub-reflecting mirror as a parameter.

FIG. 12 is a side sectional view showing the entire configuration of the second embodiment of the present invention.

FIG. 13 is a schematic configuration diagram illustrating a dimensional relationship of the second embodiment in FIG. 12;

FIG. 14 is an enlarged side sectional view of a primary radiator in the second embodiment.

FIG. 15 is a side sectional view showing the entire configuration of the third embodiment of the present invention.

FIG. 16 shows a conventional double-reflection mirror type parabolic antenna device 1
It is a side sectional view showing an example.

[Explanation of symbols]

 1,11 Main reflector 2,12 Sub reflector 3 Stay 4,13,23,33 Waveguide feeder 5,30 Radome 11a Center hole 11b Flange part 13b, 23b Male screw 14 Converter 14b Female screw 15 Base member 16 Fidome 17, 18 Waterproof parts 20 Receiving probe part 20a, 20b Orthogonal probe 21 Circular waveguide part 30a Circular fitting part 30b Locking convex part 31 Elastic molding

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-299302 (JP, A) JP-A-59-139706 (JP, A) JP-A-58-64809 (JP, A) 82056 (JP, A) JP-A-6-204905 (JP, A) JP-A-6-90111 (JP, A) JP-A-58-3339 (JP, A) Japanese Utility Model Laid-Open No. 60-101808 (JP, U) Japanese Utility Model Showa 54-55247 (JP, U) Japanese Utility Model Showa 54-135841 (JP, U) Japanese Utility Model Showa 58-28416 (JP, U) Japanese Utility Model Showa 53-48544 (JP, U) Japanese Utility Model Showa 60-189104 (JP, U) Special Table Hei 1-500790 (JP, A) (58) Fields surveyed (Int. Cl. ⁷ , DB name) H01Q 15/00-19/12 H01Q 1/02-1/42

Claims (7)

(57) [Claims] 1. A small main reflector having a parabolic surface, a small sub-reflector having a hyperboloid located near the focal point of the main reflector, and a tip located near the focal point of the sub-mirror. And a converter connected to the circular waveguide, wherein the diameter of the main reflecting mirror is D and the diameter of the sub-reflecting mirror is D. d, the focal length of the main reflector is F, the distance from the center of the main reflector to the focal point of the sub-reflector is F ', the distance between the focal position of the main reflector and the focal position of the sub-reflector To F
−F ′, where λ is the wavelength of the electromagnetic wave, 0.25 ≦ F / D ≦ 0.30 18λ ≦ D ≦ 22λ 2λ ≦ d ≦ 3λ 1.0λ ≦ FF ′ ≦ 1.5λ Characteristic double-reflection mirror type small-diameter parabolic antenna device. 2. The sub-reflector and the distal end of the circular waveguide are connected to each other through a low-permittivity synthetic resin hollow structure, and the sub-reflector is positioned at a predetermined position by the hollow structure. 2. The double-reflection mirror type according to claim 1, wherein said sub-reflector and said hollow structure and said circular waveguide and said hollow structure are water-tightly joined and integrated using elastic waterproof means. A small-diameter parabolic antenna device. 3. The circular waveguide has a straight pipe whose inner shape is the same diameter from the root to the tip, and connection between the circular waveguide and the converter is made by screwing with a screw, and is detachable. 3. The double-reflection mirror type small-diameter parabolic antenna device according to claim 1, which is freely movable. 4. The circular waveguide is a straight pipe whose inner shape is the same diameter from the root to the vicinity of the tip,
3. The double-reflecting mirror type according to claim 1, wherein the horn-like shape has a tapered tip only, and the connection between the circular waveguide and the converter is detachable by screwing with screws. A small-diameter parabolic antenna device. 5. The circular waveguide has a tapered shape whose inner shape gradually expands from the root to the tip, and the connection between the circular waveguide and the converter is made by a screw. 2. A screw connection and detachable connection.
Or a double-reflector-type small-diameter parabolic antenna device according to 2. Wherein said circular transmission mode of the waveguide is a TE _11, claim 1 and 2 input of the converter has a horizontal and vertical two orthogonal probes in circular waveguide structure,
6. The double-reflector-type small-diameter parabolic antenna device according to 3, 4, or 5. 7. An opening of the main reflecting mirror is covered with a radome having a water-repellent and almost flat shape together with the sub-reflecting mirror, and is elastic over an entire periphery of a flange formed at an opening edge of the main reflecting mirror. A molding is mounted, and a plurality of locking convex portions are formed inside the fitting portion of the radome that fits with the flange portion of the main reflecting mirror, and the fitting portion is attached to and detached from the outside of the elastic molding. 2. The flexible molding device according to claim 1, wherein the engaging convex portion is press-fitted and engaged with the elastic molding.
7. The double-reflection mirror type small-diameter parabolic antenna device according to 2, 3, 4, 5, or 6.