JP3311857B2 - 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 circularly or linearly polarized parabolic antenna used for microwave communication such as reception of satellite broadcasting, and more particularly to a coaxial cable to which a primary radiator is connected. The present invention relates to improvement of a stay structure for reinforcement.

[0002]

2. Description of the Related Art Japanese Patent Publication No. Hei 5-4327 proposed by the present applicant discloses a coaxial cable connected to a primary radiator in a center-feed type parabolic antenna apparatus having directivity in the direction of the central axis of a parabolic reflector. It is disclosed that the stay for reinforcing the metal is made of a metal or a member having at least an outer surface having conductivity.

FIG. 14 shows a conventional center-feed type parabolic antenna apparatus having a stay structure as proposed in Japanese Utility Model Publication No. 5-4327. In this figure, a primary radiator (backfire helical antenna) 2 is disposed near a focal point of a parabolic reflector (parabolic reflector) 1, and a coaxial cable ( (For example, semi-rigid cable, rigid cable, etc.)
3 is connected and is drawn behind the reflector on the central axis of the reflector. Around the coaxial cable 3, a cylindrical stay 4 having at least an outer surface that is conductive is provided. A mounting base 5 is fixed to the back surface of the reflecting mirror 1 with screws or the like, and a converter (BS or CS converter) 6 is fixed on the mounting base. The leading end of the coaxial cable 3 is inserted and supported by a coaxial-waveguide converter 7 integrated with the converter 6, and the base of the stay 4 is fixed to the coaxial-waveguide converter 7. That is, the stay 4 is fixed to the reflecting mirror 1 side, and covers and protects the coaxial cable 3 and mechanically reinforces it to prevent the coaxial cable 3 from bending and vibration. In addition, a mounting bracket 8 for mounting the apparatus to the antenna mast is connected to the mounting base 5.

[0004]

By the way, in the above-described parabolic antenna apparatus of FIG. 14, the primary radiator 2 supports and strengthens the coaxial cable 3 provided with the primary radiator 2 at the tip by the stay 4 having at least the outer surface having conductivity. The electromagnetic wave is totally reflected on the stay surface, and the original directional characteristics and VSW
R is not compromised.

However, in order to embody the stay 4 having at least an outer surface having conductivity, the manufacturing is complicated and the cost is increased for the following reasons.

(1) When the stay is made of metal, the surface of the stay must be coated with a material that does not rust or a material that does not easily rust the metal itself must be used for weather resistance. It also takes time to perform taper processing during manufacturing.

(2) When the stay is made of resin, at least the outer surface must have a structure having conductivity. For example, the surface is plated with a conductive material, a conductive paint is applied, and Must be mixed with a conductive material.

If this stay is formed only of a resin such as polycarbonate, acrylic, or nylon, and injection molding is performed, the metal stay and the outer surface of the above (1) and (2) can be manufactured more easily than the conductive stay. It is clear that the cost will be reduced. However, as described in Japanese Utility Model Publication No. 5-4327, if the stay is made of resin without any consideration, the electric field component of the electromagnetic wave converges due to the dielectric properties of the resin, and the primary radiator has The main lobe is thinned or disturbed, and the VSWR characteristic is also deteriorated.

In view of the above, the present invention provides a parabolic antenna device capable of reinforcing a coaxial cable to which a primary radiator is connected without impairing various electrical characteristics (radiation patterns, VSWR characteristics, etc.). The purpose is to provide.

[0010]

In order to achieve the above object, the present invention provides a reflector and a backfire helical antenna or a backfire zigzag as a primary radiator disposed near a focal point of the reflector. In a center-feed type parabolic antenna device having an antenna and a coaxial cable for supplying power to the primary radiator, provided around the coaxial cable to reinforce the coaxial cable connected to the primary radiator. The stay is made of a non-conductive resin, and has an average thickness of 0.08λ or less over at least 2.5λ (λ: wavelength of electromagnetic wave) or more from the end of the coaxial cable.

[0011]

According to the center feed type parabolic antenna device of the present invention, the stay may be made of a resin having no conductivity, and can be efficiently manufactured by injection molding of a resin such as polycarbonate, acrylic, nylon, etc. Cost can be reduced. In the vicinity of the primary radiator where the electric field intensity of the electromagnetic wave is strong, that is, in the range of at least 2.5λ (λ: wavelength of the electromagnetic wave to be used) from the end of the coaxial cable, the thickness of the resin forming the stay is sufficiently thin. By doing so, it is possible to prevent deterioration of various electrical characteristics (for example, disturbance of directivity characteristics, that is, disturbance of radiation patterns, deterioration of VSWR characteristics, etc.) due to the properties of the resin as a dielectric.

The average thickness of the resin is 0.08λ over at least 2.5λ from the end of the coaxial cable.
By doing so, the deterioration of various electrical characteristics due to the properties of the resin as a dielectric is substantially eliminated, and the same performance as a metal stay or a stay whose outer surface is conductive can be secured.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a parabolic antenna device according to the present invention will be described below with reference to the drawings.

A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows the overall configuration of the first embodiment, and FIGS. 2 and 3 show a backfire helical antenna 10 as a primary radiator for circularly polarized waves, a coaxial cable 3 connected thereto, and a resin having no conductivity. A coaxial-waveguide converter 7 integrally fixed to a stay 20 and a converter 6 made of
4 and 5 show the stay 20. FIG.

In these figures, a backfire helical antenna 10 as a primary radiator is disposed near the focal point of a parabolic reflector (parabolic reflector) 1, and the backfire helical antenna 10 is located on the reflector side of the reflector. A coaxial cable (for example, a semi-rigid cable or a rigid cable) 3 is connected to the feeding point. That is, the backfire helical antenna 10 is
One and one spiral conductor 12 are provided. As shown in FIG. 2, the matching disk 11 is connected to the outer periphery of the outer conductor 3A of the coaxial cable 3 and the spiral conductor 12 is connected to the center conductor 3B. Is done.

A cylindrical stay 20 made of a non-conductive resin is provided around the coaxial cable 3. The cylindrical stay 20 is made by injection molding of a resin such as polycarbonate, acrylic, nylon, or the like, and has a small diameter that circumscribes the distal end of the coaxial cable 3 and holds the coaxial cable 3 as shown in FIGS. Cable holding portion 21, a tapered portion 22 whose outer diameter decreases from the base to the tip, and a fitting portion 23 formed on the inner periphery of the base.
And The thickness of the resin is 2 mm or less (12 GHz) in a range of length L (L is 50 mm or more, which is 2λ or more when converted to a wavelength of 12 GHz which is a frequency of satellite broadcasting used as a frequency used) from the tip of the tapered portion 22. (Converted to a wavelength of 0.08λ or less). The dimension between the tip of the coaxial cable 3 (the position of the matching disk 11) and the tip of the tapered portion 22 of the stay 20 is equal to 0.1.
Since it is about 5λ, considering the tip of the coaxial cable 3 as a reference, the thickness of the resin is 0.08λ or less over a length Lo of 2.5λ or more from the tip of the coaxial cable 3. However, in order to maintain the function of the stay as an original reinforcing part, the constant thickness part of the dimension L is 0.5 mm.
(More than 0.02λ when converted to a wavelength of 12 GHz)
Thickness is required. In this embodiment, for example, the length L can be set to 50 mm and the thickness can be set to 1 mm.
2 and 4, the base side of the tapered portion 22 is 2 mm.
It may be the above. As shown in the cross-sectional view of FIG. 6, the range of the length dimension L of the tapered portion 22 is a uniform thickness. Also, the cable holding part 21 is 0.02λ to 0.2λ.
It is desirable that the thickness be 08λ.

The base of the coaxial cable 3 is a converter 6
Center hole 7 of cylindrical portion 7A of coaxial-waveguide converter 7 fixed to
B, and a cylindrical stay 2 is mounted on the outer periphery of the cylindrical portion 7A.
The fitting part 23 of the base part of No. 0 is fitted and fixed. Since the converter 6 and the coaxial-waveguide converter 7 are fixed to the mounting base 5 on the back of the reflecting mirror 1, the cylindrical stay 20 is eventually supported and fixed to the reflecting mirror 1 side. Backfire helical antenna 1
0 covers and protects the connected coaxial cable 3 and mechanically reinforces it to prevent the coaxial cable 3 from being bent or vibrated.

A fidome 30 of a low dielectric constant resin or the like that covers the backfire helical antenna 10 is connected and fixed to the cable holding portion 21 at the distal end of the cylindrical stay 20, and a metal cap 31 is attached to the distal end of the fidome 30. Fitted and fixed. The fidome 30 protects the backfire helical antenna 10 from rainwater, and the metal cap 31 functions as a reflector to improve the FB ratio of the primary radiator and improve the antenna gain. Other configurations are the same as those of the conventional example of FIG.

FIG. 7 shows the relationship between the thickness (mm) of the cylindrical stay at a frequency of 12 GHz (constant thickness over the entire length) and the gain reduction (dB) of the parabolic antenna apparatus. In the case of the metal stay, the gain reduction is zero irrespective of the wall thickness, but in the case of the resin stay, the gain reduction is zero to small when the wall thickness is 2 mm or less (when converted to a wavelength of 12 GHz and 0.08λ or less). However, it can be seen that when it exceeds 2 mm, the decrease in gain increases rapidly and cannot be ignored.

FIG. 8 shows a dimension L of a portion having a constant thickness from the tip of the tapered portion 22 of the cylindrical stay 20 at a frequency of 12 GHz and a decrease in the gain of the parabolic antenna device (dB).
(However, the length from the end of the coaxial cable to the end of the tapered portion 22 is 12.5 mm and 12
It is 0.5λ when converted to a wavelength of GHz). In this figure, in the case of the metal stay, the gain reduction is zero irrespective of the thickness, but the constant thickness range of the dimension L of the solid line (A) is 1 thickness.
When the dimension L is less than 50 mm, the gain decreases rapidly and cannot be neglected in the case where the dimension L is less than 50 mm. Dimension L of constant thickness part
Is 50 mm or more (2λ or more when converted to a wavelength of 12 GHz), the gain reduction is substantially zero to minute.
As shown in FIG. 8, the property of the resin stay 20 affects the characteristics in the vicinity of the backfire helical antenna 10 as the primary radiator. The strength can be supplemented by forming the portion on the stay tip side and increasing the thickness of the other portions.

According to the first embodiment, the following effects can be obtained.

(1) The parabolic antenna apparatus of this embodiment is of a center feed type, and an electromagnetic wave incident parallel to the central axis of the parabolic reflector 1 is reflected by the parabolic reflector 1 and reflected therefrom. Converges to the focal point,
The light enters from the feeding point side of the helical antenna 10. At this time, since the backfire helical antenna 10 has the main lobe on the feed point side, the electromagnetic wave reflected by the reflector 1 is efficiently received by the backfire helical antenna 10. In this case, the cylindrical stay 20 is made of a resin having no conductivity, but is close to the backfire helical antenna 10 and has a large length L from the tip of the tapered portion 22 (L is 50 mm).
As described above, the range of 2 GHz or more when converted to a wavelength of 12 GHz which is the frequency of satellite broadcasting is set to a thickness of 2 mm or less (12 GHz).
By setting the wall thickness to a constant value of 0.08λ or less when converted to a wavelength, the inconvenience caused by the cylindrical stay 20 being a resin, that is, disturbance of the radiation pattern, deterioration of the VSWR characteristic, and the like can be prevented. The performance substantially equivalent to that of the manufacturing stay can be secured.

When the tip of the coaxial cable 3 is used as a reference, the thickness of the resin is 0.08λ or less over a length Lo of 2.5λ or more from the tip of the coaxial cable 3.

(2) Tapered portion 22 of cylindrical stay 20
The range of the length dimension L from the tip of is a thin constant thickness,
Since the portion of the tapered portion 22 near the base has little effect on the antenna characteristics, the thickness can be increased and sufficient mechanical strength can be obtained.

(3) The cylindrical stay 20 can be easily manufactured by injection molding of a general resin having no conductivity, for example, polycarbonate, acrylic, nylon, or the like, so that the cost can be reduced.

In the first embodiment, as shown in the cross-sectional view of the tapered portion 22 of the cylindrical stay 20 in FIG. 6, the case where the thickness of the cross-section of the tapered portion 22 is constant is illustrated. As shown in the modified example of FIG. 9 or FIG. 10, ribs 25 and 26 having a large thickness are partially formed on the inner periphery of the tapered portion 22 of the resin-made cylindrical stay 20 having no conductivity in the longitudinal direction of the stay. Alternatively, mechanical strength may be ensured.
FIG. 9 shows a rib 25 having a small width but a large height and a tapered portion 2.
FIG. 10 shows an example in which a rib 26 having a large width but a low height is formed on the inner periphery of the tapered portion 22. In these cases, the average thickness T in the cross section indicated by the imaginary line in the figure is set to 0.08λ similarly to the case of the first embodiment.
The same effect as in the first embodiment can be obtained by setting 0.02λ or more below.

FIG. 11 shows a second embodiment of the present invention. In the second embodiment, a cylindrical stay 40 whose outer diameter changes stepwise is used. That is, the resin-made cylindrical stay 40 having no conductivity is a small-diameter cable holding portion 41 that circumscribes the distal end portion of the coaxial cable 3 and holds the coaxial cable 3.
A small-diameter portion 42 having a constant thickness, a large-diameter portion 43, and a fitting portion 44 formed on the inner periphery of the base of the large-diameter portion 43.
And The length L of the small diameter portion 42 is 5
0mm or more (1 which is the frequency of satellite broadcasting used
2λ or more when converted to a wavelength of 2 GHz), and the thickness is 2 mm.
(Less than 0.08λ when converted to a wavelength of 12 GHz)
Is formed to a constant thickness. However, in order to maintain the original function of the stay, the constant thickness portion of the dimension L needs to have a thickness of 0.5 mm or more (0.02λ or more when converted to a wavelength of 12 GHz). As shown in FIG. 11, the large diameter portion 43 may have a thickness of 2 mm or more to secure mechanical strength. 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 will be omitted.

Also in the case of the second embodiment, the coaxial cable 3
Is 2.5λ from the distal end of the to the base end of the small diameter portion 42.
As described above, substantially the same operation and effect as those of the first embodiment can be obtained.

FIG. 12 shows a third embodiment of the present invention. In the third embodiment, a cylindrical stay 50 having the same outer diameter and integrally having a fidome is used. That is, the resin cylindrical stay 50 having no conductivity has a constant thickness over the entire length, and the thickness is set to 0.08λ or less and 0.02λ or more. A metal plate 51 acting as a reflector is fixed in advance to the inside of the closed end face of the cylindrical stay 50, and the base of the cylindrical stay 50 is fitted and fixed to the coaxial-waveguide converter 7 fixed to the converter. Is done. The backfire helical antenna 10 and the coaxial cable 3 connected thereto are covered with a cylindrical stay 50, and the coaxial cable 3
Is supported inside the cylindrical stay 50 by a spacer 52 having a low dielectric constant and a small thickness. Other configurations may be the same as those of the first embodiment.

In the stay 50 of the third embodiment,
It is necessary to set the wall thickness between 0.02λ and 0.08λ because of the surroundings of the backfire helical antenna 10 corresponding to a fidome and 2.5λ from the end of the coaxial cable.
And the thickness of the stay base side may be increased.

In the case of the third embodiment, the fidome portion covering the backfire helical antenna 10 can be integrally formed with the stay portion, so that the structure can be simplified and the number of assembling steps can be reduced, and the cost can be further increased. Reduction can be made possible.

FIG. 13 shows a fourth embodiment of the present invention. In this case, a backfire zigzag antenna 60 suitable for transmitting and receiving linearly polarized waves is used as a primary radiator, and is connected to the end of the coaxial cable 3. That is, the backfire zigzag antenna 60 has a director 61 and a zigzag conductor 62. The director 61 is connected to the outer periphery of the distal end of the outer conductor 3A of the coaxial cable 3, and the zigzag conductor 62 is connected to the center conductor 3B. Connected to. The configuration other than the primary radiator may be the same as that of the above-described first embodiment, and the same or corresponding portions are denoted by the same reference characters and description thereof will be omitted.

According to the fourth embodiment, even when transmitting and receiving linearly polarized waves, the coaxial cable 3 is supported by the non-conductive resin cylindrical stay 20 whose shape and structure are devised, so that the metal stay The same level of performance can be secured.

As a primary radiator of the first to third embodiments, a backfire zigzag antenna suitable for linearly polarized wave transmission and reception may be used instead of a backfire helical antenna suitable for circularly polarized wave transmission and reception. Good.

The metal cap 31 in the first embodiment
May be a resin cap, and the metal plate 5 of the third embodiment
1 can also be omitted.

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. Would.

[0037]

As described above, according to the parabolic antenna apparatus of the present invention, a backfire helical antenna or a backfire zigzag antenna as a primary radiator can be connected without impairing various electrical characteristics. The coaxial cable can be reinforced by the resin stay, and the resin stay does not need to have conductivity, so that the stay can be easily manufactured and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a side sectional view of a first embodiment of a parabolic antenna device according to the present invention.

FIG. 2 is a side sectional view showing the stay and its peripheral structure.

FIG. 3 is a plan view of the same.

FIG. 4 is a side sectional view of the stay.

FIG. 5 is a front view of the same.

FIG. 6 is a transverse sectional view of the same.

FIG. 7 is a graph showing a change in gain of the entire parabolic antenna device due to a difference in thickness of a tapered portion of a resin stay.

FIG. 8 shows a constant thickness (1 mm) of the tapered portion of the resin stay.
Or 2 mm) is a graph showing a change in gain of the entire parabolic antenna device due to a difference in the length of the constant thickness portion.

FIG. 9 is a cross-sectional view showing a modification of a stay that can be employed in the embodiment of the present invention.

FIG. 10 is a cross-sectional view showing another modification of the stay that can be employed in the embodiment of the present invention.

FIG. 11 is a side sectional view showing a main part of a second embodiment of the present invention.

FIG. 12 is a sectional side view of a main part showing a third embodiment of the present invention.

FIG. 13 is a side sectional view showing a main part of a fourth embodiment of the present invention.

FIG. 14 is a side sectional view of a conventional parabolic antenna device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Parabolic reflector 2 Primary radiator 3 Coaxial cable 4, 20, 40, 50 Cylindrical stay 5 Mounting pedestal 6 Converter 7 Coaxial-waveguide converter 10 Backfire / helical antenna 21, 41 Cable holding part 22 Taper Part 23, 44 Fitting part 30 Fidome 31 Metal cap 42 Small diameter part 43 Large diameter part 60 Backfire / zigzag antenna

Continuation of the front page (56) References JP-A-63-194403 (JP, A) JP-A-61-161809 (JP, A) JP-A-5-121928 (JP, A) JP-A-2-89404 (JP) JP-A-5-59929 (JP, A) JP-A-5-59928 (JP, U) JP-A-6-9219 (JP, U) JP-A-6-13212 (JP, U) 39-15157 (JP, B1) Jikken Hei 5-4327 (JP, Y2) (58) Field surveyed (Int. Cl. ⁷ , DB name) H01Q 19/15 H01Q 11/08

Claims (1)

(57) [Claims] 1. A reflecting mirror, a backfire helical antenna or a backfire zigzag antenna serving as a primary radiator disposed near a focal point of the reflecting mirror, and a coaxial cable for feeding the primary radiator. In the center-feed type parabolic antenna device having, a stay provided around the coaxial cable to reinforce the coaxial cable connected to the primary radiator is formed of a resin having no conductivity, and the coaxial A parabolic antenna device wherein the resin has an average thickness of 0.08λ or less over at least 2.5λ (λ: wavelength of electromagnetic wave) from the end of the cable.