JP3964129B2 - Antenna device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an antenna device for satellite communication, for example.
[0002]
[Prior art]
A conventional antenna device will be described with reference to the drawings. FIG. 3 is a perspective view showing a configuration of a conventional antenna device disclosed in, for example, Japanese Patent Laid-Open No. 8-078945, and FIG. 4 is a partially developed view of the flexible substrate in FIG.
[0003]
3 and 4, 1 is an antenna conductor, 4 is a coaxial cable, 10 is a dielectric cylinder, 11 is a flexible substrate, 12 is a balun, 13 is a metal conductor, and 14 is a double-sided adhesive tape.
[0004]
Next, the operation of the conventional antenna device will be described with reference to the drawings.
[0005]
A flexible substrate 11 having an antenna conductor 1 is wound around a surface of a dielectric cylinder 10 by a double-sided adhesive tape 14 and stretched. The antenna conductor 1 is fed by a coaxial cable 4 through a balun 12.
[0006]
The metal conductor 13 plays a role of adjusting the phase of the reflected wave from the end of the antenna conductor of the antenna device to achieve electrical matching. The metal conductor 13 has a bent structure for the necessity of electrical matching. The electrical matching can be performed relatively easily by shifting the bent portion.
[0007]
[Problems to be solved by the invention]
In the conventional antenna device as described above, the metal conductor 13 must be fixed to the antenna conductor 1 in order to achieve electrical matching, and there is a problem that the number of parts increases.
[0008]
The metal conductor 13 is used to adjust the phase of the reflected wave from the end of the antenna conductor for matching, but this reflected wave causes a back lobe in an antenna having an axially symmetric and balanced two-wire shape. . When this back lobe occurs, there is a problem that the gain of the positive beam is lowered.
[0009]
The present invention has been made to solve the above-mentioned problems, and it is possible to achieve electrical matching by combining the antenna conductor shape and the balun with a simple configuration without increasing the number of parts for matching. An object of the present invention is to obtain an antenna device capable of obtaining desired radiation characteristics by selecting an arbitrary antenna diameter (φ) without being troubled by a matching problem.
[0010]
[Means for Solving the Problems]
An antenna device according to a first aspect of the present invention includes a cylindrical dielectric annular support base that is long in one direction, a center conductor, and an outer conductor, and the longitudinal direction inside the cylindrical dielectric annular support base. A coaxial cable provided at the center of the cylindrical dielectric ring, and a circular ceiling mounted on the upper end of the cylindrical dielectric ring-shaped support base and provided with a hole having the same size as the diameter of the coaxial cable at the center. A strip having a width equal to one-fourth of the circumference of the cylindrical dielectric annular support base, which is spirally wound 180 degrees facing the surface of the longitudinal side surface of the dielectric annular support base. The first and second antenna conductors are provided on the top plate so as to be opposed to each other by 180 degrees, and the sector-shaped third and fourth antenna conductors having a quarter shape of a circle, the fourth antenna conductors, Short-circuit piece for electrically connecting antenna conductor and central conductor at upper end of coaxial cable The strip-shaped first antenna conductor and the fan-shaped third antenna conductor are coupled on the outer periphery of the circular top plate, and the strip-shaped second antenna on the outer periphery of the circular top plate. A conductor and the fan-shaped fourth antenna conductor are coupled, and the outer conductor at the upper end of the coaxial cable is electrically connected to the third and fourth antenna conductors, and is connected to the outer conductor at the upper end of the coaxial cable. A split balun that performs balanced-unbalanced conversion is configured by inserting two slits with a length of 1/4 wavelength facing each other by 180 degrees.
[0011]
In the antenna device according to claim 2 of the present invention, when the strip-shaped first and second antenna conductors are rotated 90 degrees along the central axis of the antenna, the shapes of the conductor portion and the non-conductor portion coincide with each other. When the fan-shaped third and fourth antenna conductors are rotated by 90 degrees along the central axis of the antenna, the shapes of the conductor part and the non-conductor part coincide with each other.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
An antenna apparatus according to Embodiment 1 of the present invention will be described with reference to the drawings. 1 is a perspective view showing a configuration of an antenna apparatus according to Embodiment 1 of the present invention. In addition, in each figure, the same code | symbol shows the same or equivalent part.
[0013]
In FIG. 1, 1 is an antenna conductor having a structure in which the shape of the conductor portion is air when rotated 90 ° along the central axis of the antenna, and 2 is a cylindrical dielectric ring that supports the antenna conductor 1. A support base, 4 is a coaxial cable, 5 is a short-circuit piece (conductor) for connecting a center conductor (to be described later) of the coaxial cable 4 and the antenna conductor 1, and 9 is a top plate on the top of the dielectric annular support base 2.
[0014]
That is, two antenna conductors 1 having the same width as ¼ of the circumference of the dielectric annular support 2 are spirally wound around the surface of the side surface of the cylindrical dielectric annular support 2. Further, two antenna conductors 1 having a shape of a quarter of a circle are provided on the top plate 9, and are coupled to the antenna conductor 1 provided on the side surface of the dielectric annular support base 2.
[0015]
FIG. 2 is an enlarged perspective view showing the upper part of the antenna device shown in FIG. 1 in an enlarged manner, and the illustration of the antenna conductor provided on the side surface of the dielectric annular support base is omitted.
[0016]
In FIG. 2, 3 is a split balun having a length of approximately λ / 4 (λ: 1 wavelength), 5 is a short-circuit piece, 7 is a central conductor of the coaxial cable 4, and 8 is an outer conductor of the coaxial cable 4.
[0017]
The central conductor 7 of the coaxial cable 4 is electrically connected to the antenna conductor 1b on the top plate 9 through the short-circuit piece 5, and the outer conductor 8 of the coaxial cable 4 is electrically connected to the antenna conductor 1a on the top plate 9. It is connected. The antenna conductor 1b on the top plate 9 is also connected to the outer conductor 8 of the coaxial cable 4.
[0018]
Next, the operation of the antenna device according to the first embodiment will be described with reference to the drawings.
[0019]
The split balun 3 shown in FIG. 2 performs balance-unbalance conversion by inserting a slit having a length of approximately λ / 4 in the outer conductor 8 of the coaxial cable 4. The split balun 3 operates as a transformer having an impedance transformation ratio of approximately 1: 4, and when a general 50Ω cable is used as the coaxial cable 4, the matching impedance of the split balun 3 is approximately 200Ω.
[0020]
The input impedance of the antenna having an axisymmetric and balanced two-wire shape is such that the shape of the antenna conductor 1 wound around the dielectric annular support base 2 and the antenna conductors 1a and 1b on the top plate 9 is generally self-complementary. Therefore, it is generally 60π = 188.5Ω regardless of the antenna diameter φ. For this reason, it is excellent in electrical matching with the split balun 3. Further, since matching is obtained with any antenna diameter φ, desired radiation characteristics can be obtained. This is because the radiation efficiency is changed by changing the antenna diameter φ, and the radiation characteristics such as the beam width are changed accordingly.
[0021]
As described above, when the antenna portion is rotated by 90 ° along the central axis of the antenna, the shape of the conductor portion is the same as that of the air, that is, the antenna conductor 1 (helical conductor) having a substantially self-complementary shape. The structure having the split balun 3 that performs a balanced-unbalanced conversion having a slit of approximately λ / 4 in length is excellent in electrical matching, and a desired radiation characteristic can be obtained with any antenna diameter φ.
[0022]
That is, the antenna device according to the first embodiment is formed in a cylindrical shape that is long in one direction and extends in the longitudinal direction of the dielectric annular support base 2 made of a non-conductive material and the dielectric annular support base 2. The two antenna conductors 1 are arranged on the top plate 9 and are arranged so that the shape of the conductor portion and the air is approximately the same when rotated 90 ° along the central axis of the antenna. And two antenna conductors 1a and 1b having a structure in which the shape of the conductor portion is substantially the same when rotated by 90 ° along the central axis of the antenna, and the length is approximately λ / 4 (λ And split balun 3 that performs balanced-unbalanced conversion having two slits of 1 wavelength).
[0023]
【The invention's effect】
As described above, the antenna device according to claim 1 of the present invention includes a cylindrical dielectric annular support base that is long in one direction, a center conductor, and an outer conductor. A coaxial cable provided at the center in the longitudinal direction of the inside and placed at the upper end of the cylindrical dielectric annular support base, and a hole having the same size as the diameter of the coaxial cable is provided at the center. A circular top plate and a spirally wound surface facing the surface of the longitudinal side surface of the dielectric ring-shaped support base 180 degrees, and 1/4 of the circumference of the cylindrical dielectric ring-shaped support base A strip-shaped first and second antenna conductors having the same width as those of the fan-shaped third and fourth antenna conductors, which are provided on the top plate so as to face each other by 180 degrees and have a quarter shape of a circle; The fourth antenna conductor and the central conductor at the upper end of the coaxial cable are electrically connected. The strip-shaped first antenna conductor and the fan-shaped third antenna conductor are coupled on the outer periphery of the circular top plate, and the outer periphery of the circular top plate A strip-shaped second antenna conductor and the sector-shaped fourth antenna conductor are coupled, and an outer conductor at the upper end of the coaxial cable is electrically connected to the third and fourth antenna conductors, and the coaxial A split balun that performs balanced-unbalanced conversion is configured by inserting two slits with a length of 1/4 wavelength facing the outer conductor at the upper end of the cable at 180 degrees. However, there is an effect that desired radiation characteristics can be obtained.
[0024]
As described above, when the strip-shaped first and second antenna conductors are rotated by 90 degrees along the central axis of the antenna, the antenna device according to claim 2 of the present invention has a conductor portion and a non-conductor. And the fan-shaped third and fourth antenna conductors are rotated 90 degrees along the center axis of the antenna so that the shapes of the conductor part and the non-conductor part match. Therefore, it is excellent in electrical matching with a normal coaxial cable, and there is an effect that a desired radiation characteristic can be obtained with any antenna diameter.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a configuration of an antenna apparatus according to Embodiment 1 of the present invention.
FIG. 2 is an enlarged perspective view showing an enlarged configuration of an upper part of the antenna device according to the first embodiment of the present invention.
FIG. 3 is a perspective view showing a configuration of a conventional antenna device.
4 is a diagram showing a state where a part of the flexible substrate in FIG. 3 is developed.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Antenna conductor, 2 dielectric annular support stand, 3 split balun, 4 coaxial cable, 5 short piece, 7 center conductor, 8 outer conductor, 9 top plate.

Claims (2)

A cylindrical dielectric annular support that is long in one direction;
A coaxial cable composed of a center conductor and an outer conductor, provided at the center in the longitudinal direction inside the cylindrical dielectric annular support base,
A circular top plate placed on the upper end of the cylindrical dielectric ring-shaped support base and having a hole of the same size as the diameter of the coaxial cable in the center;
A strip-shaped first ring having a width equal to one-fourth of the circumference of the cylindrical dielectric ring-shaped support base is spirally wound 180 degrees on the surface of the side surface in the longitudinal direction of the dielectric ring-shaped support base. A first and second antenna conductor;
The fan-shaped third and fourth antenna conductors, which are provided on the top plate so as to face each other by 180 degrees and have a quarter shape of a circle,
A short-circuit piece for electrically connecting the fourth antenna conductor and the central conductor at the upper end of the coaxial cable;
The strip-shaped first antenna conductor and the fan-shaped third antenna conductor are coupled on the outer periphery of the circular top plate, and the strip-shaped second antenna conductor on the outer periphery of the circular top plate A fan-shaped fourth antenna conductor is coupled,
The outer conductor at the upper end of the coaxial cable is electrically connected to the third and fourth antenna conductors,
An antenna device that constitutes a split balun that performs balanced-unbalanced conversion by inserting two slits having a length of ¼ wavelength facing the outer conductor at the upper end of the coaxial cable at 180 degrees. The strip-shaped first and second antenna conductors have a structure in which the shapes of the conductor part and the non-conductor part coincide when rotated 90 degrees along the central axis of the antenna,
The fan-shaped third and fourth antenna conductors have a structure in which the shapes of the conductor portion and the non-conductor portion coincide when rotated 90 degrees along the central axis of the antenna. The antenna device described.

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