JP4154557B2 - Antenna device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is a digital radio capable of listening to a digital radio broadcast by receiving radio waves from an artificial satellite (hereinafter also referred to as “satellite waves”) or radio waves on the ground (hereinafter also referred to as “terrestrial waves”). It belongs to the antenna device used for the receiver.
[0002]
[Prior art]
Recently, digital radio receivers that receive radio waves (satellite waves) or terrestrial waves from artificial satellites and that can listen to digital radio broadcasts have been developed and are being put to practical use in the United States.
[0003]
This digital radio receiver is mounted on a mobile station such as an automobile, and can receive radio waves by receiving radio waves having a frequency of about 2.3 GHz. That is, the digital radio receiver is a radio receiver capable of listening to mobile broadcasts. The terrestrial wave is obtained by slightly shifting the frequency after the satellite wave is once received by the earth station.
[0004]
In order to receive such a radio wave having a frequency of about 2.3 GHz, it is necessary to install an antenna outside the vehicle. As such an antenna, antennas having various structures are conceivable, but a stick type is generally used instead of a flat type (flat plate type).
[0005]
As is well known, an electromagnetic wave radiated to free space is a transverse wave having an electric field and a magnetic field that oscillate in a plane perpendicular to the traveling direction of the wave, and the strength of the electric field and the magnetic field changes in the plane. However, this is called polarization. Satellite waves are circularly polarized while terrestrial waves are linearly polarized.
[0006]
The antenna apparatus shown in FIG. 7 includes a columnar helical antenna (hereinafter referred to as an antenna) 21 for receiving satellite waves, a case 23 that supports the antenna 21 in an upright state, and an antenna 21. while standing, and a ground plate 31 installed part 25 to set only a conductive case 23 for installing the casing 23, and a cable 33 for supplying a power supply voltage.
[0007]
Ground plate 31, as shown in FIG. 8, a flat plate shape to be installed large and in a direction perpendicular to the axial direction than the cross-sectional shape of the antenna 21 definitive in a direction orthogonal to the uniaxial X parallel uniaxial X direction Presents. The ground plate 31 is employed to maintain the sensitivity of radio waves received by the antenna 21.
[0008]
That is, the antenna 21 receives a radio wave received from the front end side in the uniaxial direction of the antenna 21 (hereinafter referred to as the front side) and a setting unit 25 side (hereinafter referred to as the rear side) of the antenna 21. There are radio waves. It is desirable that these front-side and rear-side radio waves be less received on the rear side. Therefore, the sensitivity of the radio waves received by the antenna 21 increases as the ratio of the radio waves on the front side and the rear side increases.
[0009]
The satellite wave received by such an antenna 21 is combined in the phase by matching (adjusting) the phase by shifting the phase by a phase shifter, and then provided in the case 23. Amplified by a noise amplifier (LNA) and sent to the receiver body. Here, the combination of the antenna 21, the phase shifter, and the LNA is called an antenna device.
[Problems to be solved by the invention]
[0010]
As described above, in the conventional antenna device, the antenna 21 is erected on the case 23 to receive radio waves, and the radio waves received from the rear side are grounded by the flat ground plate. 21. However, since the ground plate has a flat plate shape, radio waves are received from the rear side of the antenna 21, and the ratio of the front side and the rear side is small. Cannot be reduced, and the antenna sensitivity cannot be improved.
[0011]
Therefore, an object of the present invention is to provide an antenna device that can greatly improve the ratio of the front side and the rear side of the antenna, reduce ground noise, and further improve antenna sensitivity.
[0012]
[Means for Solving the Problems]
According to the present invention , a columnar antenna (1) which is a helical antenna, a case (3) supporting the antenna (1), and a conductive ground plate (11 or 18 ) provided in the case (3). The case (3) includes a case part (4) that supports the antenna in a uniaxial (X) direction parallel to the uniaxial (X), and the case part ( 4) provided on the lower surface (4b) of the case portion (4) facing the upper surface (4a) so that the case (3) is installed in a state where the antenna (1) is erected from the upper surface (4a) of The case portion (4) and the installation portion (5) have a cross-sectional shape larger than the cross-sectional shape of the antenna orthogonal to the one axis (X) in the direction orthogonal to the one axis. And the ground plate (11 or 18) The installation portion having a cross-sectional shape larger than the outer periphery of the cross-sectional shape of the antenna orthogonal to the one axis (X) in a direction orthogonal to the axis and facing the lower surface (4b) of the case portion (4) ( 5) a flat main plate portion (11a) provided on the bottom surface (5a), and a position larger than the cross-sectional shape of the antenna (1) orthogonal to the one axis (X) from the main plate portion (11a). And the antenna apparatus which has the sub-plate part (11b) extended to the said lower surface (4b) side of the said case part (4) within the range of the said installation part (5) is obtained.
[0013]
In addition, the code | symbol in the said parenthesis is attached | subjected in order to make an understanding of this invention easy, and it is only an example, and of course is not limited to these.
[0014]
[Action]
The received radio wave is received by the antenna. The ground plate grounds radio waves received from the rear side by the main plate portion. Further, the sub-plate section, the ground causes the radio waves received toward from the periphery edge of the main plate portion to the antenna.
[0015]
As a result, the radio waves received from the rear side can be grounded by the main plate portion and the sub plate portion, so that the ratio of the front and rear side radio waves is increased and the sensitivity of the antenna is improved.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a first embodiment of an antenna device according to the present invention. 2 to 4 show the ground plate shown in FIG.
[0017]
Referring to FIG. 1, an antenna device according to a first embodiment of the present invention includes a columnar helical antenna (hereinafter referred to as an antenna) 1, a case 3 that supports the antenna 1 upright , And a conductive ground plate provided in the case 3 .
[0018]
The case 3 includes a case portion 4 that supports the antenna 1 erected in a uniaxial X direction parallel to the uniaxial X, and an upper surface 4a so that the case 3 is installed with the antenna 1 erected from the upper surface 4a of the case portion 4. And an installation portion 5 provided on the lower surface 4b of the case portion 4 facing each other. The case part 4 and the installation part 5 have a cross-sectional shape larger than the outer periphery of the cross-sectional shape of the antenna orthogonal to the uniaxial X in the direction orthogonal to the uniaxial X.
[0019]
As shown in FIGS. 2 to 4, the ground plate 11 has a cross-sectional shape larger than the cross-sectional shape of the antenna orthogonal to the single axis X in the direction orthogonal to the single axis X and faces the lower surface 4 b of the case portion 4. A plurality of plate-shaped main plate portions 11a provided on the bottom surface 5a of the installed portion 5 and extending toward the lower surface 4b side of the case portion 4 within the range of the installed portion 5 from the peripheral edge of the main plate portion 11a. And a sub-plate portion 11b.
[0020]
The ground plate 11 is formed with a plurality of holes 11c at predetermined locations, and is fixed to the installation portion 5 by passing screws through these holes 11c.
[0021]
The main plate portion 11a and the sub plate portion 11b are integrally formed by a single plate member, and a sub plate portion 11b shorter than one side of the main plate portion 11a is bent onto one surface of the main plate portion 11a. Has been. That is, the main plate portion 11a formed in the four places are flat exhibiting substantially square shown, sub-plate portion 11b are respectively songs folded onto one surface of the main plate portion 11a from Gerare four sides of the main plate portion 11a . Therefore, the sub-plate portion 11b in this embodiment is located at a position larger than the outer periphery of the cross-sectional shape of the antenna 1 orthogonal to the single axis X in the direction orthogonal to the single axis X from the main plate portion 11a within the range of the installation portion 5. The portion 4 extends to the lower surface 4b side. The case 3 is connected with a cable 13 for supplying a power supply voltage so as to be connected to the receiver body.
[0022]
The ground plate 11 is employed to maintain the sensitivity of radio waves received by the antenna 1. That is, the antenna 1 includes a radio wave received from the front end side in the uniaxial X direction of the antenna 1 (hereinafter referred to as the front side) and a lower end side in the uniaxial X direction of the antenna 1 (hereinafter referred to as the rear side). There are radio waves to be received . It is desirable that these front-side and rear-side radio waves be less received on the rear side. Therefore, the sensitivity of the radio waves received by the antenna 1 increases as the ratio of the radio waves on the front side and the rear side increases.
[0023]
In the antenna device according to a first exemplary embodiment, in the erected antenna 1 on the casing 3 is configured to receive a radio wave, the reception from the rear side by the main plate portion 11a of the flat plate of the ground plate 11 Ground the radio wave to be transmitted. Further, the sub-plate portion 11b, Ru is ground radio waves received toward from the periphery side of the main plate portion 11a to the antenna 1.
[0024]
As a result, radio waves received from the back side, it is possible to ground by the main plate portion 11a and the sub-plate portion 11b, the radio wave of the front side and the rear side reduces the ground noise because the ratio is increased, the antenna 1 sensitivity can be improved.
[0025]
The antenna 1 is an insulating cylinder or column member, for example, and has a structure in which a conductor is wound in a helix shape on the outer peripheral surface of a columnar member. An insulating material such as plastic is used as the material of the columnar member.
[0026]
As the conductor, one obtained by printing a plurality of conductor patterns on an insulating sheet or one obtained by winding a conductive linear member around a columnar member is adopted. In the helical antenna having such a structure, the resonance frequency is determined by the height (length), diameter, dielectric constant, and the like of the columnar member .
[0027]
The radio wave received by the conductor is synthesized by adjusting (adjusting) the phase by shifting the phase by a phase shifter (not shown) provided in the case 3, and then a low noise amplifier (not shown) LNA) is amplified and sent to the receiver body.
[0028]
FIG. 5 shows a second embodiment of the antenna device of the present invention. FIG. 6 shows a form before the ground plate shown in FIG. 5 is bent. In the second embodiment, since the antenna 1, the case 3, and the installation portion 5 of the case 1 of the first embodiment are employed, the same reference numerals are given to the descriptions thereof and the description is omitted. .
[0029]
5 and 6, the ground plate 18 has a main plate portion 18a and a sub plate portion 18b. The main plate portion 18a and the sub plate portion 18b are integrally formed by a single plate member, and the sub plate portion 18b formed to have the same length as the four sides of the main plate portion 18a is the main plate portion 18a. It is bent on one side and formed into an annular shape. That is, the sub-plate portion 18b are respectively songs folded onto one surface of the main plate portion 18a from Gerare four sides of the main plate portion 18a. Therefore, the sub-plate portion 18b in this embodiment is located at a position larger than the outer periphery of the cross-sectional shape of the antenna 1 orthogonal to the single axis X in the direction orthogonal to the single axis X from the main plate portion 18a within the range of the installation portion 5. The portion 4 extends to the lower surface 4b side.
[0030]
Although the present invention has been described above with reference to preferred embodiments, it is needless to say that the present invention is not limited to the above-described embodiments. For example, the main plate portions 11a and 18a are substantially square, but may be other polygons, and may be circular or elliptical.
[0031]
Furthermore, although the sub-plate portions 11b and 18b are respectively formed on the four peripheral edges of the main plate portions 11a and 18a in the above embodiment, the antenna is orthogonal to the single axis X in the direction orthogonal to the single axis X. the sub-plate portion 11b by cutting Oko Succoth main plate portion 11a, a 18a in position greater than 1 cross-sectional shape, may be formed 18b on any form of is a matter of course.
[0032]
【The invention's effect】
As is clear from the above description, in the present invention, since the sub-plate portion is not formed so high as to cover the rear side of the antenna, ground noise can be reduced, so that the sensitivity of the helical antenna is improved. Can do. Further, the ground plate grounds the radio wave received from the rear side of the antenna by the main plate portion having a flat plate shape, and also grounds the radio wave from the surroundings on the rear side of the antenna by the sub plate portion, thereby reducing the ground noise. be able to.
[0033]
Therefore, since the ratio of the front side and the rear side becomes large, the sensitivity of the antenna can be further improved.
[0034]
Further, in the present invention, when the antenna is operated near the radio set, it is possible to reduce the influence of unnecessary radiation from the set.
[Brief description of the drawings]
FIG. 1 is a front view showing a cross section of a part of an antenna device according to a first embodiment of the present invention.
FIG. 2 is a plan view of the ground plate shown in FIG.
FIG. 3 is a left side view of the ground plate shown in FIG.
4 is a front view of the ground plate shown in FIG. 1. FIG.
FIG. 5 is a perspective view showing a ground plate in an antenna device according to a second embodiment of the present invention.
6 is a development view of the ground plate shown in FIG. 5. FIG.
FIG. 7 is a front view showing a configuration of a conventional antenna device.
8 is a perspective view showing the ground plate shown in FIG. 7. FIG.
[Explanation of symbols]
1,21 Antenna 3,23 Case
4 cases
Upper surface of 4a case
Bottom surface of the 4b case part 5,25 Installation part
5a bottom surface 11, 18, 31 ground plate 11a, 18a main plate portion 11b, 18b sub plate portion
X uniaxial

Claims (2)

In an antenna device including a columnar antenna that is a helical antenna, a case that supports the antenna, and a conductive ground plate provided in the case ,
The case includes a case portion that supports the antenna in a uniaxial direction parallel to a single axis, and the upper surface that faces the upper surface so that the case is installed in a state where the antenna is erected from the upper surface of the case portion. An installation portion provided on the lower surface of the case portion,
The case portion and the installation portion have a cross-sectional shape larger than the cross-sectional shape of the antenna orthogonal to the one axis in a direction orthogonal to the one axis,
The ground plate has a cross-sectional shape larger than the cross-sectional shape of the antenna orthogonal to the one axis in a direction orthogonal to the one axis, and is provided on the bottom surface of the installation part facing the lower surface of the case part. A flat plate-shaped main plate portion extending from the main plate portion to the lower surface side of the case portion at a position larger than the outer periphery of the cross-sectional shape of the antenna orthogonal to the one axis and within the range of the installation portion An antenna device comprising: a sub-plate portion . 2. The antenna device according to claim 1 , wherein the main plate portion and the sub plate portion are integrally formed by one plate member, and the sub plate portion is bent from a peripheral end side of the main plate portion. The antenna device is formed by cutting or raising the main plate portion .

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