JPH09260927A - Antenna system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antenna system with which directivity can be variably controlled corresponding to mechanical displacement by variably controlling the directivity corresponding to an apex angle formed by an inverted V-shaped loop path with a reception frequency. SOLUTION: This antenna system 1 is provided with a loop path for which a conductor D to become a prescribed effective electric length corresponding to the reception frequency is folded into inverted V shape. The inverted V-shaped loop path is formed by successively folding the conductor D from an power feeding point F to nodes 1a-1e. In such a form, vertical angle α facing the power feeding point F, hypotenuse L1 forming the vertical angle α, short line L2 and conductor D diameter ϕ become parameters to decide antenna characteristics. In this case, when azimuth angles 0 deg., 90 deg., 180 deg. and 270 deg. in directional patterns are respectively defined as south, east, north and west, a main robe is generated in the east-west direction concerning the direction pattern for which the length of the oblique line L1 is 0.5λ and the apex angel is from 30 deg. to 60 deg.. On the contrary, in the directional pattern for which the vertical angle 90 deg., the main robe is changed into south-north direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna device suitable for use as, for example, an indoor antenna of a radio or a television receiver.

[0002]

2. Description of the Related Art Conventionally, rod antennas and loop antennas have been known as those arranged indoors to receive television broadcast waves and the like. Since the rod antenna has an expandable structure, it is easy to store, but
Since the antenna gain is low and the directivity is weak, the image quality may be deteriorated by a ghost in a weak electric field region. On the other hand, in the loop antenna, an antenna conductor having an effective electrical length of 1.0λ to 1.5λ is formed in a ring shape with respect to a predetermined intermediate wavelength λ in the broadcasting frequency band, and directivity is provided by a method such as impedance loading. This is intended to improve the antenna gain. Therefore, with the loop antenna, even in a place where the broadcast wave is weak or a place with a lot of reflection such as a building town, a clear image can be received by adjusting the maximum directivity direction to the direction of the broadcasting station.

[0003]

By the way, in the above-mentioned loop antenna, in order to avoid the influence of the interfering radio waves, it is necessary to rotate the antenna direction to change the pointing direction. In particular, in order to remove an interfering wave whose arrival direction changes with time due to scattering or the like, the antenna direction must be rotated and adjusted each time. Therefore, there is a demand for an antenna device that is a one-element antenna but that can variably control the directivity only by applying mechanical displacement. The present invention has been made in view of the above circumstances, and an object thereof is to provide an antenna device capable of variably controlling directivity in accordance with mechanical displacement.

[0004]

In order to achieve the above object, in the invention described in claim 1, a loop formed by bending a conductor D having a predetermined effective electrical length with respect to a reception frequency in an inverted V shape. It is characterized in that a directivity is variably controlled according to an apex angle α formed by the inverted V-shaped loop path.

According to a second aspect of the present invention, the apex angle α is arranged at a position facing the feeding point F and is variably adjusted according to a mechanical displacement. . Further, in the invention according to claim 3, the loop path is formed by a plurality of bendable nodes. Further, in the invention according to claim 4,
Conductor D having a predetermined effective electrical length with respect to the reception frequency,
The amount of displacement is calculated based on the inverted V-shaped bent loop path and the signal level of the received broadcast wave, and the apex angle α in the inverted V-shaped loop path is adjusted in accordance with the calculated amount of displacement to form the loop. And a control means for automatically controlling the directivity of the road.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an antenna device according to an embodiment of the present invention will be described with reference to the drawings. First,
FIG. 1 is a diagram showing a schematic configuration of an antenna device 1 according to the present invention. The antenna device 1 is an antenna including a loop path in which a conductor D having a predetermined effective electrical length with respect to a reception frequency is bent in an inverted V shape. As shown in FIG. 1, the inverted V-shaped loop path is formed by sequentially bending the conductor D from the feeding point F to the nodes 1a to 1e. In such a shape, the apex angle α facing the feeding point F and the hypotenuse L ₁ (throats 1b to 1c, 1c to 1d) forming the apex angle α are formed.
Interval), the short side L ₂ (between the nodes 1a to 1b and 1d to 1e) and the conductor D diameter φ are parameters that determine the antenna characteristics.

Here, a directional pattern of the antenna device 1 having the above structure is shown in FIG. FIG. 2 shows that the length of the hypotenuse L ₁ forming the apex angle α is 0.2λ to 0.
When set to 6λ (λ: wavelength), the apex angle α is 30 ° to 180
The directional patterns are shown in each case when the angle is changed to 0 °. As can be seen from this figure, for example, the hypotenuse L
_When the length of ₁ is 0.5λ and the apex angle α is 90 °, the direction of the main lobe is shifted by 90 °.

That is, the azimuth angle "0" in the pointing pattern.
When “°”, “90” °, “180” ° and “270 °” are “south”, “east”, “north” and “west” respectively, the hypotenuse L
_{In the} directional pattern in which the length of ₁ is 0.5λ and the apex angle α is 30 ° to 60 °, the main lobe occurs in the east-west direction. On the other hand, in the directional pattern in which the apex angle α exceeds 90 °, the main lobe changes in the north-south direction. In other words, if the apex angle α of the inverted V-shaped loop road is changed,
It can be said that the directivity can be variably controlled.

From the directional pattern characteristics shown in FIG. 2, it has been understood that the directivity can be changed according to the apex angle α, but a concrete example of the antenna device 1 is shown in FIGS. It becomes a structure. First, in the nodes 1a to 1e for bending the conductor D, as shown in FIG. 3, the conductors D made of corrosion-resistant aluminum or the like are pressure-bonded to each other by a spring SP made of a conductive metal, which can be connected. Cover with waterproof rubber rubber. Thereby, each node 1a-
1e is bendable and forms an inverted V-shaped loop path. The springs SP are used for the nodes 1a to 1e because they also serve to shorten the mechanical length of the conductor D portion while maintaining the effective electrical length of the entire loop path.

Next, with reference to FIG. 4, an example of a structure for varying the apex angle α according to the mechanical displacement will be described. In FIG. 4, 10 is a rail, and the node 1e is locked and fixed to one end thereof. Reference numeral 11 denotes a moving motor that rotatably supports the node 1a, and moves on the rail 10 in response to driving. According to such a structure, when the moving motor 11 moves to the right in the figure, the node 1e is fixed to the rail 10, so that the vertical angle α ₁ to the vertical angle α _{2 of the} inverted V-shaped loop road are increased.
Changes to

As described above, since the antenna device 1 according to the present invention can variably control the directivity according to the mechanical displacement, for example, in the case of removing an interfering wave whose arrival direction changes with time, the conventional method is used. Unlike the loop antenna, it is not necessary to rotate and adjust the loop opening direction, and the interference wave can be removed only by giving a mechanical displacement.

In the above embodiment, in order to apply the drive current to the moving motor 11, for example, the feeding point F
It suffices to supply it from the choke coil provided in the above through the conductor D. Further, instead of the moving motor 11, for example, the rail 10 and the moving motor 11 may be configured by linear induction motors. In that case, the moving motor 11 side serves as a non-magnetic rotor and the rail 10 side serves as a stator. further,
It is also possible to configure the rail 10 and the moving motor 11 with ultrasonic actuators.

In the above-described embodiment, the apex angle α is changed according to the mechanical displacement to variably control the directivity. However, if this is further developed, the received broadcast wave It is possible to automatically control the directivity by calculating the mechanical displacement amount based on the signal level and adjusting the apex angle α according to the calculated mechanical displacement amount.

[0014]

According to the present invention, the directivity of the conductor D having a predetermined effective electrical length with respect to the reception frequency is variably controlled according to the apex angle α of the loop path formed by bending the inverted V shape. So
The directivity can be variably controlled based on the mechanical displacement that adjusts the apex angle α.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic structure of an antenna device 1 according to the present invention.

FIG. 2 is a hypotenuse L ₁ and an apex angle α in the antenna device 1.
It is a figure for demonstrating each directivity pattern when using as a parameter.

3 is a diagram showing a structure of nodes 1a to 1e in the antenna device 1. FIG.

FIG. 4 is a diagram for explaining one structural example of adjusting the apex angle α according to mechanical displacement.

[Explanation of symbols]

1 ... Antenna device, 1a-1e ... Node, α ... Apex angle, D ... Conductor, F ... Feeding point

Claims (4)

[Claims] 1. A loop path in which a conductor D having a predetermined effective electrical length with respect to a reception frequency is bent in an inverted V shape,
An antenna device, wherein directivity is variably controlled according to an apex angle α formed by the inverted V-shaped loop path. 2. The antenna device according to claim 1, wherein the apex angle α is arranged at a position facing the feeding point F and is variably adjusted according to a mechanical displacement. 3. The antenna device according to claim 1, wherein the loop path is formed by a plurality of bendable nodes. 4. A displacement amount is calculated based on an inverted V-shaped looped path of a conductor D having a predetermined effective electrical length with respect to a reception frequency and a signal level of a received broadcast wave,
An antenna device comprising: a control means for automatically controlling the directivity of the loop path by adjusting the apex angle α in the inverted V-shaped loop path according to the calculated displacement amount.