JPH0770910B2 - Isotropic antenna - Google Patents

Description

The present invention relates to an isotropic antenna that operates with equal sensitivity to radio waves coming from any direction regardless of the plane of polarization of the radio waves.

(Prior Art) Generally, an antenna uses a vertical polarization plane antenna or a horizontal polarization plane antenna according to the polarization plane of a radio wave to be used. Recently, communication using circularly polarized waves and the like has been performed, and there are many antennas that operate regardless of the plane of polarization, but all of them are designed to have directivity due to the nature of communication.

(Problems to be Solved by the Invention) An antenna used for radio wave monitoring or the like needs to receive radio waves uniformly with no directivity not only in all directions, that is, in the horizontal direction, but also in a radio wave having an angle of refraction. Although it is desirable that it can be used in a wide frequency range, conventional antennas have no directivity for radio waves of both horizontal and vertical polarizations, and uniform reception is possible. There was a problem that it could not be done.

(Means for Solving Problems) The present invention provides a device that can be effectively used as an element of an antenna for radio wave monitoring and a wireless direction finder as described above.

As shown in FIG. 2, when the surface of one loop antenna (1) is arranged vertically, a so-called 8-character characteristic such as a directional characteristic (3) is obtained for a vertically polarized radio wave. However,
The loop antenna (2) is arranged orthogonal to the loop antenna (1) to form a so-called orthogonal loop antenna,
When the output of the loop antenna (2) is phase-shifted by 90 degrees and combined with the output of the loop antenna (1), E having an arrival direction α. The combined output voltage E of the orthogonal loop antenna for the sin wt radio wave (4) is E = E. Appears as sin (wt + α). As a result, as shown in FIG. 3, a directional characteristic (5) having a completely uniform directional characteristic is obtained. The loop antenna has a completely uniform directional characteristic with respect to vertically polarized radio waves having an angle of refraction, and its directional characteristic (6) is shown in FIG.

Therefore, the above orthogonal loop antenna is an isotropic antenna in which the directional characteristics are completely uniform with respect to both the horizontal directional characteristics and the vertical directional characteristics with respect to vertically polarized waves.
However, as it is, it does not function as an isotropic antenna for horizontally polarized radio waves, and the directional characteristics in the vertical plane are
As shown in the figure, it has an 8-shaped directional characteristic, and the horizontal direction is minimum and the vertical direction is maximum with respect to the incoming radio wave. Therefore, in order to make it effective for horizontal polarization, it can be easily understood that the orthogonal axis of the orthogonal loop antenna may be tilted 90 degrees to be horizontal. That is, the orthogonal axes of the two orthogonal loop antennas are arranged so that the orthogonal axes are in the vertical direction and the horizontal direction, and by extracting the outputs of both antennas, for radio waves coming from all directions regardless of the polarization plane of the radio waves, An isotropic antenna with completely uniform directional characteristics can be provided.

The present invention realizes this effectively by using only one 90-degree phase shifting means and one synthesizing means, while eliminating adverse effects such as phase difference due to path difference.

(Embodiment of the Invention) As is apparent from the above description, by disposing two orthogonal loop antennas with their orthogonal axes orthogonal to each other, an isotropic antenna irrelevant to the polarization of radio waves can be obtained.
However, if one of the two orthogonal loop antennas is arranged so as to overlap, one loop antenna can be shared.

FIG. 1 shows an embodiment of the present invention, in which one orthogonal loop antenna is formed by the loop antenna (1) and the loop antenna (2), and the output of the loop antenna (1) is a matching box (10). ) To the output combiner (13). The output of the loop antenna (2) is phase-shifted by 90 degrees by the matching phase shifter (11) and then added to the output combiner (13). The loop antenna (7) is provided such that its surface is orthogonal to the orthogonal axis (8) of the orthogonal loop antenna, and together with the loop antenna (2) forms an orthogonal loop antenna having an orthogonal axis (9). The output of the loop antenna (7) passes through the matching unit (12) and is added to the output combiner (13).

The output combiner (13) combines the outputs of the loop antenna (1), the loop antenna (2) and the loop antenna (7), and outputs two sets of orthogonal loop antennas, that is, the loop antenna (1) and the loop antenna ( The outputs of the orthogonal loop antenna of 2) and the orthogonal loop antenna of the loop antenna (7) and the loop antenna (2) are combined and the antenna output (14) is extracted.

Therefore, the antenna output (14) of the output combiner (13) is an isotropic antenna whose direction characteristics are completely uniform in any direction of arrival of radio waves by both vertical and horizontal polarized waves.

(Effects of the Invention) As is clear from the above description, according to the present invention, by adding one loop antenna to one orthogonal loop antenna, the directional characteristics are completely uniform with respect to vertical polarization and horizontal polarization. Such an isotropic antenna can be obtained. Since a loop antenna is used as the antenna element, an antenna that can obtain a highly sensitive antenna for a wide frequency band with a small volume is configured with only one 90-degree phase shifting means and one combining means. Therefore, the circuit configuration can be simplified, and since there is no path for branching the 90-degree phase shift signal into two branches, it is possible to obtain a combined output that is not adversely affected by the difference in the circuit constants of these two paths. It has features such as being able to.

(Modified Embodiment) FIG. 5 shows an embodiment in which the loop antenna has a circular shape. The loop antenna (1 ′) is the loop antenna (1) and the loop antenna (2 ′) is the loop. The antenna (2) and the loop antenna (7 ') correspond to the loop antenna (7), respectively. The loop antenna (2 ') forms an isotropic antenna for vertical polarization together with the loop antenna (1'), and the loop antenna (7 ')
It goes without saying that an isotropic antenna for horizontal polarization is also formed together with it.

In this case, since the entire shape can be made spherical, it is not only easy to manufacture, but also has a feature as an antenna with good wind speed resistance if it is constructed with a spherical antenna element attached. .

[Brief description of drawings]

2 is a horizontal plane directional characteristic diagram when the plane of the single loop antenna is vertically arranged, FIG. 3 is a horizontal plane directional characteristic diagram when the orthogonal axis of the orthogonal loop antenna according to the present invention is vertically arranged, and FIG. 4 is FIG. 3 is a side view of a vertical plane directional pattern in the arrangement of FIG. 3, FIG. 1 is a block diagram of an embodiment of the present invention,
FIG. 5 is an explanatory view when a circular loop antenna is used for the antenna element of the present invention. (1), (2), (7) and (1 '), (2'),
(7 ') is a loop antenna element, (3), (5) and (6) are directional characteristics, (4) is an incoming radio wave, (8) is an orthogonal loop antenna formed by the loop antennas (1) and (2). The orthogonal axis of (1), the orthogonal axis of the orthogonal loop antenna formed by the loop antennas (7) and (2), (1
0) and (12) are loop antenna matching units, (11) is a loop antenna (2) matching and 90-degree phase shifter, (13) is an output combiner, and (14) is an antenna output. .

Claims (1)

[Claims] 1. By arranging two loop antennas (1) and (2) orthogonally, and by arranging one loop antenna (7) in a plane orthogonal to the orthogonal axis, 3
An antenna means for arranging two loop antennas orthogonally to each other, and one phase shifting means for shifting only the output of one loop antenna (2) of the three loop antennas by 90 degrees (11) are provided, An isotropic antenna, comprising: a phase shift combining means for providing one combining means for combining the outputs of the remaining two loop antennas and the output of the phase shifting means.