JPS6126307A - Antenna system - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an antenna device that improves radio wave radiation efficiency and reduces wind pressure load, for example, in a grounded medium wave antenna.

[Prior art and its drawbacks]

In general, there are two main methods for installing conventional medium wave antennas: a base insulation method and a grounding method. In the former base insulation method, it is difficult to make the antenna a self-supporting structure, and the antenna is of a branch line type, which has the drawback of requiring a large antenna installation area and requiring a large amount of construction cost. On the other hand, in the latter grounded type, it is possible to make the antenna a self-supporting structure, so the installation area can be reduced;
On the other hand, since a steel tower is required for normal antenna installation, the construction cost may be lower if the antenna height is low, for example.
cannot obtain good radiation efficiency and is not economical.

[Purpose of the invention]

This invention was made in view of the problems mentioned above.
An object of the present invention is to provide an antenna device that can obtain good antenna radiation efficiency without requiring a large installation area, even when the antenna height is set low, for example.

[Key points of the invention]

That is, in the antenna device according to the present invention, a tapered pole that is thinner toward the top than the ground surface is erected perpendicularly to the ground surface, and the interval is widened from the top of the tapered ball toward the ground surface. A sub-conductor is suspended, and power is supplied between the tip of the sub-conductor and the ground plane, and the sub-conductor is made to have a thickness equivalent to that of the tapered ball, so that the characteristic impedance at each point of the antenna is equal. It was made so that it would become so.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

Figure 1 shows its configuration. First, the tapered ball 1
1 is perpendicular to the ground 12 and erected firmly. Here, the height above the ground (antenna height) is assumed to be j. Next, from the top JJa of the tapered ball 11, two conductors 13h
, 13b is suspended, and its tip is pulled and stretched from the ground 12 via an insulator 15.

Then, a transmitter 1 is placed on the side of the sub-conductor 14 sandwiching the insulator 15.
Connect 6 and supply power.

Here, in order to maintain strength against wind, the tapered ball 1.1 has an equivalent radius ρ that is thicker on the ground 12 side and thinner on the top 11a side. In addition, the equivalent radius ρ of the sub-conductor 140,
(described later) is also thicker on the ground 12 side and thinner on the top 11a side. Additionally, the distance between the tapered ball 11 and the sub-conductor 14 is widened on the ground 12 side and narrowed on the top 11th.

FIG. 2 shows the antenna device AA' in FIG. 1 above.
A cross section is shown.

Here, the coefficient a is determined as follows.

Next, let the radiation resistance of the antenna (antenna) be Rr(2), the equivalent grounding resistance at the operating frequency on the Taber ball 11 side be R8, and the equivalent grounding resistance on the sub conductor 14 side be R1(to).
shall be. Here, R1-n.

Considering this, the radiation efficiency of the antenna is as follows.

Figure 3 shows a characteristic curve when the horizontal axis is the ratio of the radiation resistance Rr and the grounding resistance R8, and the vertical axis is the radiation efficiency l(to). means an insulated antenna.

Here, the radiation efficiency l of the characteristic curve a-1 is maximum. Considering this using equation (1) above, ρ1−ρ,
It can be seen that this is the case. However, this condition assumes that a radiation current that contributes to radiation is flowing through the antenna. In addition, in the sub-conductor 14, the top 11 is lower than the ground 12.
In the radiation current flowing through a, the electromagnetic field created by the current flowing through the two conductors 1:9&, 13b of the sub-conductor 14 and one non-conductor 13a or 13 with the same length and radius ρ.
The electromagnetic field created by the current flowing through b coincides with the electromagnetic field except in the vicinity of the antenna. This radius ρ is called the equivalent diameter of the sub-conductor 14.

Here, the diameter of each conductor 13a, 13b is 2d,
If the interval is S, then the two conductors 13 &.

If the radii of isb are equal, the above equivalent radius ρ!
is □-f RO] "Equation (3) is obtained. That is, if the equivalent radius ρ2 of the sub-conductor 140 and the radius ρ of the tapered ball 11 are made equal as considered in the above equation (1), The characteristic curve in Figure 3 above is 11
-1, and the radiation efficiency η of the antenna becomes maximum. In this way, the equivalent radius of the tapered ball 11 is ρ! , sub conductor 1
40 When the equivalent radius is R2 and the mutual spacing is D, the characteristic impedance formed by these two cylinders zo
At ρ1-ρ, where the radiation efficiency l is maximum, ZO-120(Jn D-1nlJ@) Equation (4
). Here, in order to make the characteristic impedance Zo' constant at each height of the antenna, the taper ball 11
As the thickness R1 changes, the spacing must also change. In other words, the top of Teba Ball 1 JJ&
When is made thinner in order to reduce the wind pressure, the distance between the tapered ball 1 and the sub-conductor 14 inevitably becomes narrower as it approaches the top 11a according to the above equation (4).

Next, in the case of antenna height j, ρ1−ρ, , D
m4ρ1% Zo-166(]), ]ρ, lm-0.
0151X and the grounding resistance R15R1 is set to /(rammeter), the input impedance characteristics from the transmitter 16 side are shown in FIG. 4 (4) and ω).

Here, FIG. 4(4) shows the resistance component R1n, and FIG. 4(B) shows the actance component X1n. The horizontal axis is 2π
j/λ, and the point 1.507 (rid) corresponds to a quarter wavelength. In this case, to specifically express the antenna dimensions, if the characteristic impedance is Z0-166(2),
On the 12 surfaces of the earth, ρ, -ρ1-0.15 (→, D m
o, 6 (→, also at the top ρ1−ρ, −0.
05(→, D-0,2(→).Of course, the above earth 12
An intermediate value is taken between the surface and the top 11m. on the other hand,
On the sub-conductor 14 side, the conductor radius is d-0,005 (→, the conductor interval is S-0,5← from the above formula (3))
becomes.

The conducting wires 13* and 13b of the sub-conductor 14 are arranged in a straight line, triangular, quadrangular, polygonal, etc., with an equivalent radius ρ,
be large and placed so that the wind pressure load is small. As a result, the load on the tapered ball 11 can be kept small.

In the above embodiment, by installing two or more sub-conductors 14 for each of the 111 tapered balls, it is possible to create a frequency-sharing antenna. Further, by supporting the tapered ball 11 using a high-frequency insulated branch wire, the wind pressure strength can be further increased. In this case, electrical loading can be added by utilizing the upper part of the branch line with high frequency.

(Effects of the Invention) As described above, according to the present invention, an antenna with good radiation efficiency can be installed with a structure that has a small wind pressure load, so it does not require a large installation area and has good cost performance (performance-to-price ratio). It is possible to provide an excellent and economical antenna device.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing an antenna device IT according to an embodiment of the present invention, FIG. 2 is a diagram showing an AA' cross section of the antenna device in FIG. 1, and FIG. 3 is a diagram showing an antenna radiation efficiency curved edge. Figures 4(B) and 4(B) are diagrams showing the input impedance characteristics from the antenna feeder separately for resistance and reactance. 1 No. Taper ball, lla"-top, 12. Fist ground, 14. Subconductor, 16. Transmitter. Applicant's representative Patent attorney Takehiko Suzue Figure 1 Figure 3 r

Claims (1)

[Claims] A taper pole is erected perpendicularly to the ground plane and its thickness becomes thinner toward the top than the ground plane, and the tapered pole is suspended from the top of the pole with a widening interval in the direction of the ground plane and touches the tip. An antenna device comprising: a sub-conductor having a feeding point between it and the ground, the sub-conductor having a thickness equivalent to that of the taper pole.