JPH05226933A - Decameter wave antenna having improved resistance against wind - Google Patents

Abstract

PURPOSE: To enhance the wind-resistance of a deca-meter, including at least a vertical dipole curtain among dipoles distributed into various level groups. CONSTITUTION: A substantially rectangular shape of known antenna dipole curtain is aborted, number of dipoles d2 , d3 , d5 -d8 , D1 -D8 of an upper group is selected smaller than number of dipoles d9 -d16 , D9 -D24 of a lower group to make the width of a top part of the curtain narrower. Reflectors Rb, Rh related to the curtain have a surface with a smaller width at upper parts than lower parts relatively. Thus, the performance characteristic in the case of radiation is slightly deteriorated by this modification, but the weight of the structure is much lighter and the resistance against wind is increased much higher. The disclosed antenna system is designed especially for a rotary antenna.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to decameter dipole array antennas, and more particularly to the problem of resistance of these antennas to wind. This problem frequently occurs not only in the rotating curtain antenna. This document is a solution that has investigated the problems associated with such antennas. A solution that fits a fixed antenna, such as an antenna in which an array or array of dipoles extends between a fixed mast and a normal vertical mast, is also described. In all these antennas, the dipoles of the same array are arranged substantially in the same plane, which can include a dipole array or dipole curtain without any distinction.

[0002]

BACKGROUND OF THE INVENTION Decameter shortwave dipole array antennas are antennas several tens of meters high and several tens of meters wide. Some of these can reach heights and widths of 100 meters or more. Known antennas have a rectangular vertical array formed by dipoles evenly distributed in overlapping rows and columns, the array of antenna dipoles being substantially rectangular or square in shape. The array has a reflector generally constructed of parallel wires, which is rectangular or square in shape and is substantially larger than the dimensions of the array, the reflector being arranged parallel to the array of dipoles. With such a large size of the deca-meter wave antenna, it is difficult to provide an antenna having a suitable rigidity, which is very expensive. If this rigidity is not suitable, as a result, the matching characteristics of the antenna characteristics are substantially deformed under strong wind. This deformation means that the radiation is blocked or stopped.

[0003]

The object of the present invention is to avoid these disadvantages, or at least reduce them.

[0004]

This object can be achieved by a different arrangement of the dipoles in the curtain than in the prior art, i.e. different shapes than rectangular or square.

According to the invention, the curtain is formed by radiation dipoles distributed in n groups on n (n is an integer equal to at least 2) different levels, arranged at the highest level. The number of dipoles in a group is at least one unit less than the number of dipoles in the lowest level, and between any two groups, the higher of the two groups is equal to two A decameter antenna is provided that includes a vertical curtain and a vertical reflector designed to operate within a given frequency range, having a number of dipoles equal to the lower one of the group.

[0006]

The invention will be understood more clearly and other features will become apparent from the following description and drawings.

Corresponding elements are designated by the same reference numbers.

1 and 2 are 82 meters high, including a support and two suitable antennas, a low frequency antenna operating in the 6-11 MHz radio band and a high frequency antenna operating in the 11-26 MHz radio band. , Shows a dual-rotating antenna for deca-meter shortwave with a width of 76 meters.

The support is a ring C placed on the roof of the room.
It has a hollow base made of block stacks forming a chamber L in which a mechanical assembly with a drive shaft for driving in a rotational direction and a transmitter are arranged. This ring is fixed to the lower end of a vertical mast M to which four horizontal girders P1 to P4 arranged on the same vertical plane are fixed. 40 beams (b1-b4 and B
1-B6, etc.) is secured to one first end of the girder. Rigid bars that build the stanchions (eg, T1 and T
2) or a large pillar (eg T3) is the girder P1
Mounted at the ends of ~ P4 and located substantially in the plane of these girders. Two large pillars (eg T3) allow the girder P2 to support the girder P1. Maintenance lines (eg H1 and H
2) is connected to the girder so that it is oblique to the mast. The mast M has three parts; a cylindrical vertical axis M1 having an annular cross section with a vertical grid girder mounted on it, and an assembly M3 having M2 mounted on it.
And an M3 formed by two bars welded at one of its ends to form an acute angle with the tip pointing upwards.
Have and.

The low frequency antenna is an HR 4/4 / 0.5 type antenna. That is, the antenna is such that the first row of dipoles has a height to the ground equal to 0.5 times the operating average wavelength of this antenna, four folded columns per row in the curtain and four folded half-wave dipoles per row. With a curtain H of horizontal dipoles with a reflector R. The curtain of the dipole of the low frequency antenna is therefore 40
16 free ends of the beams, eg beams b1 ...
It is constructed by 16 dipoles d1 to d16 fixed to b4. These dipoles are girders P1 to P
4 are arranged on the same vertical plane parallel to the vertical plane.
Similar to FIGS. 3 and 4, various dipoles are represented in FIG. 1 in front view by thick lines for their rigid parts and thin parallel lines for their parts constructed of wires. Dipole d
Between the vertical planes of 1 to d16 and the vertical plane of the girder, or more specifically in the plane of the front of the girders P1 to P4, construct a reflector Rb of a low frequency antenna formed by a sheet of horizontal wire. A third plane of parallelism is provided parallel to the first two planes. The horizontal wire of this reflector consists of the top of the mast M and the stanchions (eg T1 and T1).
(2, etc.) and is held by a edging cable C1 passing through the free ends of the bars that build it. Reflector R
The space between the horizontal wires of b is held by the horizontal wires, which are fixed at equal intervals by a vertical cable (for example, K1). The reflector Rb of the low-frequency antenna is not completely described in FIG. 1 so that the high-frequency antenna arranged behind it can be seen, but in FIG. 2 its outline is shown in the plane of the drawing. It is illustrated by a dotted line.

The high frequency antenna is a HR 4/6 / 0.75 type antenna, ie a reflector R having four folded half-wave dipoles per row and six per row in the curtain.
With a horizontal dipole curtain H. The first row of dipoles is at a height equal to 0.75 times the average operating wavelength of this antenna above the ground. The dipole curtain of the high frequency antenna is thus constituted by the dipoles D1 to D24 fixed to the 24 free ends (eg B1 to B6) of the 40 beams. These dipoles are arranged on the same vertical plane parallel to the vertical planes of the girders P1 to P4. With respect to the reflector Rh of the high-frequency antenna, it is formed by a vertical sheet of horizontal wire which is arranged in the rear plane of the girders P1 to P4 between the reflector Rb and the curtain of the dipole of the high-frequency antenna. The horizontal wire of the reflector Rh is mounted above the frame, which is distinguished by a edging cable (eg C2) supported at its lower end by two stanchions, such as T4, which are attached at one end to the lower girder P4. It is held via the girder P1. The space between the horizontal wires of the reflector Rh is held by the horizontal wires that are fixed at equal intervals by a vertical cable (for example, K2). Similar to the reflector Rb, the reflector Rh is not fully shown in FIG. 1 schematically so that the curtain of the high frequency antenna dipole behind it can be seen, but in FIG. Is illustrated by a dotted line showing its outline in the plane.

Due to the geometrical dimensions of the antennas of FIGS. 1 and 2 and the surfaces which make up the two dipole curtains and the two reflectors, the wind causes a lot of stress in the structure of the antenna, which stresses Must be propagated towards the ground. Therefore, the dynamic pressure of the wind increases as it gets higher. That is, strong stress is generated in the upper part of the antenna structure by the wind, and this action is further amplified because the lever arm is the longest in the upper part with respect to the ground. Furthermore, the upper part of the antenna greatly increases the vibration period of the structure. Therefore, the larger the cycle period, the greater the dynamic effect of wind. For this reason, it is necessary to deform the upper part of the antenna of FIGS.

FIGS. 3 and 4 show two types of modes obtained by deforming the upper portion of the antenna of FIGS. 1 and 2. These variants make it possible, in particular, to substantially reduce the cost of the antenna, since the mast M and the hollow base L no longer have to withstand the stresses as before and are not expensive to manufacture.

The antenna of FIG. 3 corresponds to the antennas of FIGS. 1 and 2.

The low frequency antenna dipoles d1 to d
4 has been omitted: -The length of the upper girder P1 has been reduced by about 2 / 3-The two tall pillars (eg T3 etc.) tilt on the mast and support the girder P1. Is replaced by two diagonal beams (eg J etc.)-The surface area of the low frequency reflector Rb can be significantly reduced by omitting its upper corner, the wires of this reflector being of the girders P1 and P2. At the ends, it can likewise be fixed by new stanchions (eg T5-T6 etc.)-The surface area of the high frequency reflector Rh can be reduced slightly by deforming the two upper corners of its fixing system: the length of the girder P1. The reduction causes the edging cable (eg, C2, etc.) to stretch upward.

When the antenna shown in FIG. 3 is compared with the antenna shown in FIGS. 1 and 2, the following results are obtained.

-Does not change the performance characteristics of the high frequency antenna at all-Reduces the gain of the low frequency antenna in the range of 0.5 dB-Elevates by 0.8 ° for each low frequency antenna; this is more due to the upper dipole It can be reduced by applying power-there is a weight loss of about 15% on the part of the antenna arranged on the base L.

In the antenna of FIG. 4 corresponding to the antennas of FIGS. 1 and 2, the dipole d of the low frequency antenna is used.
1, d4, d5 and d8 and the dipoles D1, D4, D5 and D8 of the high frequency antenna are omitted. By omitting this, the length of the girders P1 and P2 can be reduced by about 2/3, and the reflector R can be omitted by omitting the upper corners.
The surface area of b and Rh could be reduced. Here, it was possible to reduce substantially more than in the case of the antenna of FIG.

When the antenna shown in FIG. 4 is compared with the antenna shown in FIGS. 1 and 2, the following results are obtained.

The gain of the low frequency antenna can be reduced in the range of 1 to 1.5 dB depending on the frequency, and the elevation angle can be increased by 1 to 1.5 ° depending on the frequency. 0.8 to
It can be reduced in the range of 1 dB and its elevation angle can be increased by 1 °;
In addition, elevation level changes can be reduced by providing more power to higher level dipoles, ie, dipoles in the row that contain less dipoles than the lowest row in the array.

The invention is not limited to the described embodiments.
Accordingly, the present invention is generally applicable to fixed or rotating decametre wave antennas in which the dipole includes at least one of the vertical curtains of the dipole, between any two levels, the highest level dipole is lower than the lowest level. The number of dipoles in the lower, higher level group is distributed to the groups over various levels, which is approximately equal to the number of dipoles in the lower, if any, level group. Further, the number of dipoles may be odd in some groups and even in others. In this case, without being bound by this, the symmetry of the curtain is by offsetting the dipoles of the even group with respect to the odd group,
That is, it can be maintained by not maintaining a row-wise arrangement between dipoles of different levels.

The present invention has been described with respect to a folded half-wave dipole. It can also be applied to different types of dipoles, in particular, for example, when the dipole is a full wave dipole.

[Brief description of drawings]

FIG. 1 is a front view of a prior art antenna.

FIG. 2 is a side view of a prior art antenna.

FIG. 3 is a front view of the antenna of the present invention.

FIG. 4 is a front view of another form of antenna of the present invention.

[Explanation of symbols]

 b, B beam C ring C2 edging cable d, D dipole H curtain H1, H2 maintenance rope J diagonal beam K horizontal cable L room M mast P girder Rb, Rh reflector T1, T2 bar T3 three pillar T4 prop

Claims (6)

[Claims] 1. Decametric antenna, wherein the curtain is formed by radiating dipoles distributed over n groups on n (n is an integer equal to at least 2) different levels. The number of dipoles of the group placed at the level is at least one unit less than the number of dipoles of the group placed at the lowest level, and between any two groups, the higher of the two groups is Decametric wave including a vertical curtain and a vertical reflector designed to operate within a given frequency, having at least as many dipoles as the lower of the two groups. antenna. 2. The antenna of claim 1 wherein the reflector and curtain include a rotating vertical mast fixedly coupled to the mast. 3. A curtain associated with a mast, fixedly coupled to the mast, and designed to operate in a range of frequencies higher than a given range. An antenna as claimed in claim 2 including another vertical curtain formed by dipoles, arranged parallel to the reflector on the other side of the reflector. 4. The antenna according to claim 3, wherein the other curtain is a rectangular curtain having an overall size smaller than the size of the curtain designed to operate in a given range of wavelengths. 5. The dipole of the other curtain is m
(M is an integer equal to at least 2), and the number of dipoles of the group placed at the highest level is at least greater than the number of dipoles of the group placed at the lowest level. 4. The antenna of claim 3, wherein between any two groups less than one unit, the higher level group has a number of dipoles that is at most equal to the lower level group. 6. The power is distributed between the dipoles such that between the two groups having different numbers of dipoles, the one receiving the maximum power is the dipole of the smaller number of dipole groups. The antenna according to 1.