US2558727A - Antenna - Google Patents

Description

Jllly 1951 I E.' J. BERNET I 2,553,727

I ANTENNA 4 mica July 1. 1942 I 4 2 Sheets-Sheet 2 gwumm- Patented July 3,- 1951 ANTENNA Edwin J. Bernet, Washington, D. '0. Application July 1', 1942, Serial No. 449,309

13 Claims.v .(Cl. 250-33.53)

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) bearing of an obstacle producing a reflection. It

is customary when attempting to improve the directivity of an antenna to use refl :ctors and other auxiliary apparatus, the combination of which heretofore has resulted in a bulky, wind-resistant array. This is extremely detrimental to those arrays that are mounted on a relatively high mast such as those used on board ships or other locations where there is a limited amount of space.

It is well known to those skilled in the art that a slight shift in frequency will produce a corresponding shift in wave length, which will often give rise to a considerable shift inthe line of focus of a beam radiated from an antenna unless special attention is paid to the method of feeding energy to the array. This, too, is extremely detrimental in cases where the operator is determining the bearing of an obstacle in accordance with the position of the antenna.

In many antenna arrays a voltage node will occur at the feed point, thus requiring the use of insulators at this point as a form of mechanical support for the radiators. These insulators are subject to a breaking stress, due to the relative movement of the radiators caused by wind, and also, due to flu gases and other extraneous bits of matter, may become sumciently corroded to conduct, thereby causing a mismatch in the feed impedance of the. radiators. These and other disadvantages are overcome by the present invention.

It is an object of this invention to construct an antenna array having a small amount of wind resistance with maximum beam directivity and structural rigidity.

It is another object of 'this invention'to provide a system of feeding energy to a uni-directional antenna array in which the line of focus of the radiated beam will remain unchanged for small variations in frequency.

-a uni-directional antenna array which is both compact and remarkably light in weight.

It is still another object of this invention to requires a minimum number of insulators in its construction.

It is still another object of this invention to provide an antenna array that will employ feed conductors of such size and spacing as to supplement the rigidity of the array.

It is still another object of this invention to provide an antenna array which will readily lend itself to the formation of larger arrays and also obviate the use of an intricate feed system.

It is still another object of this. invention to provide a uni-directional antenna array minimizing radiation losses.

It is still another object of this invention to provide an antenna array which may easily be rotated.

Other objects of this invention will become apparent upon a careful consideration of the following when taken together with the accompanying drawings, in which:

Fig. 1' is an elevational view of an antenna array embodying the principles of this invention;

Fig. 2 is a side view of Fig. 1;

Fig. 3 is an elevational view illustrating a modification of this invention, and

Fig. 4 is a side view of Fig. 3.

The antenna array unit of Figs. 1 and 2 con- I sists of six half-wave radiators I, 2, 3, and I, 2', 3' arranged so that three parallel sets of dipoles lying in the same plane will exist. The elements of the dipoles are interconnected by half-wave transposition lines 4, and are rigidly supported in a plane parallel to that of the antenna frame 5 by conducting members 6. Said members 6 are preferably brazed at one end to the voltage node point of their respective radiating elements,

and the opposite endis fixed in a similar manner to the antenna frame 5. In view of the fact that members 6 possess a certain amount of self-inductance and are also placed at voltage node points of the radiators, no insulators will be required at these points of connection. The reflectors comprise a series of parallel rods I immovably and conductively secured to the antenna frame 5 parallel to the dipoles. For purposesof clarifying the illustration in the drawings, those reflector rods I immediately behind the radiators are broken oil, it being understood that in practice these rods run the length of the antenna frame 5. As shown in Figs. 2 and 3 the antenna frame 5 is supported by a number of angular members 25 which form a supporting yoke from which the antenna may be suspended and rotated.

same diameter as feeders 8 to improve the inechanical rigidity of the array.

Generally there are two sources of back radiation, that radiation which leaks through between the reflectors I and that radiation which leaks around the end. The radiation that leaks through can be controlled by increasing the number of reflectors, while that radiation which leaks around the end can be controlled as a function of the angle between the plane of the antenna frame 5 and a line drawn from the end of said frame to the end of the radiators. Consequently the length of reflectors I will be determined in accordance with the respective lengths of members 6 and radiators I, I, 2, 2' and 3, 3'. It has been ascertained that optimum reflection can be obtained when the length of members I5 is approximately one-tenth wave length. It has also been ascertained that the diameter of the reflectors I is of little importance in controlling the amount of back radiation, consequently a rigid reflector rod of small diameter may be used. However, the

sum total of back radiation resulting from a system of reflectors of the class described is less than one percent.

The parallel positioning of reflectors I per dipole is determined in the following manner:

If, for example, considering the lower dipole I, I, eleven reflectors per dipole are used, a first reflector would be located at a point II on the antenna frame 5 equidistant from the adjacent dipoles I, I' and 2, 2'. A second reflector is located at point Ill displaced from first mentioned reflector by a distance equal to the vertical distance between adjacent dipoles. The interval between reflectors at points I0 and II contains nine reflectors located at the points of intersection of antenna frame 5 with a series of equal angularly displaced planes radiating from the longitudinal axis of dipole I, I'. It is therefore obvious that the spacing between reflectors farthest disposedfrom the dipole will be greater than the spacing between thosereflectors which are located nearest the dipole. This procedure is carried out for each dipole.

When greater power gain is required any number of units shown in Fig. 1 may be used as convenient building blocks. It must be understood,

The reference character 2i pertains to a metal cylinderof one quarter-wave length surrounding the outer coaxial conductor of the transmission lines I2, l3 and is sometimes referred to as a Bazooka. It is commonly used for transforming from coaxial conductors to balance two wire lines.

It is apparent. that the arrays of both Figs. 1 and 4 are energized at a point of electrical symmetry; consequently when a shift in wave-length occurs the elements on all sides of the point of symmetry will undergo the same electrical wave deviation. Thedeviation on one side of the symmetrical point will balance out the deviation on the other side of said point, thereby maintaining the array in a state of electrical equilibrium. That is, the radiated beam will have the same line of focus for any small variation in frequency.

It' is readily seen that these arrays may be inclined at any angle from 0-90 with the horizontal axis and rotated 360 about the vertical axis at any degree of inclination.

Although I have described and shown certain and specific embodiments of my invention, 1 am fully aware that many modifications thereof are possible. My invention is not to be restricted except insofar as is necessitated by the prior art and by the spirit of the appended claims.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

' I claim:

1. A uni-directional antenna array comprising an antenna frame, six half wave radiators so positioned that three paralleldipoles exist, each of however, that any odd number of dipoles may also be used, such as one, five and etc., without departing from the spirit of the invention. The array shown in Figs. 3 and 4 consists of six units. Units I A, B and C are co-linear and their elements lie in the same plane parallel to the plane of the antenna frame 5. Units A, B and C are also colinear and their elements lie in the same plane containing units A, B and C. Coaxial lines I2 and I3 branching from coaxial line I4 are tied to parallel feeder lines I5 and I5 at mid-points I1 and I1. Feeder lines I5 and I5 are two wavelengths long and have quarter wave matching sections 20 at points l1, l1, I8, I8 and I9, I9 one wave-length apart. Other end of the matching sections 20 is connected to the center dipole of their respective units A, B, C and A, B and C'.

said dipoles lying in the same plane offset from the plane of said frame, a conducting member rigidly supporting each of said radiators in said plane, each of said conducting members being immovably and conductively secured to said frame and to the voltage node point of its respective radiator, a plurality of sets of reflecting rods conductively secured to said antenna frame,

the rods of each of said sets being parallel to and symmetrically associated with their respective dipole, and lying along the lines of intersection of said antenna frame and a series of equal angularly displaced planes radiating from the axis of said dipole.

2. A uni-directional antenna array comprising an antenna frame, six half-wave radiators" so positioned that three parallel dipoles exist, each of said dipoles lying in the same plane ofiset from the plane of said frame, a conducting member rigidly supporting each of said radiators in said plane, a plurality of sets of reflecting rods conductively secured to said antenna frame, the rods of each of said sets being parallel to and symmetrically associated with their respective dipole, and lying along the lines of intersection of said antenna frame and a series of equal angularly displaced planes radiating from the axis of said dipole.

3. A uni-directional antenna array comprising an antenna frame, six half-wave radiators so positioned that three parallel dipoles exist, each of said dipoles lying in the same plane offset from of equal angularly. displaced planes radiating from the axis of said dipole.

4. A uni-directional antenna array comprising an antenna frame, a plurality of half-wave radiators so positioned that a plurality of parallel dipoles exist, each of said dipoles lying in the,

same plane offset from the plane of said frame,

a conducting member rigidly supporting each of said radiators in said plane, each of said conducting members secured to said frame and to the voltage node point of its respective radiator, a plurality of sets of reflecting rods conductively secured to said antenna frame, the rods of each of said sets being parallel to and symmetrically associated with their respective dipole, and lying along the lines of intersection of said antenna frame and a series of equal angularly displaced planes radiating from the axis of said dipole.

5. A uni-directional antenna array comprising an antenna frame, a plurality of half-wave radiators so positioned that a plurality of parallel dipoles exist, each of said dipoles lying in the same plane offset from the plane of said frame, a conducting member rigidly supporting each of said radiators in said plane, a plurality of sets of reflecting rods conductively secured to said antenna frame, the rods of each of said sets being parallel to and symmetrically associated with their respective dipole, and lying along the lines of intersection of said antenna frame and a series of equal angularly displaced planes radiating from the axis of said dipole.

6. A uni-directional antenna array comprising an antenna frame, a plurality of half-wave radiators so positioned that a plurality of parallel dipoles exist, each of said dipoles lying in the same plane offset from the plane of said frame, a plurality of sets of reflecting rods conductively secured to said antenna frame, the rods of each of said sets being parallel to and symetrically associated with their respective dipole, and lying along the lines of intersection of said antenna frame and a series of equal angularly displaced planes radiating from the axis of said dipole.

7. A uni-directional antenna array comprising an antenna frame, a radiator lying in a plane offset and parallel to the plane of said antenna frame, a member conductively and securely supporting said radiator in said plane, a plurality of parallel rod-shaped reflectors conductively secured to said antenna frame and symmetrically associated with said radiator, said rod shaped reflectors being located at the lines of intersection of said antenna frame and a series of eq al angularly displaced planes radiating from the axis of said radiator.

8. A uni-directional antenna array comprising an antenna frame, a radiator lying in a plane offset and parallel to the plane of said antenna frame, a plurality of parallel rod-shaped reflectors conductively secured to said antenna frame and symmetrically associated with said radiator, said rod shaped reflectors being located at the lines of intersection of said antenna frame and a series of equal angularly displaced planes radiating from the axis of said radiator.

9. A uni-directional antenna array comprising an antenna frame, a plurality of radiators parallel to and offset a predetermined distance from said antenna frame, means for supporting said radiators a predetermined distance from said frame,

a plurality of parallel rod-shaped reflecting means immovably secured to said antenna frame and symmetrically associated with each of said radiators, said reflectors lying along the lines of intersection of said antenna frame and a series of equal angularly disposed planes radiating from said radiators.

10. A uni-directional antenna, comprising a plurality of parallel dipoles and a series of rodlike reflectors symmetrically associated with each of said dipoles, said reflectors located on a surface offset a predetermined distance from said dipoles and parallel thereto, said reflectors associated with each of said dipoles and being so located on said surface that the spacing between adjacent reflectors increases progressively as their distance from a plane normal to said surface and containing the longitudinal axis of said dipole increases, said increase in spacing continuing for a distance equal to half the spacing between the adjacent dipoles.

11. A uni-directional antenna array compris ing an antenna frame, a plurality of radiating elements so positioned and supported as to lie in the same plane offset from the plane of said antenna frame, means for rigidly supporting said radiating elements in said plane, means for symmetrically energizing said antenna array, and a plurality of rod shaped reflecting means symmetrically arranged with respect to each of said radiators, said rod shaped reflecting means being so arranged that those most remote from the respective radiating elements are spaced farther apart than those immediately behind said radiating element.

12. A uni-directional antenna array comprising an antenna frame, a plurality of radiating elements so positioned and supported as to lie in the same plane offset from the plane of said antenna frame, means for symmetrically energizing said antenna array, and a plurality of rod shaped reflecting means symmetrically arranged with respect to each of said radiating elements, said rod shaped reflecting means being so arranged that those most remote from their respective radiating elements are spaced farther apart than those immediately behind said radiating element.

13. A uni-directional antenna array comprising an antenna frame, a plurality of radiating elements so positioned andsupported as to lie in the same plane offset from the plane of said antenna frame, and a plurality of rod shaped reflecting means symmetrically arranged with respect to each of said radiating elements, said rod shaped reflecting means being so arranged that those most remote from their respective radiating element are spaced farther apart than those immediately behind said radiating ele ments.

EDWIN J. BERNET.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,928,645 Dow Oct. 3, 1933 2,026,652 Ponte Jan. 7, 1936 2,061,508 Dallenbach Nov. 1'7, 1936 2,115,789 Schmid May 3, 1938 2,163,770 Von Radinger June 27, 1939

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