US2533236A - Antenna array - Google Patents

Description

Dec. 12, 1950 ANTENNA Filed Oct.

HIGH F/Ft'G, SOURCE R. A. FELSENHELD ARRAY Patented Dec. 12, 1950 ANTENNA ARRAY Robert Arthur Felsenheld, East Orange, N. J assignor to International Standard Electric Corporation, New York, N. 1., a corporation of Delaware Application October 3, 1947, Serial No. 777,606

6 Claims.

This invention relates to an arrangement of feeder lines for an antenna array and in particular to the arrangement of feeder lines to the individual antennas of a stacked double surface antenna array.

An antenna of the type comprising two elements such as discs, cones or similar elements with surfaces arranged to have a peripheral opening in the plane of radiation has been used. Such antennas are generally omni-directional with a polarization perpendicular to the surfaces at the opening. For convenience, these antennas will be herein referred to as double surface dipoles or dipole antennas. A coaxial line feeding such an antenna is arranged so that the outer conductor connects to the lower element and the inner conductor extends to connect with the upper element. When such antennas are stacked one above the other to form a vertical stacked array, each antenna is fed by separate coaxial transmission lines. Concentric line coaxially aligned with the common axis of the antennas have been proposed for feeding such arrays. With such a feed the line becomes very cumbersome if a considerable number of antennas are used. Moreover, it is difficult to supply each antenna with high frequency energy of the same power and phase. To avoid this, the antennas may be fed by a separate coaxial line of the same size. The feeder lines are then mounted on the outside of the array instead of axially inside the array. However, with the feeder lines on the outside of the array instead of axially inside the array, the symmetry of the radiation pattern is disturbed by reflection or re-radiation of the radiated energy from the lines. This eifect is of the cable distributes the effect of the cable on the radiation pattern at different azimuths.

For a better understanding of my invention reference is made to the following description taken in connection with the accompanying drawing and its scope will be pointed out in the appended the greater because of the vertical polarization.

across the opening between the two Surfaces of a each antenna only once and in a different sector of the azimuth from the other antennas. Each feeder line is terminated at a respective antenna.

The groupings of the cables reduces the effect of the cable due to reflection and the spiralling claims. The single figure of the drawing llliis trates an embodiment of my invention 10]. the feeding of a double surface dipole array wherein one surface comprises a disc and the other surface is a cone and is known as tne disc-cone type.

Referring to the drawing, the antenna array comprises nine antennas 01' the disc-cone type, I, 2, 3, l, 5, 6, t, 8 and 9, vertically stacked. The array is separated into an upper section it of antennas 5, ii, '1, 8, 9, and a lower section II of antennas l, 2,3 and 4 by the junction box hous ing it WlliCh may contain an impedance matching transformerand the extra lengths of cable.

Since the upper and lower sections are substantially the same, it will be necessary only to de-'- scribe the upper section to illustrate the embodiment of my invention.

In the upper section the antennas 5, 6, f, 8 and 9 are rigidly mounted on the flat insulator rings at I3, i i, l5, l6 and H. The insulator rings are rigidly fastened at spaced points to four vertical poles l3, i9, 20 and 2| that are rigidly mounted in the top plate 22 0f the junction box housing l2. A top plate 23 at the upper end of the section is rigidly fastened to the four poles to hold them in proper relationship to one another.

The antennas l, 2, 3, 4, E, i, 8 and 9 are con nected in parallel by the flexible coaxial feeder lines 24, 25, 26, 21, 28, 29, 30 and 3| to the transmission line 32 in the junction box housing 12. For cophasal energization of the antennas the feeder lines are all made equal in length, the extra lengths which are not extended for the nearer antennas, being contained within the junction box housing. The lengths of feeders may be chosen to provide other phasing of the energization. The feede line connecting the antenna 5 to the transmission line 32 is in the junction box housing l2 and is not shown. The transmission line 32 connects the feeder lines of the disc-cones to a high frequency energy source 33.

The feeder lines 28, 29, 30 and 3f are bound together by bands of string 34 and extend out of the junction box housing I2 through the hole 35 positioned between the poles 20 and 2| and in line with the periphery of the insulator it. They are pirally wound around the array and fastened to pole 20 at a point near the succeeding insulator it. The feed line 28 separated from the other 3 lines 29, 30, and 3| at this point and connects to antenna 6 as shown.

The remaining lines 29, 30 and 3| are continued to be spirally wound around the array and fastened to the succeeding pole [9 at a point near the insulator I5. The lines are held in position by notch 36 in insulator ring [4. Line 29 separates from lines 38 and 3| and connects to antenna 'i in the same manner as line 29 connects to antenna 6. The remaining lines 30 and 3! are spirally wound in a similar manner connectin to antenna 8 and 9 respectively.

In this embodiment of theinvention it is seen that the portion of the cable between the junction box housing [2 and the antenna .1 affects the radiation from between the disc and cone of antenna in an azimuth between poles 2G,.and2l. The portion of the cable between insulators H and I5 aifects the radiation from antenna 'l in an azimuth between poles l8 and IE! or substantially 90 from the disturbance, in the radiation pattern of antenna ,6. Each succeeding. antenna is affected in the succeeding. uadrant so, that the un fi t dradiation from .fOur .of the antenna will minimize thedistortion of the radiation of one of the antenna. Therebythe radiation pattern. over the entire azimuth will be afiected a minimum, amount.

With the antenna array separated into two sections the feeder lines can be grouped into two separate cables thereby reducing the size of the cable to further reduce the disturbance of the symmetry of the radiation pattern. Considering the lower section, the feeder lines 24, 25, 26 and 21 of the lower section of the array are spirally wound in a ,similarmanner and so that the radiation pattern of only. two of the antenna of the entire array are affected in the same quadrant. The antennas 2,1, 3 and ,4 are connected to the feeder ines 24, 25,26 and 21 respectively in the same manner that the antennas fth uppe s ti n ar connec edt the feeder lines. The cables 24, 25, Zfi and 21 extend past antenna 4. The feeder line 21 branches from the cable below the antenna 4 and connects to the antenna. Similarly, the other feeder lines extend past the respective antenna and connect tothe antenna from underneath. v While in the example illustrated the main feeder 32 is shown coming innormalto the antenna junction box housing it is clear thatfor other structures this may not be preferred. ,Should the antenna be mounted one. mast, for example, thefeeder 32.may be broughtupthe mast and positioned spirally aboutthe lower antenna portions in the same manner as the cables as shown. In this case it is preferable that the same pitch and path be followed bythemain cables and the feeder lines.

While I have indicated the pref erred embodiment of my invention, it is apparent thatmy invention is by no means limited to the exact form illustrated, but that many variations may be made in the particular structure used without departing from the scope of my invention as set. forth inthe appended claims.

What is claimed is:

1. In an array of double surface dipoles mounted vertically above one another and spaced a given distance from one another, a feeder system for said dipoles comprising a cable mounted at one end of at least a portion of said array, said cable having the same number of lines as antennas in said portion and being in the form of a spiral arranged about the outer peripheries of said antennas and cutting across the opening of each antenna once and in different sectors of the azimuth, each line of said cable being branchedfl'om said cable at a respective antenna and coupledthereto.

2. In an array of double surface dipoles mounted vertically above one another and spaced a givendistance from one another, a feeder system for said dipoles comprising a cable mounted at one end of at least a portion of said array, said cable having the same number of lines as antennas insaid portion andbeinginthe form of a spiral symmetrically advanced about .the outer peripheries of said antennas from said end and cutting across the openingsof the antennas in symmetrically arranged sectors .of the .azimuth, each line of said cable being branched from said cable at a respective antenna andcoupled thereto.

3. An array according to claim 1 wherein each line is a coaxial line.

4. An array according to claim 3 wherein the outer conductor of each line is coupled to the center of one of said surfaces and the inner conductor extends beyond saidone. surface and connects t the other surface.

5. An array, according to claim v1 wherein each of said doublesurface dipoles comprises a disc surface and acone surface, said discsurface beingpositioned above the apex of the cone surface and normal tothe axis of the cone surface.

6. In an array .Of. double surface dipoles mounted vertically aboveone another and spaceda givendistance frornone another, a feeding system for said dipoles comprisingtwo cables mounted in an intermediated position and being in the form of spirals arranged abouttheouter peripheries of separate portions of said array in oppositedirections from said centralposition, each cable having the same number of lines as antennas in eachrespective separate portion, each line of said cables being branched from said cables at a respective antenna andcoupled thereto.

ROBERT ARTHUR FELSENHELD.

REFERENCES GITED The following references are of record in the fileof this patent:

' UNITED STATES PATENTS Number Name Date 2,086,976 Brown July 13, 1937 2,350,916 Morrison June 6, 1944 2,368,663 Kandoian Feb. 6, 1943

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