US2444320A - Antenna system - Google Patents

Description

June 29, 1948. o w o w JR 4 2,444,320

ANTENNA SYSTEM Filed Aug. 10, 1944 IN V EN TOR.

147 TOW/V5) Patented June 29, 1948 ANTENNA SYSTEM Oakley M. Woodward, Jr., Princeton, N. J., assignor to Radio Corporation of America, a corporation of Delaware Application August 10, 1944 Serial No. 548,817

This invention relates to radio antennas, and more particularly to antenna systems for pro viding horizontal uniform omnidirectional field patterns, with predetermined vertical directivity and uniform polarization.

The principal object of the present invention is to provide an improved type of antenna system which may be designed to provide a field pattern which is substantially uniform horizontally.

Another object is to provide a system of the described type which will radiate and respond to substantially only horizontally polarized energy.

A further object of the invention is to provide a system of the described type whichmay be designed to provide any desired degree of elevational directivity. I

A still further object is to provide an antenna system of relatively simple construction which may be designed readily to exhibit the required characteristics of uniform horizontal directivity and horizontal polarization. 1

These and other objects will become apparent to those skilled in the art upon consideration the accompanying drawing, of which a Figure 1 is a schematic plan view of a prior art antenna of the general type to which this invention relates,

Figure 2 is an elevation of the antenna of Figure 1,

Figure 3 is a schematic plan view of an antenna constructed in accordance with the present invention,

Referring to Figures 1 and 2, a typical prior art antenna for providing horizontal polarization comprises a plurality of stacked layers l, 2, 3 and 4, each comprising four horizontal dipoles 5, 6, l and 8 spaced uniformly around a cylindrical conductive support 9. Although the dipoles 5, 6,

l and 8 are represented by single lines, it is to be understood that each includes a pair'of 001-' linear conductors disposed end to end with the adjacent ends connected to the respective terminals of a transmission line, as described below with reference to Figure 6. It is sufiicient for the present to say that the radiators are all connected effectively in parallel to operatein phase,

so that the currents all flow in the same direction simultaneously, that is all clockwise or all counter-clockwise if viewed from the top, as indi- 11 Claims. (Cl. 250-3353) cated by the arrows in Figure 1. The layers I, 2, 3and 4 are spaced vertically along the support 9 at intervals of one-half wavelength. The elevationaldirectivity of the system is determined in accordance .with principles well known to those skilled in the art, by the number-of such layers. Each of the dipolesis spaced one-quarter wavelength radially from the surface of the support 9.

The field intensity in a-horizontal plane produced by the above-described antenna with a current I in each of the radiator elements is 26 of the following description, with reference to i where k is a constant, W0, W4, W8,

The corresponding horizontal directive pattern of the antenna of Figure 1 is illustrated by the curve designated E on the polar graph of Figure 5. The maximum field intensity is arbitrarily designated as F. Itis evident that the field is not uniform, but varies approximately 30 percent, from .707 F to 1 F.

The principle of the instant invention lies in superimposing upon the pattern of Figure 5 a similar pattern, displaced at an angleof 45 with respect thereto. Referring to Figures 3 and 4, an array constructed in accordance with the present invention comprises layers W, H, l2, l3 of radiators similar to the layers l, 2, 3 and 4 of Figure 2, with successive layers displaced horizontally through an angle of 45. Thus the radiators of the layer ID are parallel to the respective corresponding radiators of the layer l2, and at an angle of 45 to the respective corresponding radiators "of the layers ll and i3. As in the system of Figures 1 and 2, all of theradiators are operated in phase. With a current I flowing in each radiator, the field intensity in a horizontal plane produced bythe layers In and I2 is (a =:EW

It is apparent that Er is independent of the angle" and is therefore horizontally uniform. Any number of pairs of layers similar to thepairslllfi II and I2, I3 may be employed to provide any. desired degree of vertical directivity.

Referring to Figure 6, a preferred mechanical structure of the radiator elements is illustrated} The supporting conductor 9 is provided with a plurality of holes m which short' cylindrical sleeves M are secured, extending radiallyoutsleeves l4 are adaptedto receive with a press fit tubular members I5} Each'of the members I5 is provided. with'asho'ulder l6 *for' engagement with the outer end of the sleeve l4, "and carry at its outer end'a pai1""of "c0llinearconductors I] and I8; A'pair'of slots '19 areformed in the" member l5, extending radially inward toward the shoulder l6 forming a slot of a length hereinafter specified, The slots I!) lie in a plane at right'angles to themeinbe'rs I! and 18." A con ductor 2| issupported :coaxi'ally within the mem ber l5 by an insulat'or 22, and terminates at its:- inner end near 'the'surfacebf a conductor'23.'? A conductor 23" is supported coaxially Within the conductor The outer endof the conductor Zlf is bent at right angles and connected to the main-- ber l5 atits outeren-d at the pointz l.

Figure 6 shows 'only'a'portion'of a'singlelayer of radiator elements. The remainder of the elements of this layer, as well as those of the other layers, are identical in "construction'with those which are illustrated. l-loweven: the'dipolesof each layer are physically reversed in position: with respect to-tho se of the, adjacent layers, in order to provide inphase excitation of all ofthe dipoles-with one-half wave spacing: between ad jacent layers. a The instant invention is not lim; ited to a specific dipole structura'which is illus trated-merely to show one embodiment thereof.'

The. lower ends of the conductors 9 and 23 may be connected to 'a translation device such as [a 1 radio receiver or transmitter. The. inner con. ductor 23' is coupled to the conductors 2|. by virtue of the capacitance existing between the inner; ends of the conductors 2i and the surface of the} conductor 23. Assuming a voltage to be applied; between the conductors 9 and 23,,- current flows through this capacitance and "through the con-1 ductor 2| to the wall of themember adjacent.

the element 11, thence through the wallto'thi conductor 9. The flow of current through the; conductor 2| induces a voltage between the lowerf' end of the member l5 and the upper endat the. point of connection of the. radiator It, causing. current to flow in fromthe radiator 18 while; current is flowing out on the radiator '11, and vice versa. v I H The slots l 9 are somewhat less than one-quar ter wavelength long, The two portions of the ductive reactance between the slots I 9 and the capacitive reactance of the conductors H and I8.

Although the invention has been described with re'ferefice'to a specific type of radiator structure, it is "be'j understood that any type or radiator may. employed-"subject only to the limitation that pairs of layers of four radiators equally spaced around acircular conductive support are used, withsthradiators of one layer displaced horizontally 45 with respect to those of the other layers. Thisarrangement provides a directive pattern which isuniform throughout the horizontal plane, providing'the diameter of the circular support is substantially .6 and the radiators are Ward from the Surface/10f. the conductor Th spaced substantially A from the urface of-the support; The above dimensions may be changed throig hou-t a'limited :range without serious distortion otthe-desired circular pattern.

I claim as my invention:

1. An antenna system comprising a vertical conductive support andat least one pair of-horizontallayers of 'radiator elements, each layer comprising four" elements spaced' radially from said support and disposed at equal horizontal intervals-around said support; with the elements of 'onelayer "of each pair staggered horizontally by an'angle-ofv with-respect to those of the other layer of said pair means interconnecting saidsel'ements. so that the currents in all of said 3 5. elements-in allot said"layers are in time phase withreach other:

2;- An-antenna system comprising a cylindrical conductive Vertical support and a' plurality 'of horizontal layers of radiator-elements, each layer comprising four elements spacedradially from saidsupport: anddisposed at equal intervals around said support; with-the elements of each layer staggered; horizontally by an angle 'of 45 with 're'spectto those" of each adjacent layer layer of'each pair"displacedhorizontally 45 with 1 respect to the corresponding elements of the other layer ofsa-id pair means interconnecting said elementsso that'the currents in all of said elements in all of said layers are in time phase with each other;-

4. A11 antenna-"system comprising a cylindrical conductive verticalsupport and at least one pair of horizontal layers of radiator elements, each layer comprisingfour elements spaced radially from said supportand'disposedat 90 intervals aroundfsaid-"support, with the elements of. one

layer "of each pain-displaced horizontally 45 \m'th re's'pectto the corresponding elements of the other layereofwsaidpair' means interconnecting saidelehreiits so that she-currents in all of said conductor 15 separated by the slots l9 function:rm elementsrirtrall ffsaid layers are in time phase as a transmissiondine. shorted-atits lower end; providing an inductive reactancebetweenthe inner ends of the members i! and IB. The members l1 and H) are each somewhatless than oner-i,

with 'eachother:

.5.-r An antennasystem'comprising a hollow cylindricalvertical:conductor substantially .6 wavelengthzin' diaineterat the :frequency at which the quarter wavelength long, providing a capacitive systemrsis.stofnpirate, :atleast: one. zpairiof. horizontal layers, spaced vertically apart substantially one-half wavelength, of radiator elements, each layer comprising four elements disposed at 90 intervals horizontally around said support and substantially one-quarter wavelength distant radially from the surface of said support, with the elements of one layer of each pair displaced horizontally 45 with respect to the corresponding elements of the other layer of said pair, conductor means extending coaxially within said hollow conductor, and means for coupling the radiator elements of each of said layers to said conductors at substantially one-half wavelength intervals thereon, whereby all of said radiator elements are eifectively connected in parallel for operation in phase.

6. The invention as set forth in claim 5, wherein each of said radiator elements includes a horizontally disposed linear conductor.

7. The invention as set forth in claim 5, wherein each of said radiator elements comprises a horizontal dipole and the dipoles of each layer are orthogonally disposed with respect to each other.

8. The invention as set forth in claim 5, wherein each of said radiator elements comprises a dipole.

9. An antenna system comprising a hollow vertical conductor, at least one pair of horizontal layers, spaced vertically apart substantially onehalf wavelength, of radiator elements, each layer comprising four elements disposed at 90 intervals horizontally around said support with the elements of one layer of each pair displaced horizontally 45 with respect to the corresponding elements of the other layer of said pair, conductor means extending coaxially within said hollow conductor, and means for coupling the radiator elements of each of said layers cophasally to said conductors the connections of each layer being reversed with respect to those of the adjacent layers to provide cophasal operation of all of said radiator elements.

10. An antenna system comprising a cylindrical vertical conductor substantially .6 wavelength in diameter at the frequency at which the system is to operate, at least one pair of horizontal layers of radiator elements, each layer comprising four elements disposed at 90 intervals horizontally around said support and substantially one-quarter wavelength distant radially from the surface of said support, with the elements of one layer of each pair displaced horizontally with respect to the corresponding elements of the other layer of said pair,

11. An antenna system comprising a vertical conductor, at least one pair of horizontal layers of radiator elements spaced vertically apart, each layer comprising four elements spaced radially from said support and disposed at intervals horizontally around said support with the elements of one layer of each pair displaced horizontally 45 with respect to the corresponding elements of the other layer of said pair, and means interconnecting all of said radiator elements so that the currents in all of said elements in all of said layers are in time phase with each other.

OAKLEY M. WOODWARD, JR.

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

UNITED STATES PATENTS Number Name Date 2,086,976 Brown July 13, 1937 2,190,816 Wheeler Feb. 20, 1940 2,199,635 Koch May 7, 194.0 2,238,904 Lindenblad Apr. 22, 1941 2,298,449 Bailey Oct. 13, 1942 2,338,564 Aram Jan. 4, 1944

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