US2480154A - Antenna - Google Patents

Description

Aug.. 3g@ w49. R. w. MASTERS ANTENNA i Filed Jan. 27, 1945 INTOR.

@ma f" iw@ Patented Aug. 30, 1949 ANTENNA Robert W. Masters, Erlton, N. J., assignor to Radio Corporation of America., a corporation of Delaware Application January 27, 1945, Serial No. 574,899

(Cl. Z50-33) 30 Claims. l

This invention relates to radio antennas, and more particularly to improvements in antennas of the type employing sheet radiators, such as are described in my copending U. S. Patent Application Ser. No. 574,898, led on the same date as this application and entitled Antenna The principal object of the present invention isr to provide an improved antenna of the sheet radiator type in which the sheets are so shaped as to provide greater vertical directivity than is obtained with the rectangular sheet radiators described in the above-mentioned application, while' retaining the advantages of broad-band characteristics and simplicity of structure.

The invention will be described with reference to the accompanying drawing, of which:

Figure 1 is an isometric view of a single layer turnstile type antenna structure embodying the present invention,

Figure 2 is an elevational View of a multiplelayer structure of the type shown in Figure 1,

Figure 3 is a schematic view of a radiator element similar to those in the structures of Figures 1 and 2, but of modified form,

Figure 4 is a perspective view of a radiator element of the type illustrated in Figure 3, wherein the sheet comprises a plurality of parallel conductive rods, and

Figure 5 is an elevation of a dipole structure according to the invention, wherein the sheet elements are comprised of wire networks.

Referring to Figure l, four flat plates or sheets I, 3, 5 and 'l are disposed radially at 90 intervals around a tubular conductive mast 9. One edge of each sheet lies parallel to and closely adjacent the mast Si. This edge is in each case connected at its top and bottom to the mast 9, at the points II and I3 respectively. Each sheet is approximately five-eighths wavelength long, at the mean frequency at which the system is to operate, and has a maximum width of substantially one-quarter wavelength.

The side of each sheet away from the mast 9 is provided with a broad V-shaped notch or cut-out portion extending in width along the entire length of the sheet, and having a depth at the center of the sheet of approximately one-eighth wavelength. In other words, the sheet varies in Width from one-eighth wavelength at its center to onequarter wavelength at its ends.

Four wires or lines I5, I1, I9 and 2l extend up` within the mast 9 as shown, or they may lie outside the mast. The lines I5, I'I, I9 and 2l are connected to the sheets I, 3, 5 and 'I respectively at the midpoints 22, 23, 25 and 21 of their edges adjacent the mast. The mast 9 is preferably grounded. 'Ihe lines are insulated from the mast, and may be surrounded with individual grounded coaxial sheaths. In this case, the mast 9 need not be of conductive material, but may be made of wood, for example.

In the operation of the system of Figure 1, the sheets I and 5 are energized as the elements of dipole, i. e. while va current I ows up the line I5, an equal current flows down the line I9, and vice versa. energized as the elements of another dipole, through the lines I1 and 2I. The currents in the lines I1 and ZI are in quadrature phase with respect to those in the lines I5 and I9, to provide a rotating iield which is substantially uniform in a horizontal plane about the antenna, as in the conventional turnstile. The lines I5, I l, I9 and '2| may be connected together and to a transmitter or receiver in any known way to provide the required current phase relationships. One suitable connection is described in U, S. Patent 2,086,976, issued July 13, 1937, to G. H. Brown.

Il'he current distribution in the sheet elements of the antenna of Figure 1 is such as to provide a vertical directivity approximating two layers of a turnstile antenna of conventional design such as that shown in the above-mentioned patent. The directivity is substantially twice that of a similar structure employing rectangular sheets, as described in my copending application Ser. No. 573,898. This improvement results from the shape of the sheets, which enforces the current to flow so that current maxima appear near the upper and lower edges of each sheet. Since the two maxima are separated vertically by approximately one-half Wavelength, radiation in the vertical direction from the upper half of the sheet is cancelled by vertical radiation from the lower half.

Although the exact manner in which the current flows is not known at present, it has been found experimentally that the structure of Figure 1 has a relatively broad resonance characteristic, permitting efficient operation over a wide frequency band. It is believed that the operation is somewhat as follows:

Each of the sheets, for example the sheet I, cooperates with the opposite sheet 5 to act as a parallel conductor transmission line section onehalf wavelength long, shorter at its ends II and I3 and fed at its center 22. This results in a standing wave, with maximum voltage at the point 22 and zero voltages at the points II and I3. Each horizontal element of the sheet I con- Similarly, the sheets .3 and 'I are stitutes a radiator connected to the parallel line, with current flowing in it in a direction radial to the mast 9. The nelds produced by these elements add together to produce a resultant eld approximating that which would be provided by a pair of radiators of conventional form, spaced apart vertically one-half wavelength. However, the overall impedanceA remains relatively conur stant with variation in frequency, probably be cause the voltage distribution along the parallel line varies, changing the relative currents in the various horizontal elements of the sheet.

Ihe vertical directivity may be increased, as in the convention-a1 turnstile antenna, by providing a series of layers of elements spaced vertically along the mast 9. Figure l corresponds in function to two radi'- ators, the layers should be spaced one wavelength apart vertically, as illustrated in Figure 2.

The upper and lower edges and the cut-out portion of the sheet radiators may be rounded, rather than rectilinear as shown in Figure 1. Referring to Figure 3, a single sheet radiator element is shown, supported on a conductive body |09 by connections l and l I3 at the upper and lower ends respectively of the sheet I0|. A transmission line is connected to the midpoint |22 of the edge of the sheet |0| adjacent the body |00. The width of the sheet |0| varies smoothly from a minimum of approximately oneeighth wavelength at its center portion to a maximum of one-quarter wavelength near its upper and lower ends, the shapeof said sheet may be likened to that of the cross-section of an hourglass.

The sheet radiators of my invention .may be made of assembled structures, such as, screens Vor sheets of parallel c-onductors consisting of Wires or rods. The term sheet as used herein and in the appended claims is intended to .include such structures. Referring to Figure 4, a sheet radiator 'of the same general hourglassv outline of that of Figure 3 is made up of a .plurality of parallel rods 203, supported radially of a .mast

209 on a conductive bar 205 lying parallel to and i:

closely adjacent the mast 209 and connected thereto at .its upper and lower ends 2-|| and 2|3. The operation of the structure is similar to tha-t of the above-described embodiments of the invention; However, the wind resistance is considerably less, an limportant consideration for out door structures.

Figure 5 illustrates another embodiment of the invention, including two sheet-like structures and 305 connected to lines 3|5 and 3H for use as a dipole. Each structure comprises al network of wires 303, supported between upper and lower cross arms 300 and 301 secured to a mast 309. Bars 3| extend close to and parallel to the mast 309 between the upper and lower cross arms, and are 'connected 'at their centers 322 vand 325 to the lines 3|5 and 3H, The antenna of Figure 45 is particularly suited for directive lreception of .high frequency signals such as are used for television, although it may be used advantageously `for transmission, or as an element of -a turnstile array. Although it has been stated throughout the above description that the sheet elements .are fed at their midpeints, they may be energized at any other point alongl the edge adjacent lthe mast if a lower input impedance is desired. The maximum impedance appears at the .mid-

point. v

The invention has been described as an im proved antenna including radiators in the form Since each of the sheets of of flat sheets, with one edge of each sheet grounded at its ends and fed at or near the center, and its other edge formed so that the sheet varies in width from a minimum at its center to a maximum at its ends. This arrangement forces currents to flow in the sheets in such manner as to provide considerable vertical directivity and broad resonance characteristics.

I claim as my invention:

l. A radio antenna including a support and at least one radiator element comprising a at conductive member of generally oblong outline, with one substantially rectilinear edge lengthwise thereof positioned adjacent and parallel to said support, and grounded at its ends, the width of said member midway of said edge being approximately one-fifth of the length of said edge, said member being of a maximum Width near the ends of said edge of approximately two-fifths of the length of said edge, and transmission .line means connected to said member at a point on said edge.

2. A radio antenna, including a grounded support and at least one radiator element comprising a fiat conductive member of generally oblong outline, with one substantially rectilinear edge substantially ilve-eighths wavelength long lengthwise thereof positioned adjacent and parallel to said support, and connected to said support at its ends, the width of said member midway of said edge being approximately oneith of the .length of said edge, said member be? ing of a maximum width near the ends of said edge of approximately two-fifths of the length oi said edge, and transmission line means connected to said member at the midpoint of said edge.

3. -A radiator element for radio antennas comprising a flat sheet of conductive material in .the form of a rectangle provided with a triangular l cut-out portion, with the apex of said triangle lying substantially at the center of said rectangle and the base of said tri-angle substantially coincident with one of the lengthwise edges of said rectangle and means for c-oupling radio frequency transducer .means to the other lengthwise edge of said rectangle.

4. A radiator element for radio antennas com-- prising a flat conductive member of generally oblong outline, having one substantially .recti.

linear edge extending lengthwise thereof, said member varying in width from a minimum of approximately one-eighth wavelength at its center to va lmaximum of approximately onequarter wavelength near each of its ends and means for coupling radio frequency transducer means to saidA rectilinear edge at substantially its midpoint.

-5. A radiator element for radio antennas comprising a at conductive member of generally oblong outline, having one substantially rectilinear edge extending lengthwise thereof, said member varying in width from a minimum at its center to a maximum near each of its ends and means for coupling radio 'frequency transducer means to f said rectilinear edge.

6. A radiator element for radio antennas comprising Ya ilat grid of conductive rods, said grid having a general-ly oblong outline, with one substantially rectilinear lengthwise edge and one curved .lengthwise edge, said second edge being of such shape that grid is of minimum width at its center and of maximum width near its ends and means for coupling radio frequency transducer means to said rectilinear edge.

7. A radiator element for radio antennas comprising a fiat sheet of conductive material of generally oblong outline, having one substantially rectilinear lengthwise edge and one curved lengthwise edge, said second edge being of such shape that sheet is of minimum width at its center and of maximum width near its ends and means for coupling radio frequency transducer means to said rectilinear edge at substantially its midpoint.

8. A radio antenna including a supporting member and at least one radiator element comprising a at sheet of conductive material'of generally oblong outline substantially one-quarter wavelength wide at its ends and substantially iiveeighths wavelength long, and substantially'oneeighth wavelength wide midway of its ends, said sheet having one substantially rectilinearv edge lengthwise thereof positioned parallel-to said support and grounded at its ends, and means for feeding said radiator element at a point on said edge.

9. A radio antenna including -a supporting member and at least one radiator element comprising a flat screen of conductive material of generally oblong outline substantially one-quarter wavelength wide at its ends and substantially five-eights wavelength long, and substantially one-eighth wavelength wide midway of its ends,

.said screen having one substantially rectilinear edge lengthwise thereof positioned parallel to said support and grounded at its ends, and means for feeding said radiator element at approximately the midpoint of said edge.

10. A radio antenna including a supporting member and at least one radiator element comprising a flat grid of conductive rods, said grid being of generally oblong outline substantially one-quarter wavelength wide at its ends and substantially ve-eighths wavelength long, and substantially one-eighth wavelength wide midway of its ends, said grid having one substantially rectilinear edge lengthwise thereof positioned parallel to said support and grounded at its ends, and means for feeding said r-adiator element at a point on said edge. V

ll, A radio antenna including a support and a number of radiating wing members, said wing members having a generally oblong outline with a substantially rectilinear edge positioned adjacent to and parallel to said support, said Wings being grounded at each end of said edge and transmission line means connected to said wings at a point on said edge intermediate said ends, said wings being substantially Wider near their ends than at the intermediate points.

12. A radio antenna including a number of radiating wing members radially arranged about a conductive supporting member, said wing members having a generally oblong outline with a substantially rectilinear edge positioned adjacent to and parallel to said support, said wing members being grounded at each end of said edge to said support and transmission line means connected to said wing at a point on said edge intermediate said ends, said wings being substantially wider near their ends than at intermediate points.

13. A radio antenna including a number of radiating wing members radially arranged about a conductive supporting member, said wing members having a generally oblong outline with a substantially rectilinear edge positioned adjacent to and parallel to said support, said wing members being grounded at each end of said edge to said support and transmission line means connected to said wings at a point on said edge intermediate said ends, said wings being substantially Wider near their ends than at intermediate points, said wing members being substantially one quarz ter wavelength wide at their ends and substantially ve eighths of a wavelength long, the width of said Wings being substantially one eighth wavelength midway of their ends.

14. A radiator element for radio antennas comprising a iiat sheet of conductive material of generally oblong outline having one rectilinear lengthwise edge rive-eighths of a wavelength long and one curved lengthwise edge, said second edge being of such shape that said sheet is one-eighth Wavelength in width at its center and one quarter Wavelength in width at its ends and means for coupling radio frequency transducer means to said rectilinear lengthwise edge.

15. A radio antenna including a supporting member and at least one radiator element including a flat sheet of conductive material of generally oblong outlineone quarter wavelength wide at its ends and tive-eighties of a wavelength long, said sheet being one-eighth wide midway of its ends, said sheet having one rectilinear edge lengthwise thereof positioned parallel to said supporting member and grounded at its ends and means for feeding said radiator element at a point on said rectilinear edge.

16. A radio antenna including a supporting member and at least one radiator element inw cluding a flat screen of conductive material of generally oblong outline one quarter wavelength wide at its ends and ve-eighths of a wavelength long, said screen being one-eighth wavelength wide midway of its ends, said screen having one rectilinear edge lengthwise thereof positioned parallel to said support and grounded at its ends and means for feeding said radiator element at the midpoint of said edge.

17. A radio antenna including a number of radiating wing members radially arranged about a conductive supporting member, said wing members having a generally oblong outline with one rectilinear edge positioned adjacent to and parela lel to said support, said wing members being grounded at each end of said edge to said support and a transmission line connected to said wing members at points on their rectilinear edges intermediate said ends, said wing members being wider near their ends than at intermediate points.

18. An antenna system comprising, as a radiating or receiving element a substantially plane member of conductive material and of a generally quadrangular shape, said member having one lengthwise substantially straight edge and bein grounded for radio frequency potential at the ends of said edge, said length being substantially equal to iive-eighths of a wavelength at the operating frequency, the width of said member mid- Way of said edge being substantially equal to one-fifth of the length of said edge, the maximum width of said member being near the ends of said edge and being approximately two-fifths of the length of said edge, a support for said monrber, and transmission line means connected. to said member at a point on said edge.

19. An antenna system comprising a plurality of radiating or receiving elements, each said clement including a substantially plane conductive member of generally quadrangular shape a quar ter wavelength wide by ve-eighths wavelengths long at the operating frequency and having a constricted width at the center of said member of an eighth wavelength disposed in a radial plane about a common axis and being substanessaim at the operating frequency at'those points on,the `said linear y edges ofv any two members which :points lie in the same plane normal to saidaxis v being substantially equal in amplitude and Yhaving an angular time phase diierence substantially equal to the angle between the axial planes :in which said two members are disposed. a sup-5 port for said elem-entaiand a transducer connected to said members.

20.- An antenna `system comprising,` as radiating or receiving elements, a pair of substantially plane members of conductive material each of a generally rectangular shape; each. said sheethav- Ning one lengthwise substantially straight edge and being grounded for radio frequency potentialat the ends of said edge, amaximum width subsstantially equal to a quarter wavelength-and a.

f minimum` width substantially an .eighth wavelength at the operating frequency, a length substantially equal tonve-eiglitns of a wavelength at the operating frequency, said membersbeing '1 disposed with said lengthwise edges closely adiacent and parallel to each other and in al common plane, a support for said members, and a transducer connected to said members.

2l. An antenna 'system including a pair of radiating members arranged in a plane, each of said radiating members comprising a relatively long conductor and a pluralityr of relatively shortconductors arranged in said plane normal to `,said lang conductors and having lengths varying from a minimum at the central part of said long conductor to a maximum near the ends of said.long conductor, the ends of thelong conductors of said radiating members being connected together, and means to couple a transmission vline fto the long conductors of said-radiating members at r points intermediate the ends thereof.

, 22. An antenna system includingnat..leaste-a pair of radiating members, said radiating members being constituted by` a pair of parallel conductors arranged to define a plane, a, pair of further parallel conductors. bridged across l the first said parallel `conductors substantiallyat-the center thereof, a plurality of secondary conductors equidistantly spaced in said plane normal .to said further conductors and' having lengths-varying 4from a minimum at the central partof `said further conductors t a maximum near the ends of said further conductorsl and tertiary conductors connecting the ends of said seconda-ry I'conlductors remote from said further conductors to 60 of said further conductors being connectedvvto.

conductors of each pair of collinearly arranged conductors at the adjacent ends thereof, a plu- -rality of secondary conductors. arranged-in said plane normal to said further conductors andihavvlng -lengths varying, from a.. minimum. ata-.the-

28 neutral partant' saidzfurther, .conductors to amaxle'imnmmear. theJ endsnof said :further nconductors iranditertlary fconductors rconnecting theA endsrof .-tisaid isecondaryiconductors lremote: from said .iur-

f 5 irther; `cor-mluctors tor-completely close' .thestrucv ...turez ot saidrzradatingi members, and means ito :icou-plea airtra'nsmissionrliner tof'said further conductors wat: :points :intermediate l the ,f-:collnearly arranged conductors.

L supportingmemberfand a pair of .radiating mem- -berssfsaidfradiating::membersv lbeingA constituted Thy. alpairi oi.v conductors arranged; adjacent 4and parallel` to -saiclsupportingI member., said'con-ducl5 tors beingv 'connectedtogether at the ends there- 1-cfe-througl1' theintermediarygof said conductive fffsupporting-flmembemand: a plurality :of further -conductorsrarranged .ina a. single l plane. and.` noranal to'ithe!rstssaidzconductors; `said further con- 20.=ductorsahaving11engths Marying .'from; ar minimum rati.thetfcentralz-.partzr.oit the-rstsaid 'conductors UTtot`Y almaximumnear the lends fof fthe first-said i:rconductors, fsaidtturther; conductors .'offmaxirrnxm length t: being substantially z a half Wavelength 251apa'rirf 'at'.ther.fopierating"A frequency;A and tertiary 'slconductorsz connecting theends of said `second- .,-fary' conductors'u'emotelvl fromz'saidi further con- "J ductorsf-to'wicompletelylclose thefstructure` tof l"said .flradiatingrmembersf and means fto couple. av trans- *aintermediate the lengthsthereof.

25. An antenna comprising a pair. 'of wing-like elements lying Tin: the= same'- 'yertical plane; each F wing" having a" lverticalf :edgeyfthe edges v`of 'each Lolo1fpa-irfilyingv relatively fclose-2'- together,= each #wing quencyrand-lthe;minimum width.` of 'the 'antenna eras measurediacross its` central portionin a horiezont'al direction-being 'otlthe order 'of one-quarter-l'wav`e1en`gth "atlfsa'id desired operating 'fre- L'quencyg:connections connecting together the 'top Tandr-bottomedgesoffsaid wing-like antenna elel.: ments,Y 1- a, zplurality of symmetrically arranged :rconductors connecting the recessed edgel 'of each "i antenna; 'element -tofthe lvertical edge vthereof 'and means for fconnec'ting `points located substantially :4eentr'a1ly1 of said-*vertical lbases to atwo con- Jiductor.transmissionlline ment and-being' further characterized by the fact "that` theres'aref a 'plurality of-symmetrically ar- "ranged" Aconductors" connecting points Von said're- Lcessd edge 'ther 'than s'aid central point toopi. posite, polnts on-fthe straight .line edge.. bfV each ahtennaelement. '27 An antenna Acomprising two pairs of symmet- 70, rical..Winglikeelements, each winghaving. a vertical..edg,e,`,.the. edgesbi each. pair. lying relatively ,closetogether, -each\-wing,having .top and bottom basesiand, a recessed edge-connecting vthe top and .bottorrebases-lthe overall height of said. symmet- ,75 .frical'iantennaaelementsf beinggreaten V.than ionehalf wavelength and less than one Wavelength at a desired operating frequency, the maximum width of the antenna, as measured in the direction of said bases being of the order of one-half wavelength at said desired operating frequency, and the maximum width of the antenna as measured across its central portion in the direction of said bases being of the order of one-quarter wavelength at said desired operating frequency, connections connecting together the top and bottom bases of said wing-like elements, a plurality of symmetrically arranged conductors connecting the recessed edge of each antenna element to the Vertical edges thereof, and means for connecting points located substantially centrally of said vertical edges to a two conductor transmission line.

28. Apparatus as claimed in claim 27 characterized by the fact that a conductor is provided for connecting the mid-point of the recessed edge of each antenna element to the mid-point of the straight edge of each antenna element and being further characterized by the fact that there are a plurality of symmetrically arranged conductors connecting points on said recessed edge other than said central point to opposite points on the straight edge of each antenna element,

the elements of one pair lying in one plane and the elements of the other pair lying in a different plane perpendicular to the rst mentioned plane.

29. An antenna operable over a broad frequency range and suitable for use in television service, comprising a pair of antenna elements lying adjacent each other in the same plane and being of substantially the same size and configuration, the over-al1 shape of both elements being generally that of the cross-section of an hourglass, each of said elements having a substantially straight conductive edge, top and bottom conductive bases, and a recessed conductive edge opposite the straight edge, said conductive edges and bases being connected together, short low impedance connections connecting the remote ends of the straight edge of one of said elements to the remote ends of the straight edge of the other of said elements, the maximum over-al1 width of the antenna being of the order of one-V half wavelength at a desired frequency of operation, the minimum width of the waist of said antenna at the desired frequency of operation being of the order of one-quarter wavelength and the length of said antenna as measured along one of said substantially straight bases being less than one wavelength and greater than one-half Wavelength at said desired frequency of operation, and a plurality of symmetrically arranged conductors connected to and between the substantially straight edge of each antenna element and the recessed edge thereof.

30. An antenna as claimed in claim 29 characterized by the fact that said symmetrically arranged conductors include a conductor connected from the center of the straight base of each element to the center of the corresponding recessed edge of each element and a plurality of additional conductors connected to the recessed edge and straight base of each antenna element and lying between the top and bottom edges of each of said antenna elements.

ROBERT W. MASTERS.

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

UNITED STATES PATENTS Number Name Date 1,289,685 Danielson Dec. 31, 1918 1,612,635 Hart Dec. 28, 1926 1,658,761 Crance Feb. 7, 1928 1,724,894 Batie Aug. 20, 1929 1,960,006 Hagen May 22, 1934 2,064,585 Atienza Dec. 15, 1936 2,086,976 Brown July 13, 1937 2,210,491 Lewis Aug. 6, 1940 2,298,449 Bailey Oct. 13, 1942 FOREIGN PATENTS Number Country Date 877,658 France Dec. 14, 1942

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