US2516706A - Antenna system - Google Patents

Description

July 25, 1950 E. A. LAPORT 2,516,706

ANTENNA SYSTEM Filed May 251947 2 Sheets-Sheet 1 BYZM July 25, 1950 E. A. LAPORT 2,516,706

ANTENNA SYSTEM Filed May 23, 1947 2 Sheets-Sheet 2 w; INVENToR.

rfo/m/Ex Patented July 25, 1950 ANTENNA SYSTEM fEdmund A. Laport, .Glen Ridge, N. J., assignor to Radio Corporation of Americaya corporation of Delaware Application May 23, 1947, SerialiNo. 50,145

( Cl. `Z50- 33) =Claims. l

The present invention relates rto yantenna systems 'and .more yparticularly vto -an antenna system 'for radiating a substantially uniform lield in .all :directions Vtoward the `:horizon and with substantially equal lcomponents -of vertical and horizontal polarization.

.An object of vthexpresent invention istoprovide an Y antenna f system for simultaneously radiating vertically and horizontally :polarized energy.

Another object 1oi'thefpresent invention :is ithe provision of van antenna .system 'as aforesaid which .radiates both 'elds :substantially uniformly inall directions `towardztl'ie horizon.

Another object ofithe ,present invention Yis to provide anovel form .fof vbbroadcast antenna.

Still anotherziobject. of vthe :present Yinvention is to provide a veryhighfrequencyantenna suitable for radiating airport .traffic controlsignals.

Still a further object :of the @present invention is the provision of an -,antenna,system (for simultaneously radiating vertically land horizontally polarized energy, said `antenna being simple and rugged in construction.

The foregoing objects and others `Which may appear from thefollowing detailed description are attained byproviding.y a turnstilejantennaarrangement having both vertical. and Ahorizontal radiating elements. The'radiating-elements are so energizedas to radiateiafrotatingeld offsubstantially uniform amplitude in 'all horizontal directions.

The present invention 4will be =more iully 4,understood by reference ,to .the following ydetailed description which is accompanied by a ,drawing in which:

Figure 1 illustrates in perspective View a simplified ,arrangement :of r an antenna :utilizing the principles of thepresent'invention, While Figure2 is an elevationaltviewiof:theantenna of the present invention, and

Figure 3 is aplan view thereof, while Figure 4 is a representation of rthe radiated lield distribution for-both 'vertically and .horizontally polarized fields.

Referringnow to Figureltherejs shown apair of crossed horizontal dipoles.NS and -WE. The dipole NS is fed near its, `center'pointlbv atransmission line loop It ofany convenient length. Toa selected point on loop l=isgconnectedone end of a second loop:20,' the point of ,connection of said-.second loop being .so cliosenxthat the diierential lengths of the. conductorsgof loop I0; from the. said` selected point. of connection. to the armsof dipole NS'isaihalfv-wavelength. ,Thus, the l tivov armsr of the vdipole NSxare :fed :.to L phase =2 opposition. Asimlar loop II, "having'fasimilar half wave differential in lengthstof connection from `its point Vof connection-to loop r2E! tto the arms "or" dipole vvWE, similarly fenergizes the arms of dipole 4WE in phase-opposition. fThe antenna is fed -from -a suitable Vsource of energy, not shown, by La ltransmissionline connected to la point on'loop 2U such :that-the differential "conductor -length yfrom fthe point of Aconnection of line TL to the loops illlfand I I Yis-aquarter-wavelength. Thus, kthe -dipole NS is fed in a phase quadrature relationship -to the dipole AA rotating horizontally -polarized-eld 2is, therefore, radiated from the turnstile :comprised 4of they crossed dipoles LNS and'W E. .It `should :be noted that, in connection with .the fforegoingdescrip.- tion, for Vthe sakefof.simplicitvithe winner-.com ductors only of theconcentricltransmission lines, forming loops fIIJ, II Yand 20, have `.been shown. Ordinarily lin practice, vthese .conductors will 'be surrounded by `concentrically arrangedgroun'ded conductive sheaths. Now, in order to compress the .radiation :into la :narrow vertical angle, a second .pairsof crossed ,dipoles 1N. S' and Wfl?! sis provided. These are arranged parallel to-.theil'i-rst mentioned dipoles .NS 4and E zand `-energized g in an -in-phase .relationship as indicated v.by the arrows land II'.. The arrows I. are ='shovvn.do.tte d in :order .to l.indicate .that while the f currents dipoles WE zand Wi." `are in vphase .with each otherithey are not in `an Ainfphase .relationship With.- fcurrents: Ia in dipoles .N S and N'S butprather ina..phase quadrature relationship ;Now,.1con sidering the dipole NS and :the dipole f NfS', these dipoles arespaceda half waveapa-rtl in.; a vertical planeand are. energized zin;,an:in,phase relationship. Thus, vthey fact. as sa `simple broad-side array.-fandctend; to gcompressthe verticalianglerof radiation. The-same effect'takesplace Withirespect to the dipoles WE and WE. Phasing con-1 ductors I5 are provided connecting vthedipoles NS and WEa-to theldipolesgNSandWE. Since the conductor lengths of zthephasing conductors I;5 arefof the ordersof vafhali -Wavelengthhthey must be. crossed gas indicated ,in oitder .to insure the, correct"` phase relationship of the currents in the dipoles. No.w, in.-,orderftoprovide anfequal.

component of verticalradiation, the fourvertical.

dipoles .'NN', 'WW2 SS ,and EE vare --provide d. Theyialte cach,conductivelvonnected at one end, inthe. present ,case,1theupper end,' to\i.one :of A.the horizontal turnstile @elements lwhereby ithey .are energized-fby1-direct :c onduction;.therefrom ?Now, at any given instance, :verticalfdipole vNNf fis energizefb in. an anti-phase:irelationship- .withsth'e vertical dipole SS. The two dipoles being spaced a half wave apart, they act as a simple end-fire array compressing the radiation in a direction in the plane of dipoles. However, as the four vertical dipoles are energized in progressive phase quadrature relationship, the radiation pattern rotates in a horizontal plane at the frequency of the radiated wave and a substantially uniform rotating iield of vertically polarized energy is provided.

The actual mechanical construction of an antenna constructed according to the principles of the present invention is shown in Figure 2. It will be seen that all of the radiating elements are constructed of hollow pipe an'd fittings whereby the entire structure may be electrically grounded for protection against lightning strokes. The dipole WE is supported at its mid point by a tubular metal supporting pole 30 provided at its lower end with a suitable mounting flange 3i. The transmission lines TL, by means of which the antennas are energized, pass vertically through the supporting pole 30 and out through suitable apertures at the top end thereof where` their inner conductors are attached at pointsl along the lengths of the dipoles such that the impedance of the dipoles is matched to the impedance of the transmission line loops. The vertical radiators are conductively connected to the upper horizontal dipole by elbow iittings 4E) and are supported at their voltage nodal points near their centers by conductive tubular members 42 securely attached to the supporting pole.

3|). The arrangement of the phasing conductors l5 by means `of which the lower turnstile is energized from the upper turnstile is more clearlyshown in Figure 2 than in the simple diagrammatic representation in Figure l. The interlacing of the conductors l5 to provide the correct phase relationship and to avoid the conductive supports 42 is apparent from the drawing. I

A calculation of the antenna shown in Figures 2 and 3 resulted in the radiation pattern in Figure 4. Curve 5B shows the relative amplitudes of the vertically polarized field for varying angles of elevation while curve 52 similarly depicts the distribution'of the horizontally polarized field in the vertical plane. `ln the horizontal plane, both` fields are substantially circular in pattern so no graphical representation is necessary. While'I have illustrated a particular embodiment of the present invention, it should be' clearly understood that it is not limited thereto since many modifications may be made in the several elements employed and in their'arrange-- ment and it is therefore contemplated by theA appended claims to cover any such modifications as fall 'within the spirit and scope of the invention. v

What is claimed is:

l. An antenna system including a first pair of crossed dipole' radiators supported at its midpoint on a vertical conductive mast, a second pair of crossed dipoles supported at its midpoint' on said mast at a distance equal to a half of the operating wavelength from said first crossed dipoles, means for feeding said iirst pair of crossed dipoles with radio frequency energy in a phase quadrature relationship whereby a rotating horizontally polarized eld is radiated, means for feeding said second pair of crossed dipoles from said first pair and a vertically arranged dipole connected to each end of each'of said first pair of vcrossed dipoleswhereby saidvertically ar-f fir' ranged dipoles are arranged to radiate a vertically polarized rotating iield.

2. An antenna system including a first pair of crossed dipole radiators supported at its midpoint on a vertical conductive mast, a second pair of crossed dipoles supported at its midpoint on said mast at a distance equal to a half of the operating wavelength from said iirst crossed dipoles, means for feeding said first pair of crossed dipoles with radio frequency energy in a phase quadrature relationship whereby a rotating horizontally polarized field is radiated, means for feeding said second pair of crossed dipoles from said first pair and a vertically arranged dipole connected to each end of each of said first pair of crossed dipoles whereby said vertically arranged dipoles are arranged to radiate a vertically polarized rotating field, said first pair of crossed dipoles beingabove said second pair and said vertically arranged dipoles depending from Lsaid first pair of crossed dipoles.

3. An antenna system including a vertical conductive mast, a group of dipole radiators arranged in cruxiform and supported on said mast, a second group of dipoles arranged in cruxiform and supported on said mast at a distance equal to a half of the operating wavelength from the rst mentioned dipoles, means for feeding said first group of dipoles with radio frequency energy in a phase quadrature relationship whereby a rotating horizontally polarized iield is radiated, conductorsarranged for feeding said second group of dipoles from said iirst group of dipoles, and a verticallyarranged dipole connected to the outermost end of each of the dipoles of said first group whereby said vertically arranged dipoles radiate a vertically polarized rotating field.

4. An antenna system including a first group of dipole' radiators supported at one end on a vertical conductive mast, a second group of dipoles supported` at one end on said mast at a distance equal to a half of the operating wavelength from said first group of dipoles, the dipoles of said groups-being arranged in oruxiform, means to apply radio frequency energy in a phase quadrature relationship to the dipoles of said first group whereby a rotating horizontally polarized field vis radiated, conductors tapped onto the dipoles of said second group of dipoles at points intermediate theends thereof and arranged to apply energy thereto from the dipoles of said first group, and a vertically arranged dipole connected to the outermost end of each of the dipoles of said first group whereby said vertically arranged dipoles radiate a vertically polarized rotating field, said rst group of dipoles being above said second group and said vertically arranged dipoles depending from said first group of dipoles.

`5. An antenna system including a vertical conductive mast, a group of dipoles supported at one end on said m-ast in conductive relationship thereto and extending outwardly therefrom for a distance of substantially a quarter of the operat- -ing wavelength, a second group of dipoles supported at one end on said mast in conductive relationship thereto and extending outwardly therefends to' apply radio frequency energy in a phaseI quadrature relationship whereby a rotating horizontally polarized field is radiated, conductors interconnecting kpoints onthe dipoles of said first group intermediate the ends thereof with points on said second group intermediate the ends thereof to feed said second group of dipoles from said rst group and ka vertically arranged dipole connected to the outermost end of each of the dipoles of said rst group whereby said vertically arranged dipoles are arranged to radiate a vertically polarized rotating eld, said vertically arranged dipoles depending from said rst group of dipoles.

EDMUND A. LAPORT.

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

Number 6 UNITED STATES PATENTS Name Date Lindenblad Apr. 16, 1940 Lewis Aug. 6, 1940 Lindenblad 1 Oct. 15, 1940 Aram Jan. 4, 1944 Wheeler Feb. 18, 1947 Marchand 1 Sept. 2, 1947

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