US2298449A - Antenna - Google Patents

Abstract

560,271. Wireless signalling. STANDARD TELEPHONES & CABLES, Ltd. Nov. 6, 1942, No. 15701. Convention date, Nov. 8, 1941. [Class 40 (v)] An antenna system for radiating or receiving with equal intensity in all directions in a given plane comprises a pair of elongated sheet conductors 90, 91 spirally disposed around a two-conductor transmission line, each sheet conductor being connected along one longitudinal edge to a different conductor of the line. The sheet conductors may be regarded as surfaces generated by rotating an elemental dipole antenna about the axis of the line, and simultaneously moving it along the axis to provide a plurality of like antenna sections in which the spacing in angular degrees between any two assumed positions of the elemental antenna is equal to the spacing in electrical degrees between the points of connection of the elemental antenna to the line conductors. The transmission line may comprise a vertical mast with inner and outer conductors 101, 102 or two vertical masts each forming one conductor, Fig. 4 (not shown). The structure is earthed at its base through a quarter-wave-length line section 17 to provide a low impedance for lightning and frequencies other than the operating frequency. Reference is made, for explanatory purposes, to an " expanded turnstile " array, Figs. 1 and 2 (not shown), comprising four sections-,- each having six dipoles displaced vertically and angularly by equal amounts. The Specification, as open to inspection under Sect. 91, also describes other " turnstile " arrangements. In one, dipoles arranged; a quarter-wave-length apart and in space quadrature are connected to corresponding points in a transmission line constituted by a hollow flag pole serving as the outer conductor and supporting an inner conductor, Figs. 1 and 2 (cancelled, not shown). In a modification, Fig. 4 (cancelled, not shown), the transmission line comprises two separate masts. In a further modification two transmission lines comprising four vertical masts are used, the phase of the energy in one line being displaced 90 degrees from that in the other, Fig. 5 (cancelled, not shown). This subject-matter does not appear in the Specification as accepted.

Description

A. B. BAILEY Oct. 13, 1942.

ANTENNA Filed Nov. 8, 1941 3 Sheets-Sheet 2 HORIZON TAL PL ANE CHARAC TEP/5 TIC FOR SYSTEM OF FIG. 6

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A 7` TOR/VE V Patentecl Oct. 13, 1942 ANTEYNA Arnold B. Bailey, Scotch Plains, N. J., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application November 8, 1941, Serial Nol. 418,363

12 Claims.

This invention relates to antenna arrays and more particularly to omnidirectional short wave and ultra-short wave antenna arrays.

As is known, in the short and ultra-short wave fields including the frequency modulation broadcast eld. arrays comprising two sets or vertical panels of horizontal doublets, the doublets in each panel being vertically spaced and the panels being included in quadrature vertical planes, have been suggested for achieving radiation in substantially all directions in the horizontal or azimuthal plane. Patents 1,937,748, H. R. Darbord, December 5,- 1933, and 2,234,744, H. P. Thomas, March 1l, 1941, each disclose a staggered or semiturnstile array in which the horizontal tiers each include a single series-excited doublet and in which the doublets in the adjacent tiers are positioned in space quadrature and energized in time quadrature. Patents 2,086,976,G, H. Brown, July 13, 1937, and the copending application of J. F. Morrison, Serial No. 335,663, filed May 17, 1940, and assigned to applicants assignee, illustrate respectively, a shunt-excited and a series-excited turnstile array, in which each horizontal tier contains two doublets positioned in space quadrature and energized in time quadrature, the adjacent tiers being substantially identical. As is apparent, the radiations for all of the substantially infinite number of horizontal directions are not always the same in these prior art systems, since each doublet has a figure-of-eight directive diagram and the overall directive characteristic of the two adjacent quadrature doublets is a fourleaved clover similar to that utilized in the wellknown A-N Beacon system. It now appears desirable to obtain in a system employing, as in the above-mentioned systems, horizontal polarized waves,'a more uniform radio emission and response in the azimuthal pla-ne than heretofore realized and, at the same time, to employ antenna structure having distinct mechanical and electrical advantages not found in the prior art systems.

Itis one object of this invention to obtain in a radio system utilizing waves polarized in a given plane, uniform transmission and reception in said plane. v

It is another object of this invention to secure an omnidirectional, and substantially circular, horizontal plane directive characteristic for a horizontally polarized antenna.

It is still another object of this invention to employ relatively simple self-supporting antenna structure, for securing azirnuthal omnidirectional radio action, which structure is connected vto the earth through a path having zero impedance, substantially, for lightning current and a high impedance at the operating frequency and which is easily assembled or dismantled and readily altered for the purpose of effecting a change in its operating quality.

In accordance with one embodiment of the invention, the antenna structure comprises discrete horizontal collecting or emitting members attached to a metallic flagpole type mast at points vertically spaced a quarter wave-length, these members being energized in time quadrature and positioned in space quadrature. The flagpole mast is grounded at its base and constitutes one line conductor, the mast being connected to the main transmission line from the transmitter or receiver at a point a quarter wave-length above its base. The quarter wave line section at the base has a negligible impedance for lightning and a high impedance at the operating frequency. In accordance with a diierent embodiment one or more additional discrete horizontal members are attached to the mast, each at a point located between the above-mentioned vertically spaced quadrature members. The direction of extension and the phase of the current supplied to each intermediate element are related to the distance along the mast between the added intermediate member and either of the first-mentioned quadrature members.

In accordance with a preferred embodiment of the invention, the antenna structure comprises a grounded metallic vertical mast constituting one line conductor and enclosing the other line conductor and a pair of vertical spiral radiating or collecting sheet conductors each having a suitable horizontal width as, for example, a half or a quarter wave-length. Each sheet is joined along a longitudinal edge to a different line conductor, the path or junction line between each sheet conductor and the associated line conductor being spiral in contour. 'Ihe pitch, that is, the length of each portion having a complete twist or spiral, as measured along the vertical line conductor, is one wave-length. Every horizontal plane intercepting the mast or vertical line and the attached spiral sheet conductors includes an effective dipole antenna and, similarly, every vertical plane containing the line conductor includes a dipole antenna, the spirality being so dimensioned relative to the vertical line or mast that the effective dipoles vertically spaced a quarter wave-length are in space quadrature and energized in time quadrature. In a sense, whereas the prior'art structures comprise discrete dipoles, the spiraliform antenna of the invention isa continuous or expanded tumstile structure or spiraloid analogous to a double circular ramp or an Archime- Y dean screw and comprising. non-discrete doublets of infinitesimal vertical thickness, the non-discrete adjacent doublets in contiguous vertical planes and the doublets in adjacent horizontal planes being energized with currents having an infinitesimal phase difference, whereby the array has. in each horizontal plane or tier, a gure-ofeight diagram and by virtue of the juxtaposition' of the differently oriented doublets, the effective azimuthal diagram is a true circle.

The invention will be more fully understood from a perusal of the following specication taken in conjunction with the drawings on which like reference characters denote elements of similar function and on which:

Fig. 1 illustrates a semiturnstile or staggered antenna array comprising a single mast: Fig. 2 is a partial detail view of the system of Fig. 1 and Fig. 3 is a directive diagram for the system of Fig. 1; Fig. 4 illustrates a semiturnstile array comprising two masts which constitute the transmission line; Fig. 5 illustrates a turnstile array comprising four vertical masts; Fig. 6 is a perspective view and Fig. '1 a plan View of a circular ladder type array comprising expanded turnstile sections and discrete dipole members and Fig. 8 is a directive diagram for the array of Fig. 6, and Figs. 9 and 10 illustrate spiral arrays comprising respectively, a single flagpole mast and two ilagpole masts; Figure l1 shows the hori- -zontal plane characteristic for systems' of Figures 9 and l0.

Referring to Fig. 1, reference numeral I designates a .hollow fiagpole type mast constituting the outer conductor of a coaxial line 2 and reference numeral 3 denotes the inner conductor of the line, the mast I being tapered as illustrated and the inner conductor being preferably of tapered 4pipe construction asshown by the exposed view in Fig. 1. Insulators (not shown) are utilized to maintain the inner and outer conductors of line 2 `spaced from each other. Numerals l and 5 south and east-west dipoles or doublets each of which comprises a quarter wave-length member B electrically connected to-the mast I and a quarter wave-length member 1 connected to the inner conductor 3. The adjacent doublets l and 5 are perpendicularly related so that the four quarter wave-length members. included therein extend in quadrature 4directions preferably, .but not necessarily, coinciding with'the cardinal compass points, 4N, E, S and W. The N-S doublets are included in the same vertical plane and constitute one aerial panel 8 and the E-W doublets are includedin a vertical plane perpendicularly related to the above-mentioned plane and conlstitute. another aerial lpanel 9. The adjacent dipoles in each. of panels 8 and 9 are vertically' spaced a half wave-length apart along the vertical transmission line 2 and are transposed. Thus, considering any two adjacent dipoles l of nected to the line 2 at points spaced a quarter wave-length apart. Hence, the four quarter wave-length members constituting each pair of adjacent dipoles 4 and 5 are connected to the line 2 forenergization in phase quadrature. For' convenience, the respective phases of the N, E, S and W quarter wave-length members are assumed to be 0, 90, 180 and 270; and each pair of adjacent dipoles I and 5 is designated an antenna section. Reference numeral I 0 denotes a coaxial line having an outer conductor Il and an inner conductor I2, and connected between device I3 and the line 2 at a point I4 a quarter wave-length above the mast base I5. 'I'he line 2 is short-circuited at the base I5 by the ground conductor I8 and the quarter wave-length line section l1 constitutes a high impedance at the mean operating frequency and substantially zero impedance at other frequencies as, for example, lightning frequency. Also the line 2 extends a quarter wave-length above the top dipole and is shortcircuited at the top extremity. The ground I6 may be actual earth or the metallic top of a building or other structure.

As shown in Fig. 2 which illustrates certain mechanical features of the system of Fig. l, the. half dipole members 6 are preferably of light4 weight tubular construction and are each equipped with a threaded plug 20 which is adapted to fit into'a properly located threaded socket 2| on the mast I, whereby a solid electrical connection is established between each radiating member and the mast and a relatively strong mechanical junction is eifected. Similarly, properly spaced threaded sockets 2| are provided in the inner pipe f y obvious, other mechanical connections as, for ex- -designate, respectively, half wave-length northample, plug and jack assemblies, may-be satisfactorily utilized in place of the above-described connecting-assembly. The mechanical arrangement 'is such that the projecting quarter wavepanel 8, themember 6 of one dipole and the member 1 of theI other dipole have the same pointdirection but are connected to'different line'con- 'ductors at points spaced a half wave-length along and 5 are positioned in space quadrature and conlength members may easily be removed forthe purpose of facilitating transportation'to the place of assembly and erection. Also, sections comprising a pair of adjacent dipoles 4 and 5 may be readilyremoved or added for the purpose of altering the receiving quality or radiating power capacity of the system.

Referring to Fig. 3, the operation of the system of Fig. 1 and Fig.v 2 will now be explained. Assuming the translation device I3 is a transmitter, radio energy of the given operating frequency is supplied over line Ill to the line 2 and in proper phase to the four quarter wave-length radiating members C, 1 constituting each antenna section. As already indicated, at the junction point Il 'oflines I0 and 2, the short-circuited wave-length transformer I1 effectively prevents energy of the operating frequency from flowing propagated on1y in the N, s, E and w directions.

similar to the array of Fig. 1 from an electrical and radiant standpoint but which includes certain mechanical features not present in lthe system of Fig. 1. Numeral 40 designates an open conductor line comprising vertical masts 4I and 42 held, if desired or necessary, in spaced relation by the short-circuiting block member 43 positioned at the top extremity of line 40 which point is a quarter wave-length removed from the uppermost dipole. As in Fig. 1, numerals 4 and 5 designate dipoles included in the N-S panel and the E-W panel, respectively, the quarter wave-length half-dipole members 5 being connected to the same pole or line conductor 4I corresponding to the outside conductor I in the system of Fig. l and the members 'I being connected to the other dipole conductor 42 corresponding to the inner conductor 3 of Fig. 1. Considering each of pole conductors or masts 4I and 42, the half-dipole members are vertically spaced a quarter wave-length and the adjacent quarter members are in spaced quadrature. The transmission line I from device I3 is connected to the line 40 at a point I4 which is a quarter wavelength above the base I5 of each mast. As in the system'of Fig. l, the quarter wave-length dipole members 8, l are equipped with threaded plugs for attachment to threaded sockets in the mast conductors 4I and 42.

In operation, Fig. 4, energy is supplied from device I3 to the various dipole members in proper phase relation and the resulting directive diagram is substantially the same as that of the systemV of Fig. 1. From a mechanical standpoint the system of Fig. 4 may be preferred for certain, but not necessarily all, usages since the coaxial line insulators and the aperture insulators 22 used in the system of Fig. l are not required, the poles 4I and 42 are not mechanically weakened by reason of apertures and the vertical open type line is more easily maintained in an operative condition. On the other hand, the embodiment .of Fig. 1 possesses certain advantagesfrom the standpoint of sleet formation and ease of transportaticn.

Fig. 5 illustrates a stack array comprising eight turnstile tiers or sections 50 vertically spaced a quarter wave-length and a pair oftransmission lines 5I and 52, the sections 50 each comprising a pair of doublets 4, 5 and the lines 5| and 52 each comprising two tubular or pipe-type 'conductors designated 53, 54 and 55, 56, respectively. 'I'he vertical mast conductors form la columnar structure 51, which extends to the ground I6 and `the four vertical conductors constituting the column are held in spaced relation by insulators 58. At point I4 a quarter wave-length above ground I6 lines 5I and 52 are connected through separate branch lines I0 to a main line I0 and associated translation device I3, a quadrature phase shifter 59 being included in the branch line I0 connected to the vertical N. S, E or W half dipoles in alternate turnstile sections 50 are connected to diiferent conductors 'for in-phase energization.

oi' the same vertical line and hence are arranged e corresponding half-dipole members in adjacent sections 50 are connected to conductorsoi' diil'erent lines and,

since these lines, 5I and 52, are connected to ,de-

vice I3 for'quadrature energization and the lengths 'of the two lines from device I3 to the adjacent sections dier a quarter of a wavelength, these corresponding members are connected for in-phase energization.

In operation, Fig. 5, assuming device I3 is a transmitter, energy of the operating frequency is supplied over main line III and the branch lines I5 to .the vertical lines 5I and 52 and to the turnstile sections 50. `The phase of the energy delivered to line 52 is shifted 90 lrelative to the energy of line 5I by means of thequadrature phase shifter 59. Considering each turnstile section 50, the energies supplied to the two halves of each dipole are oppositely phased and the currents delivered to the two dipoles are in phase quadrature whereby the four half dipoles are, as in the systems of Figs. y1 and 4, energized in quadrature and the corresponding half-dipole members in the array are energized in phase. Also, as in the systems illustrated by Figs. 1 and 4, the currents of the operating frequency sup- L, rents. The resulting horizontal plane array charline52. The corresponding,

a more concentrated beam plied to` lines 5I and 52 are prevented from leak- -ing to ground I6 by means ofthe separate quarter wave-length short-circuited transformers I 1 connected between the ground II and point I4 on each of lines 5I and 52 and each line conductor 53, 54, 55, 56 is grounded for lightingl and other frequencies differing from the operatingl frequency as, for example, even harmonic curacteristic for the system of Fig. 5 is the same as that of the semiturnstile array of Figs. 1 or 4, as illustrated by Fig. 3. The array of Fig. 5, however, has a more desirable vertical plane characteristic since the additional radiators produce and a lower angle of fire. If desired, complete turnstile sections 5I) may be added to or removed from the system of Fig. 5 in order to conform with particular power or height requirements.

Fig. 6 illustrates a stack four expanded-turnstile sections 60 and each section comprising six discrete doublets 6I. The doublets are connected in series with the coaxial line 2 which comprises mast `I and inner conductor 3. Line I is connected at a point a quarter wave-length above ground I6 to the main line I0 and the device I3. Considering any two adjacent doublets 62 in the array, the doublets are positioned in parallel horizontal planes andl in angularly related vertical planes, and the spacing A -in electrical degrees between the above-mentioned-horizontal planes as shown in Fig. 6 is the same as the dihedral angle B in angular degrees between the aforementioned vertical planes, as shown in Fig; 7, the value ofA A and B being 12 for the system illustrated by Fig. 6. More generally, while in the system of Fig. 6 each staggered turnstile section 60 contains six dipoles, it should be understood ythat in accordance with the invention a complete turnstile section 60 may comprise n dipoles 6I, n being any number greater than 2. The equation given below gives the relation between the Value of the angle B (and spacing A) and the number n of dipoles in a section 6I):

array each comprising with n equal to 2 the above equation applies to the simple staggered arrays of Figs. 1 and 4, since each semiturnstile section in these systems comprises two dipoles in space quadrature. While, ordinarily, the angle 'B is less than,90, it may be increased by a multiple, including the integer I, of a wave-length. Also, while the dipoles, as viewed from the base I5, are successively displaced to the right, that is, in a counterclockwise manner, they may be displaced if desired in a clockwise manner. As inthe system of Fig. l, plug and socket connections are preferably used for attaching the quarter wave-length dipole elements to vthevertical line conductors I and 3. l

In operation, referring to Figs. 6, 7 and 8, device I3 supplies oppositely phased energies to the two halves of each dipole 6I. dipoles are connected to points spaced )./12 on the line 2, the currents in these dipoles have a phase difference equal to 12 and, since the adjacent dipoles are positioned at an angle of 7\/ 12, their figure-of-eight diagrams greatly overlap. Fig. 8 illustrates the horizontal twelve-leaved rose directive characteristic of each turnstile section 6I As may be seen by comparing the four-leavedvrose of Fig. 3 with the twelve-leaved rose diagraml of Fig. 8, the expanded array of Fig. 6 produces more uniform radiation in a horizontal plane than is produced by the systems of Figs. 1, 4 or 5, the system of Fig. 1 having only four points of equal radiation whereas the system of Fig. 6 has twelve. Moreover, the difference in intensity between any of the maximum iields 63 and any of the minimum iields 64 is less in the case of the system of Fig. 6 than the diierence, Fig. 3, between any of the maximum N, E, S and W iields and any of the minimum NE, SE, SW and NW ilelds for the systems of Figs. l, 4 and 5. If desired, additional dipoles may be attached to the line 2, Fig. 6, between any pair of adjacent dipoles, the compass or point directions and the points of attachment to the transmission line 2 of the added doublets being selected in accordance with the above equation. For example, an additional dipole may be added to the line at a point midway between the two bottom doublets 6I of Fig. 6, the additional doublet being included in a vertical plane making an angle of 15 with each of the two dihedral vertical planes containing the aforementioned bottom doublets.

Fig. 9 is a perspective view and Fig. 10 is an elevational view of an array comprising two spiral radiating metallic sheet conductors 90 and 9|, the array of Fig. 9 being connected to, and supported by, an open mast type line and the array of Fig. 10 to a coaxial mast type line. In appearance the spiraloid of these gures resemble a double circular ramp or an Archimedean screw. Referring to Fig. 9, the sheet conductors 90 and 9| are attached to line conductors 92 and 93 which constitute a vertical self-supporting line v 9.4. Reference numeral 95 designates suitable insulators for maintaining the line conductors 92 and 93 insulated from each other. At a point I4 a quarter wave-length above the ground or other conducting surface I6, the line 94 is connected to line I and device I3, the lower portion I'I of line 94 constituting a short-circuited quarter wavelength line. Each of radiating sheets 90 and 9| makes two complete spirals around line 94, each complete spiral or subarray having, as shown in Fig. 10, a vertical height of one wave-length and a horizontal width ofa quarter wave-length. Each sheet contains an inilnite number o f horizontal, non-discrete, adjacent elemental doublets 91, which have an innitesimal thickness in the vertical and horizontal planes. The segmental 'or elemental doublets in each sheet located at and between points vertically spaced a quarter wavelength along the line form a turnstile section 90. Considered from another standpoint, the array of Fig. 9 corresponds to thev surface of revolution generated by revolving a dipole about its center point and simultaneously moving the dipole along a linear path or axis, and is a structure which may be approximated by adding a sufficient number of intermediate properly spaced and properly oriented discrete doublets to the system of Fig. 6 so as to secure a substantially solid wash-board radiating surface analogous to a spiral or double circular ramp. Again, considering each turnstile Since the adjacent l section 96, Fig. 9, the every vertical plane passing through the transmission line 94 includes a separate elemental doublet, and each horizontal plane passing through the section 96 contains a separate elemental doublet.

Referring to Fig. `10 the doubler-amp array 90, 9| is associated with a coaxial self-supporting ilagpole type line I 00 which comprises inner conductor IOI and outer conductor |02. One longiby insulators (not shown).

tudinal edge of metallic sheet 90 is attached to the outer conductor |02 along a spiral junction line; and a longitudinal edge of metallic sheet 9| is similarly attached to the inner vconductor |0I. A' spiral slot |03 is provided in the outer conductor for permitting attachment of the sheet 9| to the inner conductor IOI, the sheet 9| being maintained spaced from the outer conductor |02 As in the systems previously described, the transmission line I0 from device I3 is connected to line |00 at a point a quarter wave-length above the ground I6.

In operation, energy is supplied by device I3 and line I0 to the line 94, Fig. 9, and to the line |00, Fig. 10, and thence radially to the sheet conductcrs 90 and 9|, the phases of the currents supplied to the contiguous, innnitesimally spaced, horizontal elemental doublets 91 in each sheet conductor having .a substantially iniinitesimal diiference. The'doublets are progressively phased fi'and the elemental doublets having a quadrature space relation'are energized inquadrature. Considering each turnstile section 96, since the con- Y tiguous doublets are displaced successively an iniinitesimal amount, the overall directive diagram vfor each of the systems of Figs. 9 and 10 comprises a large number, approaching infinity, oi' overlapping figure-of-eight diagrams and is circular, as shown by Fig. 11. Radiation of equal intensity occurs in all horizontal directionsl and, vas compared to the prior art systems and to the systems illustrated by Figs. 1, 4, 5 and 6, more desirable characteristics, horizontal and vertical, are obtained. All`parts of the structures of Figs. 9 and 10 are grounded for lightning and the selfsupporting structures are rugged and advantageous from a mechanical standpoint.

Although `the invention has been explained in connection with certain embodiments, it is to be understood that it is not to be limited to the apparatus illustrated, inasmuch as other equipment and apparatus maybe satisfactorily employed in practicing the invention. The antenna of the invention is equally well suited for receiving and transmitting and while the embodiments described produce equalized horizontal radio action of horizontally polarized waves, the invention may be utilized for achieving equalized radio action in any plane of polarization. If, as in airdicularly intercepting said line and port landing systems, equal radiation in the vertical plane of vertically polarized waves is de sired only one spiral sheet conductor is required since the ground image may be employed in place of the othersheet conductor.

I claim: f

1. An antenna for securing equi-intensity radio action in all directions in a given plane comprising a pair of sheet conductors each spirally twisted about one of its longitudinal edges and having both faces orsurfaces exposed to the ether medium, the corresponding transverse segmental portions of said sheet conductorsbeing included in a. planeV perpendicular to said first-mentioned plane and containing said edges substantially.

` 2. An antenna comprising two exposed spiral sheet conductors vertically positioned and con? nected in series through a translation device, each conductor having a uniform horizontal width and a pitch o1 a wave-length.

3. An antenna system for securing equal radio actions in all directions in a desired .plane of wave travel for Waves polarizedin said plane comprising a spiral sheet conductor connected along one edge to a line conductor extending substantiallyl in a direction perpendicular to said plane, said sheet conductor being spiralled once about a section of said line conductor having a length ofone wave-length.

4. An antenna system for securing equal radio actions in all directions in a desiredplaneof wave travel for waves polarized in said plane,

comprising a pair of line conductors insulated 'from each other and extending substantially in direction perpendicular to said plane, and a pair of spiral sheet conductors connected veach along one edge to corresponding portions of different conductors. f l

5. A system in accordance with claim 4, said sheet conductors each having one complete spiral `for each line section a wave-length long and extending at corresponding points of connection with said line conductors in opposite point-directionsr perpendicularly related spirally connected along a longitudinal edge to a different conductor,` whereby each plane perpento the, line connected continuously and spiially along one edge to corresponding portions of said line and each complete spiral -extending a wave-length along said line.

8. In combination, a vertical transmission line, an antenna array comprising-a plurality of vertically spaced doublets connected to said line and lpositioned in dierent vertical planes, the'spacing betwen adjacent doublets being less than a quarter wave-lengthA and electricaly equal to the angle between the vertical planes containing said adjacent doublet.

9. In combination, a transmission line, a plurality of linear antenna members connected thereto andspaced less than a quarter wavelength, said members being angularly'- displaced an amount equal to said space.

` 10. An antenna array comprising a pair of linear members connected to a line and positioned vin angularly related vertical planes and in different horizontal planes, the spacing in electrical degrees between said horizontal planes being less than degrees and equal to the dihedral angle formed by said vertical plane. l 1l. In combination, a translation device, a self supporting coaxial line comprising a vertical mast conductor and an enclosed conductor, a plurality ofperpendicularly related half wave-length horizontal doublets each comprising two onequarter'wave-length members, the membersA of\ each-doublet being connected in series with each other only through said conductors and device.

12. In combination, a self-supporting coaxial linecomprising a pair of rigid conductors, a. translating device, an antenna comprising a. pair of perpendicularly related doublets, said doublets being removably connected in series with said conductors and said device and each of said line conductors being connected to earth' through a path having a substantially lnnite impedance at theoperating frequency and zero impedance at other frequencies. l c

' ARNOLD B. BAILEY..v

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