US2630531A - Television antenna - Google Patents

Description

March 3, 1953 L, H. FINNEBURGH, JR 2,630,531

TELEVISION ANTENNA Original Filed Sept. 16, 1950 S C C5 C'4 C #T7 j l l z |NVENTOR 11 Lew'is H.Finnelrurgh Jr. in BY VM WMV ATTORNEYS Patented Mar. 3, 1953 UNITED STATES PATENT" (lFFICE` Original application September 16, 1950, Serial No.` 185,197, now Patent No.J 2,566,287, dated August 28, 1951. Divided and this application Y July 20, 1951, SerialNo. 237,806'` (Cl. Z50-33.5.7)4

Claims.. l

This invention relates to antenna systems and particularlyto high` gain, directive antennasys-v tems fortelevision transmission and reception.

The principal object of the invention is to provide a high-gain antenna system that4 will 'be responsive with almost uniform, maximum gain overa widerange of frequencies covering at least the range of the present high or low television bands, and that will be responsive with good performance overboth` the present. high and 10W bands:

Another object of the invention is to` provide an antenna system having the foregoing performance characteristics and having an aerial structure suitable for mounting on asingle, rotatable mast.

A further'object of the inventionisto provide an aerial structure-that may be` shipped in a completely assembled, collapsedA condition, and that maybe quickly extended in an. accordion-like manner at `the place of installation` for mounting on a mast to provide an antenna system ofthe character described.

Still another object of the invention is to ae,- complish vthe foregoing objectives while making the greatest possible structural use of electrically functionalmembers, `therebylreeping the amount of material in the aerial structure to a minimum consistent with the results to be achieved.

structurally, the aerial resembles two vertically stacked sets of three `half wave collinear units with quarter wave, phase reversing stubs,gone of the two sets being inverted with respect to the other to bring their stubs back to back, both sets being supported in laterally spaced parallel relationship Withrespect to apair of similarly stacked reflectoraand the whole being mounted on a vertical mast. Electrically, however, the antenna system differs radically from Such an assembly, and, in addition, possesses certain novel structural` characteristics` not immediately apparent from an` inspectiony of the complete assembly.

The principal electrical feature of the inventionsresides in` thediscovery that.l remarkable broadbandillg; effects are achievedwhen such a` vertically stacked pair of` back to back sets of collinear units have vthe adjacent ends of their oppositely disposed` stubs electrically connected, as by closingtheir ends with a common conductor. Antennas and antenna systems embodying this electrical feature of the invention are the subject of my copending application Serial No. 185,197, `led September 16, 195D, and granted asPatentNo.. 2,566,287, granted August 28,1951.

Thev principal structural feature of. the, Huren--` tionfresides in the employment of, pivotal connecev tions -at each corner of 4each individual stubl SQ i that each pair of oppositely disposed rectangular stubs having a common side may be collapsed, as`

folding parallelograms, to permit the two setsY of collinear units and reiiectors to be brought to.

gether for` packaging, pulled apart again attheplace of installation, and quickly .converted into i These` special features of the invention and various other objects and advantages thereof will be more fully understood from the following de tailed description of an illustrative embodiment` of the invention, taken in conjunction with. the accompanying. drawings, in which:

Figure 1 is a perspective view looking upwardly at an antenna embodying the invention;

Fig.` 2 is an end elevation on an enlarged scale ofthe aerial structure and mast of theantenna shown in Fig. 1, the view beingtakenY as indicated by the line 2-2 of Fig.V 1;

Fig. 3 is a fragmentary planvview on a further enlarged scale of the aerial structure and mast of Fig. 1, the View being taken as indicated. by the line 3-3 of Fig. 1.A

Fig. 4 is a fragmentary vertical section through the aerial structure` and mast of` Fig. 1, the View being on the same scale as Fig, 3 and taken as, indicated by the lines. 4 4 in Figs. 1 and 3;

Fig. 5.is another fragmentary plan view show ing a detail ofthe aerial of Fig. `1 on thescale of Figs. 3 and 4.

Fig. 6 is. a front. elevationof the detail,` of Fig. 5;

Fig.` 7 is` another, fragmentary, vertical section showing a detail of the aerialr of Fig. 1 on the lation with one inverted with respect to the other, this illustration being given for comparative purposes;

Fig. 11 is a similar, diagrammatic elevation showing the changes from Fig. that were most signicant in bringing about the improved electrical operation achieved by the invention.

Referring principally to Fig. 1 and to the details shown in Figs. 2 to '7, the aerial structure of the antenna system illustrated is carried by a single vertical mast I2, that may take the form of a rigid, hollow, metal tube mounted in any desired manner (not shown) for rotation about its vertical axis.

A top cross arm I3 and a lower cross arm I4 are mounted at their centers adjacent the top of the mast and extend horizontally in vertically spaced-apart parallel relation. The cross arms I3 and I4 may also take the form of hollow, metal tubes, preferably being made of a light metal and smaller in diameter than the mast I2, but large enough in diameter to remain substantiallly rigid while carrying the remainder of the aerial structure.

The cross arms I3 and I4 are rigidly secured to the mast I2 by suitable brackets, such as the one illustrated in detail in Figs. 3 and 4. In this illustrative embodiment, the bracket comprises a short, channel shaped member I9 extending horizontally and having notches I'I in its flanges for receiving the mast I2. The web or back of the channel shaped member I6 is formed with a longitudinally extending groove i8 therein to receive the cross arm I3 (or I4). The channel shaped member is secured against the mast and the cross arm is secured against the channel shaped meinber by a. U-bolt I9 that straddles the mast with its legs extending through aligned pairs of apertures in the channel shaped member and in the cross arm, and by a cooperating pair of nuts 2I and washers 22. As will be apparent, the nuts 2l may readily be tightened to hold the described assembly in position.

The embodiment of the invention illustrated herein includes a set of three separated collinear units of equal, selected resonant lengths mounted on each cross arm to form structures having the required rigidity to be self sustaining in space as shown when the cross-arms I3 and i4 are mounted on a mast in the desired positions, all being more fully described hereinafter. To mount the two sets of collinear units on their respective cross arm supports, each cross arm I3 (or I4) has an array of identical, parallel supports 23 projecting laterally therefrom. In this instance, ve such supports are preferably mounted on each cross arm in substantially equally spaced relation and extending in the same horizontal direction.' These supports may also take the form of hollow tubes of light metal, and may be of stillsmaller diameter than the cross arms I3 and I4. They are conveniently mounted in apertures drilled diametrically through the cross arms with an end of each support flared out at 26 to prevent its Withdrawal. Movement of the supports in the opposite direction may conveniently be prevented by deforming portions of the walls of the cross arms to form lips 2l extending into notches 28 in the supports.

- The center and two adjacent supports 23 on each cross arm all carry suitable spacing insulators 29 thereon for supporting adjacent ends of the -collinear units in spaced-apart relation, and

center thereof. The two outermost supports 23 on each cross arm both carry suitable bracing insulators 3l thereon for giving 'additional support to the end collinear units of each set.

The spacing insulators 29 may conveniently be rectangular in form with holes drilled therethrough at their ends to receive machine screws 32, to whi-ch the adjacent looped ends of collinear units are secured by nuts 33. Each spacing insulator 29 may be mounted on its support 23 by another machine screw 34, which may be threaded into a nut 33 jammed into the end of the support 23.

The bracing insulators 3| are preferably in the form of square blocks of sufficient thickness for holes 37 to be drilled edgewise therethrough to receive the end collinear units. Each bracing insulator may be mounted on its support 23 by means of a machine screw 38 threaded into a nut 39 jammed into the end of the support 23.

The two sets of collinear units respectively associated with the upper and lower cross arms I3 and I4 are identical, and a description of one is equally applicable to the other. Referring to either set, the center unit il is broken in the middle, as noted above, to provide two separated conductor parts alla and Mb having their adjacent ends connected to a spacing insulator 29, as described above. The outer units 42 and 43 are unbroken conductors that are collinear with the center unit and are physically and electrically spaced therefrom at opposite ends thereof by additional spacing insulators 29, as described above.

The physical lengths of the units 4I, 42, and 43 are empirically selected in accordance with well-known principles to be of substantially equal resonant lengths of 1/2 wave length each, or any whole multiple thereof, the wave length upon which their dimensions are based being a selected one in about the center of the range of wave lengths to which maximum response of the connected circuit is desired. Thus, the upper and lower sets of collinear units per se are conventional.

As will be apparent from the foregoing description of the manner in which each set of collinear units is mounted with respect to its cross arm, each cross arm is insulated from the collinear units carried thereby land serves both as a structural support and as a reflector therefor. This arrangement effects a considerable economy of material by eliminating the electrically nonfunctional cross arm usually disposed betweenV the collinear units and the reector.

In an effort to nd means for improving the gain and for broadening the band response of two vertically stacked sets of collinear units of the character described above` (each unit having an effective resonant length of one-half of the selected wave length in the high television band) I rst added a conventional, quarter wave, phase reversing stub between ea-ch two adjacent units of each set. With this arrangement, the two sets of collinear units were rotated about their longitudinal axes to dispose the stubs at various angles to the vertical and to dispose the stubs of one at various angles with respect tothe stubs of the other (no reflectors being employed). One such arrangement is diagrammatically illustrated in Fig. 10 where the stubs Su of the upper set hang downwardly in a vertical plane and the stubs S1 of the lower set project upwardly in the same plane. A conductor C1 was connected between the center units of the two sets on one side of the central break therein, and a parallel conductor Cz was connected between the center units of the epson-a1 therein. The terminal ends T1 and T2 ofLa tWoconductor radio frequency transmission line were connected to the mid-points of the conductors C1 andiCz. l

With the general arrangementshown ini'Fig. 10, the gain of the antenna over the entire high and low television bands reached its maximum at about 190 megacycles and dropped off4 sharply to less than half the maximum at 170 megacycles and to less than two-thirds the maximum `at `2-20 megacycles. In the low band, the gainreached a maximum of about 40% of the high band maximum at 65 megacycles and droppedoff sharply to about 50% of the low band `maximumvat() megacycles and to lessthan 50% of the low band maximum at 90 megacycles.

The characteristics of this antenna as regard the impedance match of the antenna to the line (standing wave ratio) corresponds closelyto the gain characteristics, as shouldbe expected. In the high band, this ratio was about 1.25 at about 190 megacycles, but rose sharply to about 4 at 220 megacycles and to about 4.7 at 170 megacycles. In the l-ow band, this ratio was a minimum of about.2.3 at about 65 megacycles and rosesharply 4to about 3.9 at 90 megacycles and to about 4.2 at 50 megacycles. Since the required'condition for high gain broad band perfarmancel is a standing wave `ratio near unity over the entire useful band, it is apparent that this antennashowed no particularly unusual broad band characteristics, though the gain at the optimum frequencies" was very good.

Rotation of the two sets of collinear units'to vary'the angles of the planes of the stubs to the vertical had essentially no effectonthe standing .Wave ratio or gain of th-e antenna over any part of the high and low bands. When the planes of the stubs were horizontal, the radiation pattern of the antenna ina horizontal plane, measured with horizontally polarized waves, exhibite'dslight lobes. at the 90 position, but this effect was small and Varied only slightly with frequency.

Thus, while `the two sets of vertically stacked collinear units with phase reversing stubs could be connected in parallel by conductors C1 and C2 to obtain greater gain, the combination was still responsive only to a very narrow `range offrequencies, regardless of theorientation of `.the`two sets. The addition of reflectors producedthe expected effects of further` increasing thegainand making thecombination more highly directional,A but nothing more.

After considerable experimentation, ,I finally' electrically connected the stubs of one set to the respectively aligned stubsof the other setas diagrammatically illustrated in Fig. l1. Upon testing the performance of this arrangement, startling broadbanding effects were obtained. The gain over the high television band reached substantially the same maximum as the arrangement of Fig. l at about 190 megacycles'but. it fell off slowly not `over 5% up to 220 megacycles `and down to 170 megacycles. In the low band, the gainreached a maximum at about 65 megacy-cles, which was about greater gain than `wasobtained in this band withrthe arrangement in Fig. 10, and the gain fell off slowly `only about up to90 megacycles and only about` 20% `down .to 50 megacycles. The standing wave ratio curves were similar to the gain curves `when plotted against frequency. ,In the .high band, thisra tio yvaried between `the optimum flgureof 1.25 at 190 megacycles to a maximum of only yabout 1.5 `at 6. 220 megacyclesandil at -lmegacycles Imthe low band, `the optimum ratio was .about :1.7.5:at 65 megacyclesrand rose only Gto about1'2.6 "at .90 megacycles and 2.1 at 50 -megacycles This` vremarkableuniformity of gain attthe high level indicated bythestanding waveratio over the.y entire high band, and the excellent characteristics in the low band withthesame antenna, vfarexcellthe perfermance `characteristics of f anyiantennalwith which I-amfamiliar. For aneasierfcomparison of the improvement -obtainedwith the antenna; of- Fg. 11 over the antennaofil'ig. 10, referencemay be made' tothe following tabulation of' the figures; given inthe foregoing discussion withapproximate intermediate valuesadded:

"Standing Wage "Gain, Ypercencof l Ratio Maxima Frequency (Megacycles) lI am unable to explain, by `any satisfactory analysis of the arrangement shown in'Fig. `11., why it has the outstanding performance characteristics described above. VCount-acting'thewstubs back-to-back, however, is obviously largely responsible for Asuch performance characteristics, which far exceed anythingachievedheretofore to the bestof my knowledge.

Upon translating this electricalarrangement into a physical form suitable for commercial `pro-- duction, Irst constructed each'parfof back-toback stubsSu and Si of three conductor elements C3, C4, and C5 (Fig. 11) so `thatthe assembled aerial resembled a ladder with the stub conductors C3 and C4 and the centerset ofinterconnecting conductors C1 and C2 forming the rungs and holding the two sets of collinear units in fixed, spaced, parallel relation. When preassembledon the cross arms i 3 and T4, thisstructure is` so bulky Vastomake packaging and shipping costs prohibitive. I If shipped disassembled, the assembly time ,required atthe point of installation is excessive compared .to other aerials of simpler construction, 'but inferior performance, which 'havebeen in wide commercial use.. To overcome these commercial objections to my` new aerial arrangement, I'have devised a collapsible physical embodiment of 'the electricalelements which can be compactly packaged for shipment and quickly extended andmounted at the point of installation.

VReferring again toFigs. 1 and '2 and `also 'to Figs..5 ,6, 8, and 9, collapsibility of the unitshown therein is achieved by constructing veach pair of back-to-back stubs 5(such as su and Siin Fig..1 1') of ve pivotally connected conductor elements instead of three conductor elements. Thus, .each upper stub includes a pair of, parallel, vertical conductors .46a and 41a, and each'lower stubincludes a pair` of identical, parallel, verticalconductors 4Gb and 41h; and a common, shortconductor `48is vpvotally connected at .one end .to both the .upper andloweraligned conductors 46a upper and' lower aligned conductors "41a and 41h'.

These pivotal connections may conveniently be made by formingloops in the ends of the conductors to be joined and simply inserting a machine screw through the loops, applying a nut loosely thereon, and mutilating the threads on the portion of the screw that projects beyond the nut to prevent its accidental removal.

The upper ends of the conductors 46a and 41a are also pivotally connected, respectively, to the adjacent ends of the associated upper collinear units 42 and 4 I or 43 and 4I, and to the intervening insulator 29, as shown in Figs. and 6. Similarly, the lower ends of the conductors 4Gb and 41h are pivotally connected, respectively, to the adjacent ends of the associated lower collinear units 42 and 4I, or 43 and 4I, and to the intervening insulator 23. The machine screws which may suitably be employed to form these pivotal connections, such as the screws 32, preferably have the verticalv conductors applied after the nuts 33 have been applied and tightened, and additional nuts 5I are then loosely applied. Again, the assembly may be held together against accidental removal of the nuts 5l from the machine screws by mutilating the threads of the portions of the screws that project beyond the nuts.

Similarly, the conductors C1 and Cz, to which the terminal ends T1 and T2 of the transmission line are connected in Fig. l1, are respectively replaced in Fig. 1 by an identical pair of vertically aligned conductors 52a and 52h and by another identical pair of vertically aligned conductors 53a and 53h. The upper ends of the conductors 52a and 53a are pivotally connected, respectively, to the adjacent ends of the sections dla and Mb, of the central collinear unit 4I. The lower ends of the conductors 52h and 53h are pivotally connected, respectively, to the adjacent ends of the sections 4Ia and Mb of the lower collinear unit 4|. These pivotal connections may be made in the same manner shown in Figs. 5 and 6.

The adjacent ends of the upper and lower conductors 52a and 52h are pivotally connect-ed to each other and to one end of a short insulator 54, as by a suitable machine screw and nut; and the adjacent ends of the upper and lower conductors 53a and 53h are similarly connected tothe opposite end of the short insulator 54. The terminal ends 56 and 51 of a two-conductor radio frequency transmission line, such as a conventional twin-lead line, are respectively connected to these pairs of upper and lower conductors, the connections conveniently being made by means of the same machine screws and nuts employed on the short insulator 54.

With this structural arrangement of the pairs of back-to-back stubs and the pairs of conductors to which the transmission line leads are attached, three parallel motion linkages are provided for connecting the upper set of collinear units to the lower set of collinear units, as diagrammatically illustrated in Fig. 9. The fully extended positions of the various elements of the structure are indicated in Fig. 9 in dot-dash lines, and the partially collapsed positions of the elements of the structure are shown in solid lines. The collapsing action is alsoillustrated, in part, by Fig. 8, showing the partially collapsed parallel motion linkage formed by the conductors 52, 52h, 53a and 53b to which the leads of the transmission lines are connected.

'I'his collapsible structure permits the entire aerial unit to be completely assembled in the factory with the machine screws and nuts forming the various pivotal connections loosely assembled. as described above. By moving the upper, relatively rigid frame of collinear units and cross arm I3 toward the lower frame of collinear units and cross arm I4, the completely assembled structure may be collapsed into a compact unit, little thicker in its vertical dimension than the combined vertical height of the two brackets employed for mounting the aerial unit on the mast I2. If it is desired to collapse the structure further to form a still flatter package, these brackets may be left olf the assembly at the factory and packaged loosely therewith.

When the collapsed unit is removed from a package or carton at the location where it is to be installed, the structure may readily be pulled out to its fully extended condition and the nuts and machine screws forming the pivotal connections may 4be quickly tightened by means of a screwdriver and suitable wrench or pliers. The resulting structure, when mounted on the mast I2 in the manner described above, is suniciently strong and rigid to withstand winds of gale force.

The antenna assembly of this invention is adapted to be duplicated, to the extent desired to obtain still further gain, by stacking one such assembly above another on the same mast and connecting them to the transmission line in parallel in a well-known manner.

While the features of the invention responsible for high gain, broad band performance have been illustrated as applied to sets of collinear units comprising three units each, they are applicable to arrangements having any desired larger number of collinear units per set. An odd plurality of collinear units per set is preferred, because of the natural impedance match of the antenna to the transmission line when the line is connected through transverse conductors to a center unit of each set at a central break therein. However, with suitable matching of the impedance of the antenna to that of the line, by adjusting in a well-known manner the impedance of the transverse conductors to which the line leads are attached, excellent characteristics can also be obtained with four, six, eight, etc. collinear units per set. With an even number of units per set, the line leads are, of course, connected to transverse conductors respectively joining adjacent ends of the center-most units in one set to adjacent ends of corresponding units in the other set.

The structural features of the invention which render the fully assembled aerial unit collapsible are obviously applicable to numerous other forms of aerials. Accordingly, the scope of the invention is to be construed as limited to aerials employing spaced sets of collinear units only as required by the terms of the appended claims.

For convenience, in this specification and in the appended claims, the terms antenna and antenna system have been employed to designate the entire energy receiving or transmitting apparatus that is normally connected to the antenna terminals of a transmitter or receiver, and the term aerial has been employed to designate only the energy radiating or intercepting members and their physical supporting structure, excluding the transmission line.

From the foregoing description of my invention, it will be appreciated that I have provided a high gain antenna system having remarkable broad band characteristics. It will also be appreciated that the system has been embodied in a physical form which may be preassembled in theractory, packaged, and shipped in acollapsed conditionand'quickly extended and made rigid atI the place of installation .for convenient mounting on a single, verticalFmast of` any desired type. i It will l also be. appreciated that these operational results. have been accomplished with vgreater than. usual economy of materials.

Having described my` invention, Il claim: 1. Anantennacomprising a pair ofrigid'elonlgatedreflector rods of vrelatively large diameter disposed in. transversely aligned parallel relationship, means on said reilectors forseparately securing them insuperposed horizontal positions to a vertical. mast, includingmeans for positively restraining said reectors against rotation about their respective longitudinal axes, each of said Areflectors carrying a series of conductor sup- `portingrods of relatively small diameter, each ,conductor supporting rods `carried by one reflector to form a cantilever assembly supported by its reector, each collinear conductor being supported. atpoints spaced along itsllength by at leasttwo. of said conductor supporting rods,

. asecond setoof at least three generally collinear conductors of relatively small diameter correspondingly mounted.` in longitudinally spaced `relationship on the opposite ends of the series of' conductor` supporting rodsii carried by the other' reflector to form. another'. cantilever' assembly supported by its reflector, and a plurality of vertically extending phasing units spaced along the lengths of said sets of collinear conductors and mechanically connecting each conductor of each collinear set to the corresponding conductor in the other collinear set for stabilizing the cantilever assemblies and maintaining the sets of collinear conductors in vertically spaced, generally parallel, relationship.

2. An antenna according to claim l in which each of said phasing units comprises a pair of spaced, transversely aligned, generally vertical, conductors extending between said sets of collinear conductors and a generally horizontal member mechanically connecting the mid-points of said generally vertical conductors and maintaining the transverse spacing thereof.

3. An antenna according to claim l in which each of said phasing units comprises an upper pair of spaced, transversely aligned, generally vertical, conductors and a lower pair of spaced, transversely aligned, generally vertical, conductors mechanically connected to said upper pair midway between said sets of collinear conductors, said upper and lower pairs of generally vertical conductors being hingedly connected together and to the upper and lower sets of collinear conductors, respectively, for pivotal movement about parallel horizontal axes to provide a parallel motion linkage permitting collapsing of the antenna structure.

4. An antenna according to claim 1 in which each of said phasing units comprises an upper pair of spaced, transversely aligned, generally vertical, conductors and a lower pair of spaced, transversely aligned, generally vertical, conductors mechanically connected to said upper pair midway between said sets of collinear conductors, said upper and lower pairs of generally vertical conductors being `hingedly connectedy together and to the upper and lower sets of collinear conductors, respectively, for pivotal movement about parallel horizontal axes to provide a parallel motion linkage permitting collapsing of the antenna structure, and means `for tightening at least one of sadhinged connections of each of saidphasing units to resist pivotal'movement and rigidify the `structure when said" reflectors are securedto a mast;

5. Anv antenna lcomprising `a pair of rigidelongated reflector rods of relatively large diameter disposed in transversely aligned parallelrelationship, means on said reflectors for separately securing them in superposed horizontal positions to a vertical mast, including means forpositively restraining said reflectors against rotation about their respective longitudinalaxes, each of said reflectors carrying a series of conductor "supporting rods of relatively small diameter, each of which has one end rigidly secured to its reilector, said conductor. supporting rods being carried. entirely by their reflector and extending horizontally therefrom in the same direction asparallel cantilevers, a rst set of 'at least three generally collinear conductors of relatively small diameter mounted in longitudinally spaced relationship on the opposite ends of the seriesof 'conductor supporting rods vcarried by one reflector to form a cantilever assembly supported by its reflector, each collinear conductor" being supported at points spaced along its lengthby at least two of said conductor supporting rods, a second setof at least three generally collinear conductors. of relatively small diameter correspondingly mounted in longitudinally spaced relationship` on the opposite ends of the series of conductorsupporting rods carried by the other reflector to form another cantilever assembly supported by its reflector, and a plurality of vertically extending members spaced along the length of said sets of collinear conductors and mechanically connecting each conductor of each collinear set with the corresponding conductor in the' other collinear set for stabilizing the cantilever assemblies and maintaining the sets of collinear conductors in vertically spaced parallel relationship.

6. An antenna according to claim 5 in which said vertically extending members include at least two spaced pairs of generally vertical conductors, the conductors of each pair mechanically connecting adjacent ends of two collinear conductors of one set to adjacent ends of two collinear conductors of the other set.

7. An antenna comprising a pair of rigid elongated metallic reectors disposed in transversely aligned parallel relationship, brackets on said reflectors for separately securing them in superposed horizontal positions to a vertical mast, each of said reflectors carrying a series of metallic conductor supporting rods, each of said rods having one end rigidly secured to its reiiector and extending horizontally therefrom in the same direction to form a series of parallel cantilevers, insulators on the opposite ends of said conductor supporting rods, a rst set of at least three generally collinear conductors mounted in longitudinally spaced relationship on said insulators on the series of rods carried by one reilector to form a cantilever assembly supported by its reflector, a second set of at least three generally collinear conductors respectively mounted in longitudinally spaced relationship of 1l said insulators on the series of rods carried by the other reector to form another cantilever assembly supported by its reflector, each of said sets of collinear conductors being provided with at least two spaced pairs of phasing conductors A and each pair of phasing conductors being respectively connected to adjacent ends of spaced collinear conductors of the same set for rotation about a horizontal axis, the pairs of phasing conductors of the two sets being of substantially the same length and symmetrically arranged and the pairs of phasing conductors of each set normally extending toward the respectively opposite pairs of phasing conductors of the other set, and each pair of phasing conductors of one set being hingedly connected to the opposite pair of phasing conductors of the other set midway between the two sets to provide a parallel motion connection permitting collapsing movement of the rigid assemblies of the collinear conductors and their respective reectors and supporting rods toward and away from each other.

8. An antenna according to claim 7 in which the hinged connections between opposite pairs of said phasing conductors include generally transverse elements connecting the phasing conductors of each pair with a fixed spacing at said hinged connections.

9. An antenna according to claim 7 in which said pairs of phasing conductors are respectively connected to adjacent ends of spaced collinear conductors for rotation about a horizontal axis normal to the plane defined by said reflectors, and opposite pairs of phasing conductors are hingedly connected for relative pivotal movement about axes normal to the plane defined by said reflectors.

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

UNITED STATES PATENTS Number Name Date 25,086 Berry Aug. 16, 1859 1,775,801 Alexanderson Sept. 16, 1930 1,779,437 Loughridge et al. Oct. 28, 1930 2,112,269 Carter Mar. 29, 1938 2,163,770 Von Radinger June 27, 1939 2,577,469 Kumpf Dec. 4, 1951 OTHER REFERENCES "JFD Super-Beam Television and FM Antennas," published by JF'D Mfg. Co. Inc., Copyright, 1948, single sheet advertising leaflet, Form No. 'FV-A (second side applied);

Channel Master Television and FM Antennas (3 Star Line), published by Channel Master Corp., February 17, 1949, page 2 of pamphlet applied; page heading: Hi-Gain."

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