US2897495A - Foldable antenna structures - Google Patents

Description

July 28, 1959 A. F. CARTHAY 2,897,495

FOLDABLE ANTENNA STRUCTURES Original Filed April 9. 1954 I 4 Sheets-Sheet 1 H. F CarZ/iay IN V EN TOR.

Mire-- M MI/Q July 28, 1959 A. F. CARTHAY FOLDABLE ANTENNA STRUCTURES Original Filed April 9.

4 Sheets-Sheet 3 INVENTOR.

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mam fig i A. F. CARTHAY FOLDABLE ANTENNA STRUCTURES Jul 28, 1959 4 Sheets-Sheet 4 Original Filed April 9. 1954 INVENTOR.

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v fiS'A'ITORNEYJ' FOLDABDE STRUCTURES- Alexander :F. Carthay, Kerhonkson, N .Y.,. assignor,- by

mesne assignments, sto Channel Master Patent Corp. Greensbor0, -N.C.,. acorpqrationsot North Carolina Original application April"9, 1954-, Serial Nol- 422,117.33 Divided. and this application :January;18, 219.55, Serial. No. 485,575

14 Claims. (Cl; 343=+803).""

The present invention concerns improvements: in :an

tennastructure,- and particularly in antennasrof the type disclosed and claimed in-copending app lication,rSerialrNo;-: 418,553, filed March 25, 1954, in thename of YuenTze.

Lo and'entitled -Wide Band Antenna-1? J Thepresent'apgaq plication-is a division of myco-pending applicationiSer': No; 422,173 ofthe-same title, filed April:9, 1954.

In the mounting of television-antennas, generally upon roof tops, installers must work: in precarious andadangen: ous positions.- It istherefore important-to provide .an-v tennas-which can readily be-assembled and handledduring erection, with a minimumof tools and manual opera! tions, soas'to minimize the dangers-of such installations.

In addition, from the view point of the manufacturer, it is important that the-various component parts be simply fabricated and assembledat the factory, to provide anantenna which can-be compactly and-simply packaged and'yet quickly unpacked and assembled at the installationspot,'-while still providing efiicient electrical operation'and rigidity in the mounted condition.

These and other advantages and objects of thepresent inventionwill be more readily understood from consideration' of the following description taken in conjunction with the appended drawings; in which Fig.11 is a perspective-assembly viewof one form of the present invention.

Fig. 2 is a fragmentary frontview of'thestructure of Fig; 1.

Fig- 3, is a fragmentary, bottom view of the structure n Fig. 7 is a perspective view of a two-bay arrangement of the structure of Fig. l.

The present invention is illustrated particularly as appliedto a tri-pole or triple dipole arrangement for wideband television reception, whose principles are describedin the forementioned Lo patentapplication, althoughin its broader aspects the present invention is not limited thereto. As disclosed in said Lo application, thetripole antenna has one long or low-banddipoleabove.and. below which are respective ones of a painof short or high? band dipoles, interconnected by-a transmission. line" harness having three transmission line sections coupled to a pair of common terminals, the antenna having also a verticalreflector screen spaced fromcthe dipole array. Fig. v1 is a perspective view of an embodiment; of the L0 tri-pole*- antenna incorporating structuralnfeatures according .to the present invention.

As shown in Fig. l, a long (low-band)..foldeddipole 2,897,495 Patented July 28, 1959 51 is mounted substantia-llydn a horizontal plane =above and-below which are the short thigh bandq tolded di poles 52 and 53-, equally spaced *theref-rom, and also v respective horizontal-planes The' flong a dipole '51 is spaced-closelyand parallebto thelshorbdipoles 52, 53 their electrical characteristics and interrelationship beingdescribed in said Lo application.

All of the-dipoles 51, '52, 753 are mounted on a vertical post 91 which in turn is--secured-'-to. a horizontal-cross arm -'54,which--is supported from a vertical mast .155'; usually mounted on the house orbuilding structurenl The 1 cross arm 54 alsosupports the-reflector screen 56, shown in this instance asa plurality-of parallel 'horizontal -rod 4 57 with a pairof joined ver tical-rods 58. This structure. is described morein detail below. Atransmission line gz harness :46 interconnects the dipolesi 5'1, :52,i:53- to ta terminal -block -from: which :thetdown-lead, .transmissionuu line extends to the-.receiven Thepstructural-features of thisfiantenna, whichaprovideir-s advantages in fabricationy-in structural strengthf'zand'zsta-ns bility, and in ease :of assembly, are shown: in. Figs;.:-:-2 As will be seen,z:the' antennastructure asaa .wholeiis made u collapsible andifoldablmrso that-it may-be readily; paclcdmi. for ship-mentand them in. a simple. manner; erected :witl'r :2 s a minimums-of effort and :the use: ofia minimuminum-ber a; of tools Thelong dipolezSI-ismadezof conductive tub:- it. ing,= :such .asaluminum tubingnanmasseen most: clearly in Fig-:3, maybe formed; ofa: singlejongrod 571having e its ends benttsandrfiattened'as;at= 7.2, intassociatiomlwith a pair'of shorter:rods;.73 each having a similar v.bentand flattened; end;:74i "securedsito a respective: :end 12 a as by 1 riveting :a-t '75. ,TheLother endsrof theshorten rods 7,3 31? fiattenedzas at. 76, and; are :rivetedor, otherwise: suitably fixed to:an 'insulatinghlock :17, suclnas of Bak1elite,:,;1\ Ii cartazor thelliken; coupling:harnessindicated generally. :at. 46.has, three :transrnission linezsectiombranchesa2;: one .branchr-79- having :its respective..terminalszzjoinedto thezflattened ends 76, oh therodsp73, ,as;by the samegrivetsr which-secure rrods 373 t0'1bl0ck:'77,. .Therother terminals;;;. of .this harnesszbranch179 are riveted. OI OthI?WlSeT,Se* cured: to. the terminals '8l ofaarterminal, :block;82 tonvhic it: are also joined 1 the other-harness 'rbl'flHChCS ;-83- ,an -1 84; leading .to the smaller.;dipoles:52.-.and 5 3;

The smaller dipoles. 52 and 53 are fonnedsimilarly to the long dipole 51, each ihavingwalonglunintermptedsides 86 and an interrupted'isideiparallel thereto-ihavingarms. 8'7 with flattened, endsn fijoined to a respective insulating block-89 and90.- Whereqdesired, each;ofthese--;fo1ded-- dipoles: 51; E52 and.: 53,- ;can bermade of. a single. .piece tubing bent into a flat elongated loop with one unint rupted side. and the :othereside interruptcdwat its eeutento form two adjacentendsmounted onterminal blocks such; 1; as 77, 89 and-90, as. shown for small dipole SZinFigiA or they may be madeiof separate rods joinedjiat; their endsrn as described: relative to .dipoleSl: and shown in Fig, '13..

For the purposeofrigidly mountingathecdipoleassems;- bly from the cross arm :54, a vertical supporting .post. 91 5 is provided .whichthasia bayonet socket-or-other suitable; clamp-92 at its centerextending perpendicularly. there from for the purpose of receiving the end of the cross 1 beam 54: As shownat Fig. 5, the socket-92 may be secured by rivets, bolts-welding or the like to the sup porting post 91; as at 93; andmay have the cross arm 54- secured" thereto as by; a screw or projections 94. For 1 assembly, with screw 94iloosened, cross arm 54 is inserted into the socket 92'with the screw shaft. registeringwith' slots of socket 92.: Theslots 100 have right angled branches..into..which,;screws94 seat... Then a. wing ,nut 94a'maybe.tightenedon: screw .94 to make ..,a rigid stmcra ture. It willbel-understood, that. while this is a. simple and;-:- convenient arrangement-for joining-the cross; bearn fi tm-l 3 to the supporting arm 91, other equivalent means may be utilized.

For purposes of ease of packing and shipment, and of assembly on the job, each of the dipoles 51, 52 and 53 is pivotally joined to the supporting post 91 so that this subassembly can be folded with post 91 essentially parallel to all three dipoles superposed on one another, and the assembly is adapted upon unfolding to be locked or clamped to the post 91 perpendicularly thereto. For this purpose, each of the short dipoles 52 and 53 has a clip 95 secured thereto as by a long rivet 96 passing diametrically through the supporting post 91 and through the tubing 86 forming the long side of the dipole, at its center. The clip 95 is formed of two sections 95a and 95b, each having a groove formed therein to receive the dipole tubing 86. Clip portion 95b is formed with an elongated flat portion 97, having a pointed detent 98 extending at right angles therefrom. When the short dipole 52 or 53 is rotated about the pivot axis formed by rivet 96, to a position of perpendicularity to the supporting post 91, the detent 98 slips into a hole 99 formed in the supporting post 91, and serves to retain the dipole in this perpendicular relationship to supporting post 91. 1t will be understood that the clip portion 97 has sufficient resilience to permit the detent 98 to spring into and be retained in the hole 99 for locking the dipole in place. Also held by the rivet 96 is a rigid wire support 101 having an eyelet at its opposite end which is riveted as at 102 to the center of the insulating block 89 which spaces the terminal ends 88 of the short dipoles 52 and 53. This wire 101 serves to maintain the end terminals 88 of the short dipoles 52, 53 in rigid relationship to the remaining structure.

As shown in Figs. 2 and 5, the long dipole 51 is similarly pivotally secured to the supporting post 91 by a long rivet 103 passing through post 91 and the tubing section 71 of the long dipole 51. A clip 105, having portions 105a and 10512, is also secured to the dipole tubing 71 by the rivet 103. Clip portions 105a and 1051) have grooves formed therein for receiving the dipole tubing 71. Clip portion 105b is extended in a flat plate 106 shown in Fig. 2, having a slot 107 for receiving a screw 108 passing through the supporting part 91 and having a wing nut or similar type clamping means 109 at the other end. In this way, the long dipole 51 may be swung at right angles to the supporting post 91 to a position where the screw 108 engages with the slot 107 of the clip portion 106. Tightening nut 109 then clamps the long dipole 51 in proper position rigidly.

A rigid wire support 111 is also secured by rivet 103 to tubing 71 and extends to the insulating block '77 joining the ends 76 of the long dipole 51 to maintain the dipole portions in proper electrical and mechanical relationship.

The ends of the branches 83 and Met the coupling harness are riveted respectively to the ends of the short dipoles 52, 53 by the same rivets which connect these dipole ends to their insulating blocks 89 and 90, and the other ends of these harness branches 83 and 84 are joined together to the terminals 81 of terminal block 82.

It will thus be seen that the collapsed assembly of dipoles 51, 52 and 53 and the supporting arm 91 is easily unfolded into operative position merely by rotating each of the short dipoles 90 until its detent 98 snaps into hole 99. Similarly, the long dipole is rotated 90 and clamped in position by the screw 108 and wing nut 109. The cross beam 54 is then inserted in the bayonet type socket 92 and secured by the screws 94. The terminal block 82 may then be secured to cross beam 54 by a screw passing through holes 80 and 121 in the block 82 and beam 54, respectively.

The cross beam 54 is preferably pivotally connected to the screen 56, as shown in Fig. 1, by being'pivotally secured to the center enlarged horizontal supporting bar 113 of the screen 56. Suitable clamping means, shown generally at 110, are provided so that the cross arm 54 4 may be locked into position perpendicularly to the plane of the reflector screen 56, as by way of a suitable wing nut and slot arrangement of the general character of plate 106 and screw 108 of Figs. 2 and 5. The screen 56 is also made collapsible by having all of its horizontal rods 57 pivotally secured to the vertical rods 58. At the points 114 at which the vertical rods 58 cross the center horizontal rod 113, locking means may be provided to maintain the screen locked in its proper open position. For example, a vertical groove may be formed in the outer surface near each end of the center rod 113' to accommodate one of the vertical rods 58 and the pivot at points 114 may be formed by wing nut and screw arrangements which rigidly clamp the vertical rods 58 to the horizontal rod 113 in only one position where the rods 53 seat in the said grooves so that these rods 58 and 113 are perpendicular to one another. The entire screen is then locked into proper relationship by this arrangement. The mast 55 may be clamped to the cross beam 54 by a conventional type of U-clamp 115, as shown in Fig. 1.

As an important aspect of the invention, it will be noted that each of the dipoles is conductively connected to the mast, at the center of the long uninterrupted conductor thereof, opposite its terminal block. At this point, because of symmetry considerations, the antenna is at fixed potential and is hence grounded, serving as a pr0- tection against lightning injury to the receiver.

In instances where it is important to provide a higher gain, the invention may be utilized in a stacked array having multiple bays, one above the other. Fig. 7 illustrates a two-bay arrangement formed by two units of the type described above. Each of the dipole assemblies 134 is described above, each being secured to a respective cross beam 54, which in turn is clamped in the manner already described to its respective reflector screen 56. For the purpose of joining the two reflector screens into a single screen, the ends of vertical rods 58 are flattened and apertured, so that the two aligned vertical rods 58 can be bolted together as at 141. Aligned ridges and grooves may be formed in these ends to maintain their alignment seated on one another.

The mast 55 is then clamped at 115, to each cross beam 54. A further coupling harness is provided, having a terminal block 136 from which respective transmission line branches 137 of equal length proceed to the respective terminal blocks 82 of the individual bays 134, secured to the cross beams 54 as described above. A further terminal block 138 is mounted on mast 55 between the cross beams 54, and a line section 139 extends from block 138 to block 136. The line sections 137 and 139 are preferably formed by rigid rods, the sections 137 serving properly to space the two dipole assemblies, and section 139 holding sections 137 rigidly in place. The down lead transmission line 23 is then secured to the terminals on block 138.

In a similar manner a four-bay arrangement may be provided, by connecting down lead 23 to the center of a line section connecting two terminal blocks 138.

It will thus be seen that the present invention provides a simple and eflicient wide-band antenna arrangement, easy to fabricate and assemble, and effective over the entire VHF range of broadcast television.

It is to be understood that the above description is illustrative only, since equivalent structural features may be utilized where desired, the present invention being defined by the appended claims.

What is claimed is:

I. An antenna comprising a dipole of the folded type formed by a narrow elongated planar loop of rigid conductive material having a long uninterrupted side and a parallel interrupted side having a gap substantially at the center thereof, said sides being joined at their ends, an insulating terminal block secured to the ends of said interrupted side on either side of said gap, a conductive supporting post for said dipole, means pivotally securing said uninterrupted side to said supporting post at the center of said latter side and in conductive relation thereto, with the axis of said pivot in the plane of said loop, and a rigid strut extending from the center of said terminal block to the center of said uninterrupted side for rigidly maintaining said two dipole sides in substantially parallel relationship.

2. An antenna as in claim 1, further comprising means for clamping said post perpendicular to the plane of said dipole loop.

3. An antenna as in claim 2, wherein said clamping means comprises a bolt passing through said post and spaced from said pivot axis, and a plate fixed to said dipole and having a slot engaging said bolt when said loop plane is perpendicular to said post.

4. An antenna as in claim 1, further including a pair of shorter dipoles, each of the folded type formed by a narrow elongated planar loop of rigid conductive material having a long uninterrupted side and a parallel interrupted side having a gap substantially at the center thereof, said sides being joined at their ends, means pivotally mounting each of said uninterrupted sides on said post on respectively opposite sides of said first dipole and with the pivot axis of each of said short dipoles in the plane of its loop, an insulating terminal block connected to the ends of said interrupted sides of each of said short dipoles and extending across the gap thereof, and a pair of further rigid struts each connected at one end to one of said latter pivotal mounting means and at the other end to a respective block for maintaining the sides of said short dipoles in spaced parallel relation, the uninterrupted conductors of each of said short and long dipoles being conductively connected to said post at the centers thereof.

5. An antenna as in claim 4, further comprising a cross beam secured to said post perpendicularly thereto, and a mast secured to said cross beam perpendicularly thereto for mounting said three dipoles in a vertical plane with each dipole in a respective horizontal plane.

6. An antenna as in claim 5, further including a screen reflector mounted on said cross beam at the end opposite said post and parallel to the plane of said dipole arrangement.

7. A collapsible antenna arrangement comprising a post adapted to be supported in a vertical position and a plurality of folded dipoles pivotally secured to said post at spaced positions therealong, each of said dipoles being formed as an elongated planar loop of conductive material having an uninterrupted side and a side parallel thereto interrupted by a gap at its center, and an insulating block straddling said gap and connected to the adjacent ends of said interrupted side, each of said dipoles being pivotally and conductively secured to said post at the center of its uninterrupted side.

8. An antenna as in claim 6, further including clamping means for maintaining said dipoles in perpendicular relationship to said post.

9. In an antenna arrangement, a supporting post, an

antenna element having a conductive rod as a portion thereof, a pin extending diametrically through said post and said rod for pivotally securing them together, a resilient plate secured to said conductive rod for joint roration therewith, said plate having a detent tip bent at right angles to said plate, said post having a recess adapted in one position of said rod to receive said detent, said plate being resilient to permit said detent to enter into said recess and for retaining said detent in said recess to clamp said antenna in a predetermined position with respect to said post.

10. An antenna arrangement as in claim 9, wherein said plate has a grooved portion conforming to and in contact with said rod, said pin constituting a rivet passing also through said plate and securing said plate to said rod.

11. A collapsible antenna structure comprising a cross beam adapted to be secured to a vertical mast, a post removably secured to said cross beam at one end and perpendicularly thereof to be mounted in a vertical position, three dipoles pivotally secured to said post at spaced positions therealong, and means for clamping said dipoles to said post perpendicularly thereof to form a vertically arranged horizontal dipole array.

12. A collapsible antenna structure as in claim 11 wherein at least one of said clamping means comprises a resilient arm fastened to and extending substantially at right angles to the axis of a dipole, a recess in said post, and a projection on said arm extending toward said post and adapted to snap into engagement with said recess when said dipole is turned to a right angle with respect to said post.

13. An antenna as claimed in claim 8 wherein at least one of said clamping means comprises a resilient arm fastened to and extending substantially at right angles to the axis of a dipole, a recess in said post, and a projection on said arm extending toward said post and adapted to snap into engagement with said recess when said dipole is turned to a right angle with respect to said post.

14. In an antenna arrangement a supporting post, an antenna element having a conductive rod as a portion thereof, means for pivotally attaching said conductive rod to said post, a resilient arm fastened to and extending substantially at right angles to the axis of rotation of said dipole, a recess in said post and a projection on said arm extending toward said post and adapted to snap into engagement with said recess when said dipole is turned to a predetermined angle with respect to said post.

References Cited in the file of this patent UNITED STATES PATENTS 1,468,810 Hines Sept. 25, 1923 2,492,529 Kaplan Dec. 27, 1949 2,691,730 Lo Oct. 12, 1954 2,699,348 Fulop Jan. 11, 1955

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