US3725945A

US3725945A - Geared folding antenna

Info

Publication number: US3725945A
Application number: US00228637A
Authority: US
Inventors: L Lockwood
Original assignee: ANTENNACRAFT CO
Current assignee: ANTENNACRAFT CO
Priority date: 1972-02-23
Filing date: 1972-02-23
Publication date: 1973-04-03
Anticipated expiration: 1990-04-03

Abstract

A folding antenna is disclosed comprising a first elongated boom, an antenna element and a means pivotably securing the antenna element to the first boom for movement between retracted and extended positions. A first gear is drivingly coupled to the proximal end of the antenna element and a means for rotating the first gear is longitudinally, slidably coupled to the first boom. The antenna further includes a means for electrically connecting a transmission line to the antenna element and a means for clamping the antenna to a mast.

Description

United States Patent 1191 Lockwood [1 11 3,725,945 51 Apr. 3, 1973 [54] GEARED FOLDING ANTENNA [75] Inventor: Lynn L. Lockwood, Burlington,

Iowa

[73] Assignee: Antennacraft Company, Burlington,

Iowa

22 Filed: Feb. 23, 1972 21 Appli No.: 228,637

52 o.s.c| ..343/882, 343/882 51 1111.c|....; ..H0lq3/02 [58] Field of Search..-....343/763, 766, 805, 823, 839,

[56] 1 References Cited UNITED sTATEs PATENTS 2,476,469 7/1949 Walker .1.- ..343/823 3,665,477 5/1972 Budrow et al. ..343/882 Primary Examiner-431i Lieberman Attorney Harold B. Hood et all.

57] ABSTRACT A folding antenna is disclosed comprising a first elongated boom, an antenna element and a means pivotably securing the antenna element to the first boom for movement between retracted and extended positions. A first gear is drivingly coupled to the proximal end of the antenna element and a means for rotating the first gear is longitudinally, slidably coupled to the first boom. The antenna further includes a means for electrically connecting a transmission line to the antenna element and a means for clamping the antenna to a mast.

10 Claims, 3 Drawing Figures PATENTEDAPM ms 3.725945 SHEET 1 BF 2 FIG! PATENTEUAPRIS 197s sum 2 0F 2 FIGZ FICLS.

GEARED FOLDING ANTENNA BACKGROUND OF THE INVENTION 1 Field of the Invention The present invention relates to folding antenna structures and more particularly to a folding antenna which utilizes a plurality of gears in the folding mechanism.

2. DESCRIPTION OF THE PRIOR ART Antennas of the type used in reception of VHF television signals are relatively large, awkward to handle structures. Typically, these antennas are fabricated and shipped to their use site in a collapsed condition and are provided with appropriate means whereby each of the elements of the antenna array can be individually extended at the use site. However, once the elements have been extended, they cannot again be retracted or a considerable amount of. manipulation must be expended to do so.

Further, the expanding use of mobile homes, trailers and the like, as well as the generally increasing mobility of our society, render it desirable to have an antenna structure which can be easily extended and collapsed for transport.

It is therefore an object of the invention to provide a fold-ing antenna structure which is easily moved between retracted and extended positions.

It is another object of the invention to provide a folding antenna structure in which extension and retraction of the antenna elements can be performed in a single manipulation.

It is still another object of the invention to provide a fold-ing antenna structure utilizing molded components in the folding mechanism.

It is yet another object of the invention to provide a folding antenna structure which is simple in construction and economical to produce.

BRIEF DESCRIPTION OF THE DRAWINGS The above-mentioned and other features and objects of this invention and the manner of attaining them will become more apparent and the invention itself will be best understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a perspective view of a folding antenna in accordance with the invention;

FIG. 2 is an enlarged, fragmentary perspective view showing details of the boom coupling means; and

FIG. 3 is an enlarged, fragmentary perspective view showing details of the folding mechanism of the anten- DESCRIPTION OF THE PREFERRED EMBODIMENT adapted to engage the walls of first boom 12 thereby to position the hinge blocks 20, and a pair of outwardly extending

wing portions

26 and 28.

A hole 30 is provided through each

wing portion

26, 28 of each hinge block 20 and an elongated, threaded fastener 32 is received therethrough. A plurality of dipoles or antenna elements 34 made from elongated, tubular material are pivotably received on threaded fasteners 32 in a one to one relationship. Also rotatably received on each threaded fastener 32 is a cylindrical spur gear 36 each of which is provided with a notch 38. Antenna elements 34 each have their proximal end 40 received in the notch 38 of the respective one of the spur gears 36 whereby spur gears 36 are drivingly engaged therewith. Threaded fasteners 32 are secured in position with suitable nuts 42 and extend upwardly from wing portions 26 a sufficient distance whereby their distal ends 44 are disposed above the top surface 46 of first boom 12. While six pairs of antenna elements 34 are shown, it will be apparent that any suitable number and array of elongated elements could be used without departing from the scope of the invention.

A plurality of electrical connecting links 50, made from relatively stiff wire and having the ends thereof formed into eyelets which are received on the ends 44 of threaded fasteners 32, are secured with a pair of

lock nuts

52, 54, each electrical connecting link extending between a predetermined one of the threaded fasteners 32 and the next longitudinally adjacent but laterally opposite ones of threaded fasteners 32. Electrical connecting links 50 thus provide a means for electrically connecting together eachof the antenna elements 34. A selected pair of

lock nuts

52, 54 adjacent the center of the first boom 12 also serve as a means for electrically connecting a suitable transmission line 56 to electrical connecting links 50 and thereby to antenna elements 34.

To provide a means for rotating gears 36, there is provided a second elongated mast which is longitudinally, slidably coupled to first mast 12 by means of a plurality of collars 72. As best seen in FIG. 2, collars 72 each include alower plate 74 which is fixedly secured to second boom 70 by means of a recessed, threaded fastener 76. A notched, upper member 78 is secured to lower plate 74 with a pair of threaded fasteners as at 80. Upper and

lower members

78, 74, define therethrough an opening 82 complementary to the cross-section of the first boom 12 and the latter is slidably received therethrough as shown in FIG. 1.

Fixedly secured to second boom 70 in registry with each of the cylindrical gears 36 and meshed therewith are a corresponding plurality of rack gears 84. Each of rack gears 84 is so positioned that a similar portion of each of them is engaged with the respective cylindrical gear 36. It can thus be observed that when second boom 70 is moved longitudinally as indicated by arrow 86, rack gears 84 will drivingly rotate cylindrical gears 36 thereby causing antenna elements 34 to move between a retracted position in which they are disposed essentially parallel to first and

second booms

12, 70, and an extended position in which they extend laterally outwardly therefrom.

To provide a means for securing the antenna 10 to a suitable antenna'mas't there is provided a suitable U- bolt assembly 92 which includes a bracket 94 which engages first boom 12 and a U-bolt 96 which extends through suitable holes 98 in first boom 12 and is secured with a pair of nuts (not shown) in conventional manner.

There is also provided a second U-bolt assembly 100 which includes a bracket 102 and U-bolt 104. As with U-bolt assembly 92, bracket 102 of U-bolt assembly 100 engages second boom 70 and U-bolt 104 extends through holes 106 in second boom 70 and is secured with nuts (not shown). It can now be observed that holes 106 in second boom 70 are positioned such that U-bolt assembly 100 is disposed in vertical registry with U-bolt assembly 92 when second boom 70 is moved into position to extend antenna elements 34. Thus, when mast 90 is clampingly engaged by both U-bolt assemblies 92, 100, the latter positively lock the first boom 12 and second boom 70 against relative, longitudinal movement.

Further, when it is desired to collapse the antenna, U-bolt assemblies 92, 100, are disengaged from mast 90 and second boom 70 is moved longitudinally to the right (as viewed in FIG. 1), causing antenna elements 34 to swing inwardly as indicated by arrows 110 whereby the antenna can be easily transported to a new use site.

Preferably, both the cylindrical gears 36 and the rack gears 84 are of molded plastic. Similarly, collars 72 are made of a molded plastic material.

As shown in FIG. 1 only, first boom 12 may further be provided with a plurality of additional pairs of

holes

112, 114, each of the pairs of

holes

112, 114 being adapted to receive U-bolt 96 therethrough. Correspondingly, if U-bolt assembly 92 is secured to first boom 12 with U-bolt 96 extending through a selected one of the pairs of

holes

112 or 114, then U-bolt assemblies 92 and 100 will be in vertical registry for different relative longitudinal positions of first boom 12 and second boom 70. Accordingly, U-bolt assemblies 92 and 100 will be in registry for different positions of antenna elements 34 which positions will correspond to less than the fully extended positions of the antenna I elements 34.

It will further be apparent that the degree of extension of the antenna elements 34 will change the effective length of the dipoles, i.e., their length relative to the wave length of the received signals. Thus, if U-bolt assembly 92 is positioned in different ones of the pairs of

holes

112, or 114, and first boom 12 and second boom 70 are moved until the first and

second U-bolt assemblies

92, 100 are registry, and then secured to the mast which is then passed through the two

U-bolt assemblies

92, 100, there is provided a convenient means for varying the effective dipole length of the antenna elements 34 and thereby to tune the antenna assembly for optimum reception of a different, selected frequency such as, for example, a preferred or a weak channel.

Further, because the folding mechanism utilizes simple, molded components, these components can be manufactured and the antenna 10 produced at a minimum cost. The antenna elements are simply and easily moved from a retracted to an extended position and vice versa with a single manipulation and this movement can be repeated as often as required thereby rendering the antenna 10 well suited for use in installations wherein it must be periodically moved.

In a working model of the present invention, the following dimensions were used:

cylindrical gear 36, 1.25 in. diam., 13 teeth rack gears 84, 2.75 in. long, 9 teeth booms 12, 70, 1 inch square.

While there have been described above the principles of this invention in connection with specific apparatus, it is to be clearly understood that'this description is made only by way of example and not as a limitation to the scope of the invention.

What is claimed is:

1. For use in a folding antenna, a first elongated boom, an antenna element, means for pivotably securing said element to said first boom for movement between retracted and extended positions, a first gear drivingly coupled to the proximal end of said element, means longitudinally slidably coupled to said first boom for rotating said first gear and thereby moving said element between said retracted and extended positions, said rotating means including a rack gear meshed with said first gear, means for electrically connecting a transmission line to said element, and means for clamping said antenna to a mast.

2. The antenna device of claim 1 wherein said rotating means further includes a second elongated boom disposed in parallel, spaced-apart relationship to said first boom and means slidably coupling said second boom to said first boom.

3. The antenna device of claim 2 wherein said coupling means includes a plurality'of collars fixedly dielectric material and a hinge pin extending through said first gear and said hinge block.

5. The antenna device of claim 1 wherein said first gear and said rack gear are made of a moldable plastic material.

6. The antenna device of claim 5 wherein said first gear and said rack gear are made of a dielectric, plastic material.

7. The antenna device of claim 5 wherein there are a plurality of pairs of said antenna elements, and a plurality of said hinge blocks, there being one pair of elements pivotably secured to each hinge, block, the elements of each of said pairs extending outwardly from said first boom in mutually opposite directions when said elements are in their extended positions.

8. The antenna device of claim 7 wherein each of said elements is an electrical dipole, and further comprising a plurality of electrical connecting links for connecting said elements to said transmission line connecting means.

9. The antenna device of claim 1 wherein said first gear is a spur gear.

10. The antenna device of claim 2 wherein said clamping means includes a first U-bolt assembly secured to said first boom and a second U-bolt assembly secured to said second boom, said first and second U-bolt' assemblies being disposed in registry when said antenna elements are in their extended position, whereby said first and second booms are secured against relative movement when a mast is clampingly received through said first and second U-bolt assemblies.

Claims

3. The antenna device of claim 2 wherein said coupling means includes a plurality oF collars fixedly secured to one of said booms, each of said collars having an opening therethrough adapted to slidably receive the other of said booms.

4. The antenna device of claim 3 wherein said antenna element securing means includes a hinge block of dielectric material and a hinge pin extending through said first gear and said hinge block.

7. The antenna device of claim 5 wherein there are a plurality of pairs of said antenna elements, and a plurality of said hinge blocks, there being one pair of elements pivotably secured to each hinge block, the elements of each of said pairs extending outwardly from said first boom in mutually opposite directions when said elements are in their extended positions.

9. The antenna device of claim 1 wherein said first gear is a spur gear.

10. The antenna device of claim 2 wherein said clamping means includes a first U-bolt assembly secured to said first boom and a second U-bolt assembly secured to said second boom, said first and second U-bolt assemblies being disposed in registry when said antenna elements are in their extended position, whereby said first and second booms are secured against relative movement when a mast is clampingly received through said first and second U-bolt assemblies.