[1]United States Patent Office 31284 ' 972 3,284,972 PORTABLE TOWER WilIiam L. Werner, Sunnyvale, Calif., assignor to Granger Associates, Palo Alto, Calif., a corporation of California Ffled May 15, 1964, Ser. No. 367,850 8 Claims. (Cl. 52-118) This invention relates generally to antenna towers, and the invention has reference, morepartioularly, to a novel, easily portable and easily ins-talled highfrequency m-ultiple section @antenna tower. Heretofore, towers have been erected i@n sections ;and guy lines used at certain iiatervals along the tower ibeight to brace the tower -from the ground. The erection of such towers as bereto@fore constr-ucted has always been a timeconsu,min,g,and costlydperation, us@tially requiring scaffold structures and hoistin,- equipment -requiring the, crew to work at times well above the ,-round @with the -attendant dan,ger of aceidents. T,he pricipal object of the -present inveiition is to provide a novel, easily and quickly erected antenna tower comprisin,g upiper and lower tower halves, each tower half consistir@g o-f a - n-umber of @telesecyping tower sections, whereby the sections comprisin- eaoh tower half can be shipped, w-ith, its sections, completely telescoped one wit-hin the other, making an easily portalble structure, the tawer sections bein.- preferably rnade of light-wei,-ht material such as aluminflirn, and fa@bricated so as to have a maxisnum strength while employing a minimum of m,aterial. A feature o-f the novel tower of the -present invention lies in the fact that it can be erected by three to five men without gettin.- off the ground in less than one hour, and without the use of towers or other expensive equipment, the said erected tower possessing unusually high reliability and resistance t<) wind loadin,@ with a minimum of guy lines and a structural load cap,acity,aptproximating that of -an expensive fixed toWeT. Anot@her feature @of the present invention is toprovide a novel tower @of the above character which employs section joints that are made ri,-id by the use of push-button operated quick release lock-pins applied at ground level w-here the assernbly can bereadily checked before elevating tihe tower. Still another feat-ure of the invention is to provide asimplified, rug,-ed tower employing a minimum of gay ,lines, a seventy-four fo-ot, eiqht section tower employing but two levels of guy lines, for example, one set at ,midsection of the tower and another @at the top of the tower, -,vhereasheretofore, most sectional towers required guys at each se,etion joint because of the laclc of sufficient rigidity at joints!and lack of structural ri,,-idity or moment o@ inertia of the sectional cross-sections used. Still another @feature of the novel tower of the present invention is the use of tower sections of triangular crosssection, providing a thre,e-legged stpucture and a threepoint support on the tower base plate, to,@ether with novel, extremely rig-id le.- -cross,bracing and a doublehinge connection between the lower :and u-pper tower halves, which a small crew of men can use to jackknife the tower halves up, utilizing the top half of the tower as a gin or iprop to erect the lower tower half, the upper half of tihe tower @being erected by use of a novel yoke and to-,@gle structure and erection line. Thesc, and @otherfea-tures -and advanta-gesof the ptesent invention wil-I be more apparent after a perusal of thefollowin.- specification taken 1-n connection with the accompanying drawin@gs wherein: FIG. I is aperspdctive view illustrating a novel tower of this invention with a log-periodic, horizontally polar,=d, Patented Nov. 15, 1966 2 high-frequency antenna supported therefrom iby the use of catenaries" . FIG. 2 is a view in side elevation,of the erected tower showing certain positions of the tower during erection in dot-dash lines; FIG. 3 is a side view of apa-ekage com-prising the telescoped lower half sections of the tower; FIG. 4 is an enlarged fragmentary view looking in the direction of the arrows on line 4-4 of FIG. 3; 10 FIG. 5 is ra composite fragmentary view showinig the @manner of ri@,-idly connecting the tower sections; FIG. 6 is an enlar,,-ed view of the tower proper with parts broken away and showing details of construction; FIG. 7 is a sectional view taken along dine 7-7 of 15 FIG. 6; FIG. 8 is a -diagraminati@c view of a tower section unfolded to illustrate the pattern of cross-bracing used, and FIGS. 8A and 8B illustrate schematically ordinary types of cross-bracing in unfolded or developed form; 20 Similar characters of reference are useld in the above figures to designate corresponding parts. In FIG. 1, the novel portable tower is ill-iistrated in schematic form, erected and shown supiporting a highfrequency logperiodic horizontally polarized antenna com25 prising a series of porgressively spaced and centrally fed dipoles 2 supported by a catenary feed line cable 3 leading from the top of tower I to t-he apex 4 attached to the ground, the antenna being broad band -and radi,ating in the direction of the @apex 4 from the tower. Side cate3o naries 5 and 5' are t@ie@d by TOpes 6' to the lower ends of the d,;poles 2. Two sets of guy lines 6 and 7 are connected - resipectively to the top of the tower and to the central height of the tower tb maintain the same in fixed vertical iposition inuse. The tower illustrated is seventy35 five feet in hei,-ht although tallero@r shorter towers may be built incorpotat-ing the novel features of this invention. In FIG. 2, the to@ver is shown b@uilt up <)f a lower ha-If consisting of telescopic sections 8, 9, 10 and 11 progressive,ly increasing in width from the ,-r-ound up, and an 40 upper half consisting of telescopic section 12, 13, 14 and 15 pro,-ressively decreasing in width from the midpoint o,f the tower upwardly. Thus, the width and hence the resistance of the tower sections to bending increases progressively from the bottom and top of the tower towards 45 its central POTtion where -the greatest bending stresses occur in use. The four lower half tower sections 8, 9 10 and 11 are constructed so that -they can be nested o@ teles&oped together as shown in FIG. 3 when shipping the same, thus 50 making a very,compact package. These sections aTe of triangular sbape iand each consists of three tubes or rails arranged as a tripod cross-braced by a novel, light-weight cross-bracing 22. He,retofore, triangulair truss towers have been generally cross@braced by the Warren, or "W" type 55 bracin - or by the standard "Z" btacin.- such as shown in develped oT unfolded form in FIGS. 8A and 8B respectively. While the "W" type bracing oif FIG. 8A requires :about 10% less length,of cross-bracing for an equal -face width and bay 'height than the standard "Z" bracin,-, a dis60 advantage of t;his "W" type is that the internal volume of the structure is not enclosed by stract-ural meinbers fo-rining imaginary tetrahedrons; i.e., the simplest solid structures bounded by four triangles or six ed.-e members. The tetrahedral,design im@proves the structural rigidity and espe65 cially torsional rigidity, A further disadvantage of the "W" bracing is that the vertical rails of a tower using the sa-me are never supported @lateraliy in two pl:anes at one pointas -at points 16 andl6'inFIG.8A Ontheotherhandthe"Z"bra@cingnot 70 only requires considerably more metal -andhence is more expp-nsive than the "W" bracing, but the ;diagonal of the "Z" bracin.- is relatively long, and, since column load ca-
[2]3 pability varies inversely with the square of the length of the column a member of lower section modulus,and crosssectional,@@eas can beused when employing "W" bracing for equal -end 1.0ading capability. Critical column load for slender columns is given by E-uler's formula, i.e., 7r2El P@= L2 where: Pc=critical load in lbs. I=,moment of inertia E=modulus of elasticity L=Iength of column The present tower uses a novel type of cross-bracing 22 for a triangular truss tower as illustrated in FIG. 8 in which the advantages of both the "W" and "Z" bracing is obtained withou-t their disadvantages. The bracing of FIG. 7 is obtained by joining the two tubes or rails of a tower section face with bracin.- that is affixed to the rails in a single bay at one-third and two-thirds height poin@ts of the bay instead of the one-half bay point, as in the "W" bracing and the top and bottom of the bay as in th6 "Z" bracing. This novel bracing uses considerably less material length than the "Z" bracing, and the brace member length is also considerably less than the diagonal brace of the "Z" type. In addition, the bracing 22 used in the tower of this invention forms ima.,-inary tetrahedrals of all the enclosed volume Df the tower and supports the tower rails in two planes at each poin,t of support as with the "Z" bracing, thus forming an exceedingly rugged structure for the weight of metal used. As particularly shown in FIG. 4, the upper ends of -the tubular rails of lower half tower sections 9, 10, and ,11 are formed with inwardly projecting lugs or nesting brackets 17, 18 and 19 of U-shaped cross-section for receiving th-- rail and portions of -the next inner section. Thus, nesting bracket.19 of uppermost lower half tower section 11 receives the rails of section 10. In -use, the sections are pulled outwardly from their nested positions shown in FIG. 3 and the sections clamped together while lying on the ground through the use of push-button operated quick release lock-pins 20 carried by plates 21 fixed to the nesting brackets 17, 18 and 19, when shipped. Tbus, as shown in detail in FIG. 5, each of the nesting brackets has two apertures which when aligned with similar apertures in the end portion of the cooperating section rails, will receive a quick release lock-pin 20, care being taken to push the button in the middle of the handle of the lock-pin, push the pin all the way through the holes in'the nesting bracket and enclosed ,section rail such as 10, and then release the button, locking the pin 20 in place, and retaining the sections in rigid extended alignment. While the lower half tower is shown as composed of four sections, actually a lesser or greater number of sec-tions may be used. These sections are preferably made up of aluminum tubing or aluminum alloy tubing so .as to be light in weight, and yet very strong, whereby the sections can be nested and carried from place to place when desired, the quick release pins 20 enablidg the rapid assembly of the tower sections when erected, as well as rapid disconnecting and nes@ting when moving the tower. The four -upper tower sections 12, 13, 14, and 15 are ,likewise adapted to be shipped nested or telescoped and can Teadily be extended on the site of erection. As particularly illustrated in FIG. 6, the tower is .provided with a base plate 23, preferably of triangular shape. This plate 23 can be placed <)ver a tower locatin ing marking rod 24 when ' itially set up, and is provided with triangularly disposed hin@ge brackets 25. Tc) assemble the tower, holes provided in the iower ends of two of the tower legs of the small section 8 are aligned with corresponding holes in two of the hinge brackets 25 a@nd hingedly connected by pins- 20, as shown' in dot3,284,972 4 dash lines of FIG. 6, while the extended and locked together tower sections 8, 9, 10 and 11 lie upon the -round and are turned about marking rod 24 while tuming plate 23 until the extended lower tower half points in the desired direction -of antenna Tadiation of the t-ower, i.:e., in the direction of apex 4. The base plate 23 may now be anchored by driving in three anchor stakes 27. Two of the legs of large section 11 corresponding to the two legs of section 8 hinged to brackets 25 of base 10 plate 23 are provided at their upper ends with hinge brackets 26 adapted to receive corresponding mating brackets 26' provided on the lower end portions of two of the legs of upper large tower section 12. The upper tower half may be laid on the ground in line with its 15 lower tower half, then extended and its sections loeted together with lock pins 20 as in the -case @of the lower tower half sections. The cooperating hinge brackets 26 and 26' are adapted to mate and be connected by quick release lock pins 2o 20'. Before inserting the pins 20', however, an A-frame type of erection boom 28 is positioned so that its legs straddle segtion 11, the ends of the legs having holes to be aligned with the holes in brackets 26 and 26', as shown in FIGS. 6 and 7, wherever the pins 20' are in25 serted. This boom 28 has a shorter auxiliary b-oom 29 also of A-frame design connected thereto as by pivots 33, and the outer end of the auxiliary booin 29 is provided with a V-groove 30 for supp-orting an erection cable 38 as will further appear. The outer end portion 30 of this auxiliary boom 29 is connected by cable 31 to th6 top or outer end of the erection boom 28 and this outer end of boom 28 is also connected by cable 34 to the top of upper half tower section 13. A rigid boom stop or rod 36 is connected to erection boom 28 and 35 to upper half section 12 to position the erection boom with respect to the upper tower half. A short cable 37 is adapted to connect the middle of the auxiliary boom to the top rail of the lower half tower section 11 to limit the n-iovement @of the auxiliary boom. 40 Assuming the tower is lying on the ground, as shown in dot-dash lines in FIG. 2, and that it is now desired to raise the same, the erection cable 38 is snapped by a snap fastener 39 to the end of the main erection boom 28, and the cable is laid along the lower tower half 45 so as to fall into the V-groove 30 of the auxiliary boom as the tower is raised. Bracket 46 carrying guy lines 7 (see FIG. 6) are connected by quick release pins 20 to the upper end portions of the rails of lower half section 11. Also, guy lines 6 are connected by quick release 50 20 to the upper bracket 49 at the peak of the upper tower section 15. The catenary feed line 3 supporting the antenna dipoles 2 is attached to a swivel pin 40 inserted into the upper bracket 49. Since the tower is of strong, light-weight constr-uction, it can be raised 55 easily by a few men. Initially, the tower is lifted just belc)w the hin.-es 26 until it is high overhead, and then, using the upper half tower as a pike pole, the lower half tower is pushed to an uprigh-t position as shown in dot-' dash lines in FIG. 2 in which position the upper tower 60 half lies close to the vertical lower tower half and the erection cable 38 passes from the V-groove 30 in the end of auxiliary boom 29 under a pulley 41 carried by line 44 to a rear stake 42. A winch 43 is connected to the base plate 23 and r,5 to the xope or line 44 and by tightening winch 43 the erection -cable is ti@ghtened, and the upper tower half raised initially by auxiliary boom 29 acting as a lever and then by the erection boom 28 ac-ting as a lever abdut the points 26-26'. Before raising the upper tower half, n is connected 70 however, the third rail of tower Sectio 8 by a quick release pin 20 to the remaining base hinge bracket 25. The guy lines 6 and 7 can be used to keep the upper and lower tower halves in proper alignment -while raising the tower and also position the tower 7,5 so that it is vertical. As the tower reaches vertical
[3]5 position, the third rail of upper tower s--.c@tion 11 will align with and rest upon centering plu@,- 45 provided in the third leg of lower tower section 11. Tightening the gi-iy lines 6 and 7 and the antenna catenaries 3, 5 and 5' completes the tower and antenna erection, the entire erecting operation usually taking less than a couple of hours without a@-iyone ,- etting off the ground. Similarly, by reversing the above steps, the antenna can @be taken down aiid easily shipped in a pick-up truck to another location, the total tower pltis equipment, including antenna and lines, not usually exceedin-, two to four hundred pouids, depeiidin.- on the height of the tower and -type of anterna. Although tle novel tower is shown suppor-ting a highfrequency hor-@zontally polarized broad-band, for exariple, four to thirty-two meoacycle antenna, obviously it may ba used for other purposes, such as a light tower or for radio relayin.-, etc. Since maily changes cotild be made in the above construction and many apparently widely different embodiments of this invention could be made without departing froni the scope thereof, it is intended that all matter contained in the above description or shown in the accompanyin- drawin.as shall be interpreted as illustrative and not in a limiting sense. What is
