Abstract:
A monopole tower with antennas mounted near the top thereof is configured as either a tree such as a palm, or a pine, or other variety of tree having foliage that emulates that of natural trees so that the tower blends inconspicuously into the local surroundings. In the palm tree embodiment, one or more frond mounting assemblies encircle the monopole tree trunk, and include a plurality of receivers for holding palm fronds that are oriented at different angles relative to the monopole trunk. Individual fronds are made up of frond leaflets that are positioned along a frond spine member to closely emulate the appearance of a natural palm frond.

Description:
BACKGROUND OF THE INVENTION 
     1. Technical Field 
     This application relates to a tower that is configured as a tree or other plant species, and is arranged for the mounting and support of antennas thereon. The tower and antennas are arranged in a manner to intentionally obscure the visual appearance of the antennas to a ground level viewer. 
     2. Background Art 
     Cellular telephone technology requires that a user be within line of sight distance of an antenna that sends and receives signals to and from the user&#39;s telephone. It is routine practice to maximize the geographical area, or cell, served by each antenna by installing the antenna at an optimum height. In urban areas, antenna sites were often available on existing tall structures such as buildings or existing antenna towers. As the area covered by cellular telephone systems has expanded into suburban and rural areas, it has become necessary for cellular communications companies to erect increasing numbers of antenna towers. 
     New antenna installations typically employ a monopole antenna that consists of an upstanding post some 40 to 125 feet in height. One or more antenna sets are mounted near the top of the post. The stark appearance of such monopole antennas frequently generates intense local opposition to any antenna site that might be proposed. Much of the local opposition to proposed monopole antenna sites can often be blunted if the antenna structure is camouflaged so as to give the visual appearance of a tree. Such camouflaged antenna structures must not interfere with signal transmission or reception, must withstand the extremes of local weather, and must blend inconspicuously into the local setting. 
     Antenna support structures in the form of a tree are described in U.S. Pat. Nos. 5,611,176 and 5,787,649. The first patent, U.S. Pat. No. 5,611,176 to Juengert et al, describes an antenna support structure in the form of a white pine tree. The tree trunk portion of the antenna structure consists of a hollow metal post having antenna assemblies mounted thereupon adjacent the top end. Limbs, branches and foliage situated below the antenna assemblies largely hide the antennas from view. A layer of epoxy that is textured and colored to mimic pine bark covers the post exterior. 
     The second patent, U.S. Pat. No. 5,787,649 to Popowych et al, describes a monopole antenna tower that simulates a tree, and is capped by electronic antennae and equipment. A tapered steel post of polygonal cross section simulates a tree trunk, and foliage components that simulate either a palm tree or a pine tree are secured thereto. The lower portion of the monopole palm tree trunk is covered by fiberglass cast as half tubes within a mold to simulate natural palm bark. Polyurethane, also cast to simulate natural tree bark, covers the upper portion of the monopole trunk. Branches and boughs that simulate tree foliage are attached to the monopole trunk by way of tubular pipe stubs or receptors that are welded to the monopole trunk. A male branch member is inserted into the tubular receptor, and is secured therein by a fastener such as a bolt. 
     While the antenna support structures of the prior art are functional for their intended purpose, they are expensive to construct and lack the emulation of natural foliage that is desired for the antenna towers to blend inconspicuously into the local surroundings. This invention fills that need. 
     Hence, it is an object of this invention to provide an antenna tower that has a natural tree plant-like appearance. 
     It is another object of this invention to provide a means for mounting foliage and antennas to the trunk of a tree-like antenna tower. 
     Yet another object of this invention is to provide a system for mounting antennas on a pine tree antenna tower in a way that the antennas are minimally obstructed by foliage, but arranged to be visually unobtrusive. 
     Another object of this invention is to provide more natural looking fronds for a palm tree antenna tower, and a method for making those fronds. 
     A further object of this invention is to provide an antenna tower that is formed as a saguaro cactus. 
     SUMMARY OF THE INVENTION 
     This invention provides a tree plant-like antenna tower that can be formed either as a palm, tree or a pine, or other tree species, or as a saguaro cactus. The tree plant trunk or stem is formed from a tapered or constant diameter metal, concrete or fiber reinforced composite pole clad with a polymeric composition to mimic the appearance of a the natural tree plant. In the palm tree embodiment, a bracket assembly holding a plurality of individual fronds is bolted to the pipe, and a second bracket assembly holding antenna mounting assemblies that allow the antennas to be fully rotatable. Artificial palm fronds are fabricated using a fiberglass rod core with leaflets mounted thereon. The leaflets may be oriented progressively from a horizontal attitude at the frond base to a vertical attitude at the frond tip to more accurately represent the frond structure of a real palm tree. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 is an illustration of an antenna structure according to this invention formed as a palm tree; 
     FIG. 2 is an alternative embodiment of the antenna structure depicted in FIG. 1, adapted to accommodate a second set of antennas that are mounted within a simulated growth pod; 
     FIG. 3 is an illustration of an antenna structure according to this invention formed as a pine tree; 
     FIG. 4 is a side view of a bracket sub-assembly arranged to securely hold a plurality of palm fronds; 
     FIG. 5 is a plan view of the bracket sub-assembly of FIG. 4; 
     FIG. 6 is a plan view of a second bracket sub-assembly for the mounting of antennas to the antenna tower; 
     FIG. 7 is an illustration of a palm frond that forms the foliage of the tree antenna structure of FIG. 1; 
     FIG. 8 is a side view of a frond leaflet that makes up a part of the frond illustrated in FIG. 7; 
     FIG. 9 is a sectional view of the frond leaflet of FIG. 8 taken along lines  9 — 9  of FIG. 8; 
     FIG. 10 is a plan view of the frond leaflet of FIG. 8; 
     FIG. 11 is an illustration of a frond tip that makes up the terminus of the palm frond depicted in FIG. 7; 
     FIG. 12 is an oblique view of a shaft insert that allows orientation of individual frond leaflets; 
     FIG. 13 illustrates another embodiment of the shaft insert of FIG. 12; 
     FIG. 14 is a plan view of another embodiment of a frond leaflet making up a part of the frond illustrated in FIG. 7; 
     FIG. 15 is a break away view of foliage suitable for use with the embodiment of FIG. 3, as well as the manner in which the foliage is mounted; 
     FIG. 16 is a detail view of the foliage mounting means of FIG. 15; 
     FIG. 17 is an illustration of an antenna structure according to this invention formed as a saguaro cactus; and 
     FIG. 18 is a plan view of the antenna structure of FIG.  17 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A first embodiment of this invention in which the antenna tower is formed as a simulated palm tree is illustrated in FIGS. 1 and 2. The tower structure is shown generally at  10 , with a tubular pole  12  serving as the trunk of the palm tree. Pole  12  may be fabricated from metal, concrete, or a fiber reinforced composite, commonly referred to as FRC. By way of illustration, pole  12  may suitably comprise a tubular steel pipe having a diameter of eighteen to twenty four inches with a wall thickness ranging from three-sixteenths to one-half inch. The overall height of the tree antenna tower  10  may range from about forty to more than two hundred feet. 
     The lower end of pole  12  is secured fixed to a support so that the pole is held in a secure upright position. That may be done, for example, by burying the lower end of the pole in the ground or by welding the pole end to a butt plate  14  which, in turn, is fixed to a foundation  15  that suitably may be a concrete monolith. Ports  17  are provided near the bottom of pole  12  to allow entry of communications cables that pass through the interior of pole  12  and connect to antennas  20  which are mounted on the pole near the top thereof. Antennas  20  are attached to pole  12  by means of an antenna bracket sub-assembly  24  that is shown in more detail in FIG. 6. A plurality of palm fronds  26 , suitably on the order of sixty, are attached to pole  12  adjacent to antennas  20  by means of frond bracket sub-assemblies  27  which are shown in more detail in FIGS. 4 and 5. The top of pole  12  is closed by a weatherproof cap  28  to protect the wiring and other electronic components that are located within the pole. Also, the exterior of pole  12  is clad by a layer of molded and colored urethane or other suitable polymer to simulate the texture and appearance of a real tree trunk. 
     The realistic appearance of the cladding that forms the surface of the tree plant trunks, and of the tree branches as well, is obtained first by forming a mold from tree plant parts, either bark or branch, of the pine, or palm, or other plant species tree that is being emulated. Segments of branches or bark are then cast in the mold from a polymeric material such as polyurethane. The surface of the simulated tree plant part is colored to match the local foliage. Coloring is preferably accomplished in a two step fashion. A pigment or other coloring agent is added to the polymeric material used to make the casting to obtain the base coloration of the tree part. Then, darker highlights are added by painting accent areas to more closely match the coloration of the natural tree part. 
     FIG. 2 illustrates another embodiment of the palm tree antenna tower shown in FIG.  1 . In this embodiment a pod structure  33  that mimics the new growth pod, or pineapple, found on palm trees is mounted underneath the frond brackets  27 . Pod structure  33 , shown in partial break away view, is arranged for the deployment of a set of antennas  35  therein. That set of antennas may be the only antennas carried by the tree tower, or it may be a second set of antennas together with associated hardware. Pod structure  33  preferably is of a generally hemispherical shape, open at the top, and is molded of a fiber reinforce composite or other material that is essentially transparent to electromagnetic radiation. It is preferred that pod  33  be molded in either two or three segments that connect along joints  37 . One or more drain ports  38  are provided at the bottom of pod  33  to prevent rain water from collecting therein. The pod segments are secured to pole  12  by means of clamp means  39  at the lower margin of pod  33 . 
     Details of frond bracket sub-assembly  27  are shown in FIGS. 4 and 5. Bracket  27 , shown in side view in FIG. 4, comprises a metal collar  42  that fits around and clamps to pipe  12 . A number of receiver fixtures  43  are fixed to collar  42  by welding or other suitable means. In a preferred embodiment, fixtures  43  comprise short lengths of square pipe oriented at various angles  46  to the horizontal. Angle  46  may range from about 90° above the horizontal to about 30° below the horizontal. Collar  42  is preferably formed in segments  48 , suitably three, that are fastened together at junctures  49  by means of bolts  51  to tightly clamp around the exterior of pipe  12 . The vertical height of collar  42  may conveniently range from about six to twelve inches, and each collar segment  48  may have attached thereto as many as ten or more fixtures  43  to hold an equal number of fronds  26 . 
     It is preferred to mount a pair of brackets  27  on pole  12 , one directly above, and one directly below the antenna bracket sub-assembly  24  that is shown in FIG.  6 . Like frond holding brackets  27 , the antenna bracket  24  comprises a collar that is made up of multiple segments  55  that are fastened together at junctures  57  by means of bolts  58 . Each bracket segment  55  is provided with an antenna mount  61  to which is attached an antenna arm member  63 . Bracket  24  is freely rotatable about pole  12  so as to allow convenient angular orientation of the antenna structure. 
     FIG. 7 illustrates an artificial palm frond that is fabricated according to this invention. It is constructed of a material, preferably a thermoplastic such as polystyrene or polyvinyl chloride, that does not interfere with the radio signals that are transmitted to and from the antennas. The frond includes a flexible rod core  71  that is suitably fabricated from a glass fiber reinforced resin. Rod core  71  is preferably of uniform polygonal cross section, has a plurality of frond leaflets  73  mounted thereon, and terminates at a frond tip  75  which is adhesively secured to an end of rod core  71 . The stem end of rod core  71 , opposite to the frond tip, terminates in a round or polygonal (shown here as square) metal tube member  77  (FIG. 11) that snugly fits into any one of fixtures  43 . Tube member  77  is secured within a fixture  43  using adhesives, or preferably by means of a pin inserted through holes provided in the side walls of fixture  43  and through bore  78  of tube  77 . 
     As is best shown in FIGS. 8 and 10, individual frond leaflets  73  have a pointed tip end  81  and a wider, flattened basal end  83 . The frond leaflets  73  preferably display a generally triangular or shallow V-shape in cross section as is shown in FIG. 9. A hole  85  through basal end  83  is oriented perpendicular to the flattened sides of end  83 . It is preferred that hole  85  be circular to accommodate a generally cylindrical insert  87  that is shown in perspective view in FIG. 12. A bore  89  that generally conforms in size and shape to the polygonal cross section of rod  71  is formed through insert  87 . The axis of bore  89  is parallel to, and preferably is aligned with, the cylindrical axis of hole  85 . 
     Individual leaflets are mounted upon rod core  71  in an alternating fashion, left and right, by threading core  71  through the bores  89  of the individual leaflets. The polygonal shape of rod core  71  and conforming bores  89  hold and maintain each frond leaflet in a set orientation. Natural palm fronds display a regularly changing orientation of the frond leaflets. Individual leaflets are oriented generally horizontally at the frond stem end near the trunk, and gradually progress to an approximate vertical orientation at the frond tip. The provision of the cylindrical insert  87  in the basal end of each frond leaflet  73  allows the orientation of each frond leaflet to be incrementally changed simply by angularly adjusting the position of insert  87  within hole  85 . Insert  87  is then fixed at the desired angular position within hole  85  by gluing the insert into place. Alternatively, insert  87  and hole  85  can be dimensioned such that the insert forms a tight, press fit within the hole. A progressive adjustment of the angular position of the insert may also be accomplished by providing the outer cylindrical surface of insert  85  with small, uniform notches or serrations  91  as is illustrated in FIG.  13 . corresponding serrations would then be provided on the inner surface of basal end hole  85 . 
     Another embodiment of the palm leaflets is illustrated in FIG.  14 . The leaflets  100  of this embodiment are generally similar in size and shape to the leaflets illustrated in FIGS. 8 and 10. They differ, however, in an insert (element  87 ) is not used, and the hole or bore  102  at frond leaflet end  103  is sized and shaped to conform to the polygonal cross section of rod  71 . As before, individual frond leaflets  100  are mounted upon rod core  71  in an alternating fashion, left and right, by threading core  71  through the bores  102  of the individual leaflets. This embodiment does not allow for the progressive change in the orientation of individual frond leaflets from the stem end of the frond to its tip. 
     Turning now to FIG. 3, there is illustrated another embodiment of this invention in which the antenna tower is formed as a pine tree  90 . This antenna tower preferably uses a pole  91  having a regular or step taper, decreasing in diameter from bottom to top, to more closely mirror the natural taper of a pine tree trunk. As with the embodiment of FIG. 1, the bottom of pole  91  is secured to a butt plate  93  which, in turn is fixed to a foundation  95 . A layer of colored polymeric material, such as polyurethane, is molded from an actual tree and is glued to the exterior surface of pole  91  to give the appearance of a real tree trunk. Ports  99  are provided near the bottom of pole  91  to allow entry of communications cables that pass through the interior of pole  91  and connect to antennas  101  which are mounted on the pole near the top thereof. Antennas  101  are attached to pole  91  by means of the antenna bracket sub-assembly  24  that is detailed in FIG.  6 . It is preferred that antennas  101  be placed to extend outward from the tree trunk pole  91  a distance at least as great as is the length of those tree branches  105  which are located in the proximity of, both above and below, antennas  102 . So long as there is foliage between the antenna and pole  91  there is created enough visual distraction to render the antennas unobtrusive to the casual viewer. The installation can be made even less noticeable by painting the antenna elements in a camouflage pattern of browns and greens. 
     FIG. 15 shows in a break away view of the tree branches that are attached to the trunk pole  91 . The artificial branches  105  comprise a basal tube mount  107  that serves as a junction between a receiver stub bracket  109 , similar to fixture  43  shown in more detail in FIG. 16, and a branch spine  111 . Branch spine  111  is fabricated from a structural plastic, such as a glass fiber reinforced resin, by forming a split mold using as a pattern an actual tree branch trimmed of foliage, and with the side branches cut to short stubs  112 . In like fashion, side branches  114  are cast separately and are later attached to a stub branch  112  by means of connectors  115 . Artificial foliage  117 , similar to that used in artificial Christmas trees except made with plastic windings rather than metal, are then attached to the side branches  114 . The resulting tree antenna tower is remarkably unobtrusive, particularly in locales having natural pine trees in relatively close proximity. As with the embodiment of FIG. 1, the materials from which the limbs, branches and foliage have been fabricated are selected so as not to interfere with the transmission of radio signals to and from the antennas. 
     Referring now to FIG. 16, there is shown two different bracket means  120 ,  122  for attaching foliage branches to a main tree trunk pole  91 . Bracket means  120  includes a plate  123  that may be attached to trunk  91  by means of studs  124  which pass through plate  123  and are threaded into tapped holes in the wall of pole  91 . A rod member  126  extends outwardly from plate  123  to connect with and support a tree branch  111 . Tree branch spine  111  may connect to rod  126  using sleeve  107 , as is shown in FIG. 15 or, if branch  111  is large enough, may be inserted into a hole  127  that is provided at the basal end of branch spine  111  as is illustrated. The branch  111  is secured to rod  126  by means of a pin or bolt which passes through holes that are provided in both the pin and branch. 
     Bracket means  122  comprises a box member  129  that is attached to trunk  91 , suitably by welding. A C-shaped channel fixture  131  is sized to fit over box  129 , and is attached thereto by means of a bolt or pin member  133  which passes through holes provided in box  129  and channel.  131 . As in bracket  120 , a rod member  127  extends outwardly from channel  131 , and is arranged for connection to a tree branch in the manner previously described. The angle to the horizontal made by rod  127  may be varied to conform to the branch pattern displayed by the tree species that is being emulated. 
     Referring now to FIGS. 17 and 18, there is shown another embodiment of this invention in which an antenna tower  140  is structured in the form of a saguaro cactus. The saguaro cactus is native to the Sonoran desert area of the American southwest, and grows in nature to heights of 50 feet or more. In this embodiment, the main trunk or stem  142  comprises a pole of generally uniform diameter that is fabricated from metal, concrete, or a fiber reinforced composite. The lower end of stem  142  is attached to a plate  144  or other suitable mounting means to position the tower in a stable, upright position. The exterior of stem  142  is clad with a layer of molded and colored urethane or other suitable polymer to simulate the surface of an actual saguaro cactus. The exterior cladding is obtained by forming a mold from the surface of an actual cactus and making a casting in that mold from a polymeric material such as polyurethane. 
     A plurality of branches, preferably three, extend from stem  142 . Those branches,  146 ,  147 , and  148 , are positioned at the mid to upper level of stem  142 . As is shown best by branch  148 , each branch includes a generally horizontal segment  150  that extends outwardly from the stem, and a longer vertical segment  151 . The branch surfaces are covered with a cladding formed in the same way as that used for the stem  142 . In a preferred embodiment (best shown in FIG.  18 ), the three branches are positioned equiangularly 120° apart around stem  142  so that the vertical segments  150  of each branch form a generally equilateral triangle. 
     A antenna array that comprises at least one, and preferably a pair, of antennas  155  are mounted within the vertical segment  151  of each branch. Another antenna array  157  may be mounted within stem  142  itself, preferably near the top thereof. The branches may be positioned on stem  142  such that a portion of the vertical segment  151  of each branch overlaps. That arrangement allows the height of antennas  155  in each branch to be the same, although the antennas can be placed at different heights as well. It is necessary that the portion of the branches (and of stem  142 ) that are adjacent the antenna array be fabricated from a material that will not interfere with the transmission of radio signals to and from the antennas. For that reason it is preferred that, at least the vertical segment of branches  146 ,  147  and  148 , and the upper portion of stem  142  be fabricated from a structural polymer such as a fiber reinforced resin. 
     The invention has been described in relation to preferred embodiments thereof that are illustrated in the various Figures. It must be understood that other variations of the invention will be apparent to those skilled in the art.