Abstract:
A multi-legged antenna mounting system for vehicles, to resist high wind loading on the antenna, having at least three mounting legs positioned to the vehicle by clamping members or by magnetic attracting members. The legs of the mounting system are secured to an antenna connecting assembly unit in order that a plurality of the legs are adjustably secured for various angular dispositions with respect to the vehicle. One of the legs of the mounting system comprises the antenna element.

Description:
BACKGROUND OF THE INVENTION 
     I. Field of the Invention 
     The present invention relates generally to the field of antenna mounts and more particularly to antenna mounting systems for vehicles wherein the antennas which are utilized present very high wind loads at highway speeds which causes extreme pressure on the antenna mounting system affixed to the vehicle. The antenna system of the present invention typically will lock and secure the antenna to the trunk lid of the vehicle by a unique stabilizing and reinforcing antenna mounting means. 
     II. Description of the Related Art 
     Historically, mobile radio operators have been forced by available mechanical support limitations to compromise the radiation efficiency of high wind load antennas typically used in the high frequency bands by mounting them on the periphery of the vehicle. Typical of such peripheral mounting mechanisms would encompass the front and rear bumpers of the vehicle, inasmuch as this is a strong point on most vehicles. However, from a radiation efficiency standpoint, the optimum location on the vehicle for any antenna is always near the horizontal center of mass of the vehicle body. 
     Mounting antennas on the trunk or hood of the vehicle, these being convenient locations on most vehicles, however, yields nearly the same radiation efficiency of a roof center mounting while providing cost savings and mounting ease opportunities not easily achieved with roof mounting. An important advantage of trunk lip mounting over roof center mounting for many antenna types is the increased radiating element length that is possible when the bottom of the antenna may be placed doser to the ground. This increases the physical length of the antenna without exceeding the normal legal over-the-road height limit, typically at 13′6″, for obstruction clearance. For radiation efficiency purposes, the optimum physical length of vertical antennas, which are frequently used in mobile radio service, is ¼ wave length. Any physical length for a given frequency that is less than ¼ wave length will be electrically sub-optimal. The practical limit for the physical length of a mobile radio antenna is established only by the actual overhead clearance in the area being traversed by the vehicle. However, as noted above, the legal limit for vehicles operating on public roads is typically 13′6″ from the ground to the top of the antenna. 
     Therefore, it will be obvious that some means of approaching the electrical equivalence of a mobile radio antenna at lower frequencies without exceeding the physical height restriction above the ground is quite desirable. In order to achieve a good radiation efficiency for an antenna, the addition of a relatively large diameter coil, called a loading coil, somewhere along the length of the antenna is required. With the addition of a loading coil, the optimum physical antenna length may now be physically constructed to a shorter form factor. It is this form factor that can produce significant wind load at highway speeds on mobile radio antenna installations, especially those operating below 14 MHz. 
     Not only will vertically polarized mobile radio antennas benefit by the present invention, but horizontally polarized mobile radio antennas can achieve the same physical and radiation efficiency benefits by the use of the present invention. Horizontally polarized mobile radio antennas typically yield wind loads approaching those of vertically polarized antennas and, in addition, overhead clearance questions may also be a consideration in any stacked array antenna system of any horizontally polarized antenna systems. 
     The prior art is replete in antenna mounting systems and such systems have been used with antennas of many different configurations. Typical of many vehicle antenna mounting systems are magnetic mounts such as shown in U.S. Pat. No. 4,543,584 to Leer which disclose a horizontally disposed triangular mounting system having magnets at the distal ends of the mount legs for securing to a metal portion of a vehicle. This type of mount, however, will not support a high wind load antenna. 
     In U.S. Pat. No. 3,967,275 to Wagman and U.S. Pat. No. 4,249,182 to Rupley, clamp-on antenna mounts are shown which are typically clamped to a rearview mirror which is in turn attached to the side of the vehicle cab. While these antenna mounts show a multi-leg attachment system, the mounts are not designed to support high wind load antenna systems. 
     A typical truck lid mounting system is shown in U.S. Pat. No. 4,028,706 to Dolle, but, again, the system is quite flimsy and will not sustain high wind loading stresses. 
     BRIEF SUMMARY OF THE INVENTION 
     In accordance with the present invention and the contemplated problems which have existed and continue to exist in this field, the objectives of this invention are to provide a multi-legged antenna mounting system for vehicles which may typically be mounted to the vehicle trunk wherein at least three mounting legs are positioned along the periphery of the trunk lid by suitable clamping members and thence terminate at an insulated antenna connecting assembly unit. The legs of the antenna mount system are capable of being positioned with respect to the insulated antenna connecting assembly unit in a variety of angular dispositions to enable the legs to be affixed to the vehicle trunk lid. Each leg at the distal end thereof terminates in a deck mounting unit which is designed to fixedly mount each leg to the lid. It is anticipated that prior art mounting systems for this purpose will be utilized with the present invention. For stability sake, the antenna is incorporated as one of the mounting legs. All of the legs, including the antenna, will be incorporated into the insulated antenna connecting assembly unit to provide the structural stability needed for the high wind loading capabilities of the present invention. 
     The invention does not block access to either the trunk interior of the vehicle or to the hood interior if the unit is mounted on the hood of the vehicle, inasmuch as the antenna system simply moves to a more or less horizontal position when the trunk lid or the hood is opened. The various components of the invention are commonly used materials and the vehicle deck mounting units are standard off-the-shelf components. By using at least three mounting legs to support the unit, one of the legs being the antenna itself, there is a certain amount of functionality, endurance and resilience which occurs that exceed that of the sum of the mounts by orders of magnitude. Antennas of any reasonable size may be mounted as part of the system disclosed herein and will be fully supported during normal high wind load conditions. The present invention also contemplates the use of magnetic foot mounts for securing the legs of the assembly to the vehicle, as opposed to mechanical lid mounts, and it has been found that such magnetic mounts, properly sized, will perform adequately in high wind load conditions. 
    
    
     Other objects, advantages and capabilities of the invention will become apparent from the following description taken in conjunction with the accompanying drawings showing the preferred embodiment of the invention. 
     SRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of the multi-point antenna mounting system of the present invention shown fixed upon a deck of a vehicle; 
     FIG. 2 is a partial elevation view of the insulated antenna connecting assembly unit with close-up views of the connecting mechanism of the support legs; 
     FIG. 3 is a top view of the insulated antenna connecting assembly unit with the antenna in section view; 
     FIG. 4 is a partial section view of a typical vehicle deck mount unit of the prior art showing the interconnection of one antenna support leg mounted thereto; and 
     FIG. 5 is a partial perspective view of a support leg terminating in a magnet mount. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to the drawings wherein like reference numerals designate corresponding parts throughout the several figures, reference is made first to FIG. 1 showing the multi-point antenna mounting system  11 . FIG. 1 discloses a three point mounting system, however, it is contemplated that under high wind loading conditions it may be necessary to have four or more support legs for the system and such is contemplated herein. The system  11  comprises an antenna element  12  of any suitable design and two or more struts  13 . The respective distal ends  14  of the antenna element  12  and the struts  13  are mounted to commercially available deck mount units  15 . For securing purposes, the deck mount units  15  would then be mounted in typical fashion around the peripheral edge  16  of the vehicle deck lid  17 . A typical type of deck mount unit  15  is one made by Comet Co., Ltd., Model RS-9. This type of mount unit comprises an upper mount body  17  and a lower mount body  18  which are interconnected by means of clamping screws  19 , which connect respective connecting ears of the upper and lower mount bodies to retain the bodies in respective alignment with one another. The mount units  15  are attached to the vehicle deck lid  17  by means of a reentrant clamping flange  22  which encompasses the peripheral edge  16  of the vehicle deck lid  17 . Securing the clamping flange to the deck lid will typically be a clamp fastener  23  which projects through the clamping flange  22  and impinges upon the underside of the deck lid  17 . Each of the distal ends  14  of the respective struts  13  and the distal end of the antenna element  12 , are respectively connected to the mounting plates  24  of each deck mount unit  15 . The specific mounting arrangement is clearly shown in FIG.  4 . 
     The distal end  14  of each strut  13  will terminate in suitable mounting components such as a 45° elbow joint  25  and a 90° elbow joint  26 . Obviously, the angular requirements of the mount will be dictated by the height of the insulated antenna connecting assembly unit  27  supporting and placed around the antenna element  12 . The lower end of elbow joint  26  will be typically hollow and will have placed therein a tubing spacer  28  firmly cemented therein for the purpose of spacing apart retaining washers  29 . Placed through aperture  31  in the mounting plate  24  is a securing bolt  32  which terminates in a nut  33  so as to flank the retaining washers  29 , and to maintain the distal ends of struts  13  and the distal end of the antenna element  12  firmly against the mounting plate  24  of the deck mount unit  15 . It should be noted that the struts  13 , along with the various fittings  25  and  26 , are contemplated to be made from chlorinated polyvinyl chloride tubing (CPVC) which is easily obtainable on the commercial market. This type of tubing is of extremely durable dielectric material and does not alter the radiation characteristics of the antenna. 
     It is noted that the struts  13  may be made to various lengths to conform to the vehicle mounting requirements, and that the struts  13  are adjustably mounted to both the deck mount unit  15  and to the connecting assembly unit  27  so as to be angularly adjustable to present the antenna element in a vertical orientation. 
     Maintaining the entire structure in a rigid high wind resistant loading configuration is the insulated antenna connecting assembly unit  27 . As seen in both FIGS. 1 and 2, the struts  13  terminate in an elbow joint  25  on a lower surface of the assembly unit  27  and are secured thereto by securing fasteners  34  which are placed within the elbow joint  25  much in the same manner as just described for the elbow joint  25  attached to the mounting plate  24 . The assembly unit  27  generally comprises a pair of identical molded high density, durable dielectric plates indicated by numeral  35  representing the upper plate member and numeral  36  representing the lower plate member. Each of the respective plate members  35  and  36  are generally rectangular in configuration with a suitable thickness, defining at least one edge surface  43 , to maintain a rigid configuration. Each of the plates has an antenna element access opening of U-shaped configuration indicated by numeral  37 . It should be noted that the access openings  37  are dictated in size solely by the diameter of the supported antenna element  12  whose size in turn is dictated by the desired transmitting characteristics of the installation. As seen in FIG. 3, the upper and lower plate members  35  and  36  overlie one another and firmly engage the antenna element  12  for secure support. In order to accomplish this task, the respective U-shaped access openings  37  are oppositely oriented with respect to one another so that the interior curved portion of the U-shaped opening of the plate members impinge upon the antenna element on opposite sides thereof, thereby securing the element within a defined opening within the juxtaposed plate members which are then subsequently secured to one another and to the struts  13  by the securing fasteners  34 . For maintaining the securing fasteners  34  in a locked position, lock washers  38  will be employed underneath the heads of the securing fasteners  34 . The securing fasteners  34  will then be tightened and threaded into a nut (not shown) which is embedded within elbow joint  25  adjacent the lower surface of the lower plate member  36 . The securing attachment of the fasteners  34  will be much in the same manner as described for the bolt and nut assembly of the deck mount unit  15 . 
     It will be seen that once the multi-point antenna mount system  11  is fully assembled, there is an extremely strong rigid mounting system available for antenna element  12  and that the antenna element also functions as one leg in the multi-point assembly. Such a system presents an extremely rigid and durable high wind loading antenna mounting system which has not been known in the prior art. 
     It may be that users of the present system will deem it advisable, in certain situations, not to utilize the type of deck mounting units  15  shown in the present drawings. It may well be that certain users will desire to place the antenna mount system  11  upon a surface of a vehicle by means of a magnet-type mounting system. Such a system is shown as an alternative embodiment in FIG.  5 . To accomplish this type of mounting system, the distal ends  14  of the respective elements would typically terminate in a joinder section  39  which would couple elbow joint  26  to a support base  41  which would terminate in a very strong magnetic mounting member  42 . In this fashion, the mount  42  would be placed upon the vehicle deck lid  17  and, depending upon the strength of the magnet, the antenna mount system would be firmly attached to the vehicle to achieve stability in high wind loading situations. 
     Therefore, the foregoing is considered as illustrative only of the principles of the invention. Further, various modifications may be made of the invention without departing from the scope thereof and it is desired, therefore, that only such limitations shall be placed thereon as are imposed by the prior art and which are set forth in the appended claims. 
     It is further contemplated that a combination of deck mount units  15  and magnet mount units  42  could be utilized should it be deemed appropriate to mount the system on a particular vehicle. For instance, one could use deck mount units  15  on each strut  13 , but also use a magnetic unit  42  on the antenna element  12  to secure it to the vehicle. This combination makes the system very adaptable to varying conditions.