Abstract:
A mast that includes an omnidirectional antenna disposed therein and a GPS antenna coupled with the mast. Both the omnidirectional antenna and the GPS antenna preferably are protected from the environment, with the omnidirectional antenna being located above the GPS antenna when the mast is positioned vertically.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The invention relates generally to an omnidirectional antenna and GPS antenna that is coupled with a protective mast. 
         [0003]    2. Description of the Related Art 
         [0004]    Radio antennas and antennas for receiving Global Positioning System (GPS) signals are a common site on both mobile (e.g., vehicles) and stationary objects (e.g., transmission towers). Sometimes, it is desirable to receive both radio and GPS transmissions at a single location or mobile object. 
         [0005]    For a variety of reasons, the reception of both radio waves and GPS transmissions often are accomplished by using two separate antennas. Thus, for example, an automobile often will have both a standard “whip” antenna for radio wave reception and a separate “fin” antenna for GPS reception. 
         [0006]    However, even single-unit, multi-frequency antennas are of limited use due to aerodynamic, space, and other considerations. Moreover, a difficulty in producing a combination GPS and radio antenna is that the electronics and mechanical structure for receiving the radio signal can interfere with the performance of the GPS antenna for receiving the GPS signal. 
         [0007]    Many antennas are made wholly of wire and/or metal. However, this construction is unsuitable for applications in which the antenna is likely to be subjected to harsh conditions. For example, haul trucks at a mine site are used in rugged terrain and under conditions that tend to bend, corrode, break, an otherwise impair the function of an ordinary metal antenna. Furthermore, exposure of a metal antenna to extra-vehicular sources of electrical current (such as lightning or even overhead power lines in the case of large trucks) can present a safety issue. 
         [0008]    Since it is desirable to have antennas at the highest point of an object in order to maximize reception, separate antennas for reception of radio and GPS signals often are placed at the highest part of a vehicle. However, this can lead to interference when both antennas are disposed at a similar height, and having two separate antennas can only increase the cost and time involved in maintaining and repairing antennas that become damaged. 
       SUMMARY OF THE INVENTION 
       [0009]    The invention relates in general to an antenna that combines a GPS antenna, an omnidirectional antenna, and a protective mast. More particularly, the invention involves an omnidirectional antenna that is at least partially encased by a mast and includes a GPS antenna that is coupled with the same mast and is at least partially encased by a protective cover. The omnidirectional antenna is located above the GPS antenna when the mast is used in its normal vertical position. 
         [0010]    Preferably, the cables connected to the omnidirectional antenna and the GPS antenna are housed within the mast so that they also are protected and isolated. Moreover, the mast most preferably is radio frequency (RF) transparent and made of low or non-electrically conductive material. 
         [0011]    In one aspect of the invention, the mast is flexible and the mast and protective cover comprise a radome. In other words, the mast and protective cover enable the antennas of the invention to resist bending forces, impacts, ultraviolet light, and all types of inclement weather. Moreover, encasing the antennas of the invention provides a stronger overall structure, as the nesting of the antenna within the mast “reinforces” the mast. 
         [0012]    The antennas of the invention are particularly useful in situations involving exposure to rugged conditions. Thus, for example, while exposure to sand, sun, rain, ice, dust, rock impacts, and tree braches would bend/deform, corrode, or break a typical metal antenna, the embodiments of the invention both maintain structural integrity and provide improved multi-reception functionality under harsh conditions. 
         [0013]    Various other purposes and advantages of the invention will become clear from its description in the specification that follows. Therefore, to the accomplishment of the objectives described above, this invention includes the features hereinafter fully described in the detailed description of the preferred embodiments, and particularly pointed out in the claims. However, such description discloses only some of the various ways in which the invention may be practiced. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  is a schematic view of a wireless network utilizing antennas of the prior art. 
           [0015]      FIG. 2  illustrates in sectional view a first embodiment of the invention. 
           [0016]      FIG. 3  depicts in side elevational view a second embodiment of the invention, with the antenna and GPS receiver being shown inside the mast in phantom line. 
           [0017]      FIG. 4  shows a schematic of a haul vehicle with an antenna of the invention mounted in a preferred location. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0018]    The invention relates to providing an omnidirectional antenna and GPS signal-reception antenna in conjunction with a single protective mast. The omnidirectional antenna and GPS antenna components are situated along the mast such that interference is minimized, yet both components can be positioned higher than the object to which they are attached for optimal reception. 
         [0019]    Referring to  FIG. 1 , the numeral  10  identifies a typical wireless network arrangement involving a haul truck, a repeater tower, and central dispatch in accordance with the prior art. The haul truck  12  includes a dump bed  14  having an overhang  16 , a cab  18 , a boarding platform and rail  20 , a GPS antenna  22  and a UHF antenna  24 . As indicated by arrow A, the overhang  16  of dump bed  14  elevates during use. Thus, GPS antenna  22  and antenna  24  will become lower than the overhang  16  during normal operation of truck  12 , which can lead to impaired signal reception. Moreover, neither antenna  22  nor antenna  24  are protected from the elements or against impact (e.g., from a rock outcropping or tree branch). 
         [0020]    Turning to  FIG. 2 , an antenna of the invention is shown. The antenna  30  includes a tubular  32  mast containing an omnidirectional antenna  34  and a GPS antenna  36  encased in a protective cover  38  that is coupled to the mast  32 . Omnidirectional antennas include, for example, whip, vertical dipole, discone, and horizontal loop antennas. Near the lower end of the mast  32  is a sleeve  40  into which the mast is coaxially disposed and that allows the mast to be adjusted in height as indicated by arrow B. 
         [0021]    The receiver  36  is coupled to the mast  32  such that it is below the omnidirectional antenna when the mast is in a vertical position. This positioning of the antenna  36  and antenna  34  on the same mast has been found to lessen interference and yet provide for optimal reception capabilities. Preferably, antenna cable  42  and antenna cable  44  are disposed inside the mast  32 , which is substantially non-conductive (i.e., little or no electrical conductivity). 
         [0022]    Also preferably, the mast  32  and/or protective cover  38  is flexible and a radome. A radome is a structural, weatherproof enclosure used to protect an antenna. What distinguishes a radome structure from other structures is that the material used in building the radome allows a relatively unattenuated electromagnetic signal between the antenna inside the radome and outside equipment. In other words, RF transparency is characteristic of a radome. Using conventional whip antenna materials (i.e. steel, aluminum, etc.) would block most if not all of the antenna signal. Moreover, a radome protects the surfaces of the antenna from the effects of environmental exposure (i.e., wind, rain, sand, UV, ice, etc.). Fiberglass or an acetal resin engineering plastic, such at that sold under the DELRIN brand name, are examples of flexible radome materials. 
         [0023]      FIG. 3  illustrates a second embodiment of the invention, wherein a GPS antenna  50  and omnidirectional antenna  52  are integrated interior to a single radome mast  54 . For added protection and insulation, cable  56  connected to the omnidirectional antenna  52  and cable  58  connected to the antenna  50  also are housed within the mast  54 . A power source, if needed, also may be included inside or outside the mast as shown. The mast  54  further includes a mounting means (such as clamps  60 ) at a lower end thereof. 
         [0024]      FIG. 4  depicts an embodiment of the invention in use on a vehicle, haul truck  70 . The truck has a dump bed  72  with an overhang  74 , a cab  76 , and a boarding platform and rail  78 . Because mounting an antenna on any part of the dump bed (including overhang  74 ) would result in the problems incurred by the vehicle of  FIG. 1 , an omnidirectional antenna encased in a mast  82  and a GPS antenna  84  coupled to the mast  82  below the omnidirectional antenna are secured to a portion of railing  78 . 
         [0025]    Thus, the mast  82  is secured to vehicle  70  such that both the antenna  82  and the antenna  84  are higher than the vehicle  70  and overhang  74 . 
         [0026]    Various changes in the details and components that have been described may be made by those skilled in the art within the principles and scope of the invention herein described in the specification and defined in the appended claims. Therefore, while the present invention has been shown and described herein in what is believed to be the most practical and preferred embodiments, it is recognized that departures can be made therefrom within the scope of the invention, which is not to be limited to the details disclosed herein but is to be accorded the full scope of the claims so as to embrace any and all equivalent processes and products.