Abstract:
An apparatus for manually maintaining the level of a radar antenna mounted on a stern pole affixed to the deck or transom of a vessel providing a platform pivotably mounted to a distal end of the pole and oriented to rotate about an axis substantially parallel to the centerline of the vessel. A controller at the lower end of the pole proximal to the cockpit permits manual adjustment of the horizontal angle of the radar antenna to maintain level due to heeling of the boat. The controller utilizes a first plate secured to the pole having a series of detent positions angularly spaced around and equidistant from a center point and a second plate rotatably secured at the center point. A grip handle projecting from the front surface of the second plate permits rotation of the plate when a cooperatively aligned release handle is grasped to withdraw one or more pins extending through holes in the second plate engage the detent positions. A pair of cable or rod linkages transmit rotation of the second plate to the antenna mounting platform.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to a system for mounting equipment such as a transceiver antenna unit to a vehicle. More specifically, the present invention is directed to a system and apparatus for manual adjustment of the antenna unit and mast orientation relative to a moving boat to maintain a generally horizontal orientation of the equipment relative to an external frame of reference. 
     2. Description of the Background 
     Marine radar equipment has become increasingly easy and inexpensive to use and consequently is found on more and more small vessels including small sailboats. As is well known, marine radar systems detect objects such as other vessels or land masses at or near the surface of the water by transmitting radio waves or microwaves and detecting the return wave signal that is reflected by objects in their path. In order to provide information about objects in a wide area, radar systems typically use rotating antennas to sweep an arc in the horizontal plane H ( FIG. 1A ,  1 B) partially or completely around the vessel while continually scanning for returned radio signals indicating the presence of an object. The range at which a radar system is capable of detecting the signal returned by an object is increased by elevating the antenna such that it is common to mount the antenna to the mast of a sailboat or to another point in the rigging above the deck in order to maximize operational range. 
     However, under sail a sailboat may be heeled over at an angle that can reach 45° or more in heavy winds, and 15° to 25° degrees under more common wind conditions. When a sailboat is heeled over the normally horizontal plane swept by a rotating antenna is likewise tipped or heeled to a similar angle, as depicted in  FIG. 1B . On the leeward or downwind side of the boat the radar signal is directed downward toward the water&#39;s surface, where it is reflected or deflected resulting in false or distorted return signals. On the windward side the radar signal is directed upward, well above any objects of concern for the sailor resulting in no return signal at all. In either case the effective range and ability of the radar system to detect objects at or near the surface of the water in proximity to the vessel is severely compromised. The vertical beam width of the transmitted radar signal is typically 25° such that any heel angle over 12.5° will negatively impact radar performance. 
     Mounting devices for radar antennae have been provided previously for use on sailing vessels. Some mounting devices such as that described in U.S. Pat. No. 4,659,044 to Armstrong fix the position of the radar antenna and do not facilitate any pivotal movement to compensate for heeling. More recently, prior radar mounts such as that described in U.S. Pat. No. 5,154,386 have included a pivoting system which allows the mounted radar antenna to swing freely and assume a horizontal orientation under the force of gravity. Other prior art radar mounts such as is described in U.S. Pat. No. 6,097,344 to Anderson utilize an actuator system to actively level a radar antenna mount. 
     Each of these prior radar antenna mounting devices has drawbacks and limitations. For example, fixed radar antenna mounts allow radar systems to be used in only the calmest conditions with minimal heeling of the sailboat, as described above. Gravity oriented pivoting radar antenna mounting devices allow the radar antenna to swing freely and constantly as the vessel moves through the waves (and even at anchor) negatively impacting the accuracy of the radar system and excessively wearing the antenna connections and electrical cabling as well as the moving parts of the mount itself. Passive dampening elements may somewhat limit swinging but add complexity and expense to the system, require maintenance and are prone to wear and malfunction under marine conditions. Actively actuated (motorized) systems eliminate the wear associated with uncontrolled swinging but require power and control systems which are equally prone to wear and failure in a marine setting. 
     Typically, wind conditions remain fairly constant on a minute to minute basis and a sailboat tends to heel at a constant angle or range while sailing in a given direction. Thus, it is unnecessary to constantly adjust the radar antenna. It is sufficient, and much easier, to adjust the angle once at each tack, and therefore more practical to provide a manual adjustment feature, thereby reducing wear and tear of cabling. 
     It would be desirable to provide a system for elevated mounting of radar antenna on a sailing vessel that is capable of being quickly and easily leveled manually by an operator and yet which avoids the limitations, cost, complexity and power requirements of prior systems and which also avoids the continuous and debilitating wear induced by uncontrolled swinging of the mount. 
     SUMMARY OF THE INVENTION 
     The present invention is, therefore, directed to a pole mounting device for a marine radar antenna that overcomes the foregoing deficiencies and others associated with prior mounting systems. The present invention provides an apparatus for manually maintaining the level of a radar antenna mounted on the top-end of a stern pole affixed to the deck or transom of a sailing vessel. The radar antenna is mounted atop a platform, and the platform is pivotably mounted on the top-end of the stern pole oriented to rotate about an axis substantially parallel to the centerline of the vessel as the vessel heels in varying wind conditions. A controller at the lower end of the pole proximal to the cockpit permits manual adjustment of the horizontal angle do the radar antenna to maintain level of the platform due to heeling of the boat. The controller is a heavy-duty unit permitting rapid and convenient angular and locking adjustment of the angle of the platform (and thus the antenna). 
     The controller utilizes a first plate secured to the pole having a series of detent holes angularly spaced around and equidistant from a center point, and a second plate rotatably secured to the first plate at the center point. A grip handle projects from the front surface of the second plate. The grip handle carries a cooperating squeeze-type release handle beneath it which, when squeezed, withdraws a pair of detent pins from the detent holes in the first plate. Thus, squeezing the release handle withdraws the detent pins extending through holes in the second plate permitting leveraged rotation of the second plate relative to the first. Relaxing the release handle re-engages the detent pins and locks the second plate in position. A pair of cable or rod linkages transmit rotation of the second plate to the antenna mounting platform at the distal end of the pole. Where cable linkages are utilized one or more sheaves may be used to route the cable path from the controller to the platform. A side mount bracket for the platform permits installation of a second, fixed antenna or device over the end of the pole. 
     The device allows an operator to quickly and easily adjust the angle of the radar antenna manually at each tack to a proper horizontal angle, and therefore reduces wear and tear on cabling, eliminates noise, and avoids the limitations, cost, complexity and power requirements of prior art systems. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       The objects, features, and advantages of the present invention will become apparent from the following detailed description of the preferred embodiments and certain modifications thereof when taken together with the accompanying drawings in which like numbers represent like items throughout and in which: 
         FIG. 1A  is a diagram of a radar equipped sailboat at rest. 
         FIG. 1B  is a diagram of a radar equipped sailboat heeled over in the wind. 
         FIG. 2  is a is a side view of a sailboat having a radar antenna mounted to a stern pole 
         FIG. 3A  is an elevation of a radar antenna mounted to a stern pole according to the present invention. 
         FIG. 3B  is a partial detail view of the pivot of the antenna mounting platform according to the present invention. 
         FIG. 3C  is an elevation of a radar antenna mounted to a stern pole according to an alternate embodiment of the present invention. 
         FIG. 4A  is a detailed partial perspective view if radar antenna mount to the top of a stern pole according to the present invention. 
         FIG. 4B  is an 
         FIG. 5  is a detailed partial perspective view if a control handle according to the present invention. 
         FIG. 6  is a front elevation view of a control handle. 
         FIG. 7  is a rear elevation view of a control handle. 
         FIG. 8  is a partial side perspective of view of a control handle. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the exemplary embodiment illustrated in the drawings and described below. The embodiment disclosed is not intended to be exhaustive or limit the invention to the precise form disclosed in the following detailed description. Rather, the embodiment is chosen and described so that others skilled in the art may utilize its teachings. It will be understood that no limitation of the scope of the invention is thereby intended. The invention includes any alterations and modifications in the illustrated device, the methods of operation, and further applications of the principles of the invention which would normally occur to one skilled in the art to which the invention relates. 
     With reference to  FIG. 2 , a typical small sailboat  10  is shown having a radar antenna dome  11  mounted to a pole  12  at the stern of the vessel to increase its height above the water without attaching it directly to the mast or rigging where it may interfere with or be damaged by the sails. Such poles are known in the art and are typically six to 9 feet in height, 2 or 3 inches in diameter and may be made from aluminum, stainless steel or carbon. Mounting of such poles to the deck or transom of a boat is also well known in the art and is generally accomplished by a fitting secured to the deck or transom and to which the pole end is affixed by insertion, a pin or the like. A bracket and standoff may be used to brace the pole against a deck rail or deck support strut. 
     With reference to  FIGS. 3A and 3C , a stern pole  12  as described and equipped with the present invention is depicted, looking directly astern. At or near the top of the pole  12  is mounted a radar antenna dome  11  as is commonly provided to house marine radar antennas to protect them from the elements. In accordance with the present invention, the dome  11  is mounted on a bracket or platform  14  that is pivotably mounted about an axis that is substantially parallel to the centerline of the vessel  10 . A controller  20  is provided at the base of the pole for controlling the direction and degree of pivot of platform  14  by an operator in or near the cockpit of the vessel. The term platform as used herein includes any means for mounting a radar dome  11  and may include a flat plate as depicted, a perforated plate, frame, bracket, rail or other rigid member suitable to receiving and supporting the radar dome. 
     With additional reference to  FIG. 4A , in a preferred embodiment the platform  14  is mounted directly atop the pole  12  on a pivot  16 . Pivot  16  preferably includes a series of cooperating hinge knuckles  20  affixed to both the platform  14  and pole cap  18  and joined through aligned holes by a barrel or pin  22 . A tab  29  is preferably provided at or near the lateral extremities of the platform  14  on either side of the pivot  16  to which the control system  20  is directly linked to control rotation of the platform about the pivot  16 . In an alternate embodiment ( FIG. 4B ), a control arm  26  may be provided at the lower side of the platform  14  on either side of the pivot  16  to increase the lateral distance of the tab  29  from the pivot  16  in order to gain mechanical advantage. The control arm  26  may be a single bar or rod of length greater than the width of the platform  14  positioned and fixed to the platform so as to extend laterally to both the port and starboard sides an equal distance in a generally horizontal orientation. Alternately a pair of separate control arms may be provided on either side in a horizontal or downward sloped configuration. The length of the control arms  26  is directly proportional to the mechanical advantage provided to the control system (as described below). 
     In another alternate embodiment the platform  14 , while still mounted at the distal end of the pole  12 , may be mounted fore or aft of the pole on a pivot mounted to the vertical external surface of the pole. For example, the pivot may be a horizontal shaft affixed to the pole  12  for insertion into a cooperatively formed bore in the opposing platform  14 . The bore may include a bearing or bushing to minimize rotation friction of the shaft in the bore. In such an embodiment the control arms  26  would, in addition to extending directly to beam, extend fore or aft so as to terminate to beam of the pole itself in order to align with the linkages  28 . It is preferable that the center of mass of the platform  14  and antenna be at or slightly below the rotational axis of the shaft. Fore or aft mounting of the platform  14  just below the pole cap frees the pole cap, allowing an additional stationary antenna to be mounted such as a satcom antenna or a light, camera, etc., 
     Linkages  28  join the distal ends of the control arm  26  with the controller  20  at the base of the pole  12 . Linkages  28  are preferably a flexible, non-stretching cable and more preferably marine grade high tensile 7×19 preformed stainless steel strand cable manufactured from type  302 / 304  stainless steel or other marine grade stainless steel. When made from stainless steel cable the linkage  28  is preferably 1/16″ to 3/16″ diameter and more preferably ⅛″ diameter. Linkages  28  may, in an alternate preferred embodiment, be constructed of rigid rod or bar stock which provides a level of redundancy in as much as a single bar can both push and pull the platform  14  to pivot in both directions about the pin  16 . However, the rigidity of the rod/bar construction renders it susceptible to plastic deformation (bending) if impacted without the ability to recover its shape, thereby potentially rendering the system inoperative. Linkages formed of flexible cabling avoid this drawback but lack redundancy in as much as both cable linkages are required for operation of the device. Cable linkages  28  are also significantly easier to manufacturer at custom lengths utilizing swaged end fittings such as Lifeline T Style Toggle Jaws or Tubular Lifeline Jaws by the C. Sherman Johnson Co. Inc.(East Haddam, Conn.), rigging pins or through bolts. Cable linkages are likewise easier and less expensive to ship by common carrier. 
     In a preferred embodiment utilizing cable linkages, one or more guide collar  30  may be provided along the pole to position and guide the linkages. The guide collar  30  positions a sheave or turning block  32  on both the port and starboard sides of the pole  12  and may be positioned nearer to the pole cap or to the controller depending on the geometry of the system. Where a single guide collar is provided it is preferable to position it near the midpoint of the pole such that the cable linkages form an hourglass shape. Alternately, an upper and lower guide collar may be used simultaneously. The blocks of the guide collar allow the wire linkages  28  to run in close proximity to the pole  12  below (or between) the collar(s) and to splay outward to meet the distal ends of the tabs  29 . The guide collar  30  may include a band or compression member around the pole  12  to which to affix the blocks  32 . Alternately, the blocks may be affixed directly to the pole  12  by mechanical fasteners or other means. Where the linkages are rod or bar members the guide collar and blocks are omitted and the linkages run directly from the controller  20  to the tabs  29  as in  FIG. 4A . 
     With reference to  FIGS. 3 and 5  through  8 , a controller  20  is positioned at the proximal end of the pole above the deck so as to be accessible from the deck or cockpit of the vessel. The controller  20  has a planar back plate (as will be described) that that may be mounted to the circular pole  12  by means of one or more split ring mounting brackets  97  or similar bracket adapted to provide a flat surface or area on which to mount the controller. Alternately, the back plate  52  my be formed with a concave portion for cooperative engagement with the surface of the pole  12  and directly mounted thereto by mechanical means (not visible). The back plate  52  is generally planar in form having a width approximately equal to or slightly greater than the width of the pole  12  to which it is mounted. The lateral edges of the back plate  52  are preferably truncated so as to permit the lobes of the front plate (as described below) to extend beyond the edges of the back plate. The upper and lower edges of the back plate are preferably arcuate in form and, in the case of the upper edge, extend beyond the upper edge of the front plate so as to provide an index against which to measure rotation of the front plate relative to the back plate. 
     A hole (obscured) is provided though the back plate at its approximate center though which a post  53  is secured to rotatably affix a front plate  54  to the back plate  52 . The post  53  may be threaded on its distal end and secured by a plurality of washers and a nut behind the back plate or by other mechanical means that permit relative rotation of the plates. A spacer or bushing (obscured) of nylon or other suitable material is provided between the front plate  52  and back plate  54  around the post  53  to facilitate smooth rotation of the front plate  52  and to eliminate play between the plates. A plurality of additional holes  58  serving as detent positions (as will be described) are additionally provided though the back plate  54 . Detent holes  58  are arranged in opposing arcs about the center of rotation of the front plate  52  relative to the back plate (i.e. post  53 ) and spaced at regular angular intervals. In the depicted embodiment the detent holes are provided at 15 and 30 degrees on either side of center and the index is marked to indicate such intervals. With reference to  FIG. 3B , hinge knuckles  20  are preferably formed so as to present a bearing surface  68  for contacting the pole cap  18  when the platform has been rotated 1 to 2 degrees past the maximum detent position on either side of center. Consequently, the knuckle  20  is shaped on each side to form an angle a that is 1 to 2 degrees greater than the maximum tilt of the platform or, in the depicted embodiment, 32 degrees. The contact of the bearing surface with the pole cap acts as a positive rotational stop to prevent the linkages from binding against the controller due to over rotation of the front plate. 
     The front plate  54  is generally circular in form and, as described, is rotatably affixed to the back plate  52 . A pair of lobes  60  extend laterally from the edges of front plate  54  and are provided with through holes  62  to which the linkages  28  from the control arms  26  are attached. The linkages  28  are affixed to the through holes  62  (as well as to the control arms  26 ) by a pin, fitting, screw or other means that permits rotation of the connection. Lobes  60  are angularly spaced 180° from one another and are positioned in the horizontal plane when the controller is mounted and in the neutral position such that the platform  14  is level. The front and back plates  54 ,  52  are preferably made of stainless steel, aluminum, bronze, copper-nickel alloy or combinations thereof suitable for marine use. In certain embodiments aluminum elements may be powder coated. In certain other embodiments carbon fiber or other common boat building material having suitable strength and durability characteristics may be used. 
     A fixed handle  74  is centrally mounted to the front surface of the front plate  54  and preferably positioned to be in a vertical orientation when the controller  20  is mounted and in the neutral position as depicted in  FIG. 5 . The upper and lower arms  70 ,  72  of the fixed handle project from the surface of plate and are preferably equally spaced from the center of rotation (i.e. post  53 ). A lateral member forming a grip joins the distal ends of the upper and lower arms  70 ,  72  to form the fixed handle  74 , the center of which is directly over the center of rotation such that a user can grip the fixed handle with one hand and easily rotate the front plate  54  by rotation of the wrist. The inner surfaces of the upper and lower arms  70 ,  72  are characterized by a longitudinal recess or channel which serves as a track  76  for a moveable release handle  75 . Similar to the fixed handle, the release handle  75  is made up of an upper and lower projecting arm rigidly connected by a lateral arm or release member. The upper and lower projecting arms of the release handle extend beyond the lateral member that joins them to provide a positive stop which prevents the lateral member of the release handle  75  from being drawn all the way into contact with the lateral member of the fixed handle  74  in order to avoid pinching the hand of the operator between handles during operation. The distal ends of the projecting arms of the release handle are each provided with a protruding pin  80  that extends through a cooperatively sized hole  82  through the front plate  54  at the end of the tracks  76 . Holes  82  are radially positioned an equal distance from the center of rotation such that holes  82  align with a pair of the detent holes  58  in the back plate when the front plate is rotated to the proper orientation. A spring is provided in each track  76  to bias the release handle in the down or locked position in which the pins  80  extend through the front plate  54  and into the detent holes  58  preventing rotation of the front plate  54  relative to the back plate  52 . 
     When rotation of the front plate  54  is desired the user grips the fixed handle  74  and simultaneously grips and squeezes the release handle  75 , overcoming the biasing action of the springs and lifting the pins  80  from the detent holes  58 . The user freely rotates the front plate  54  by action of the wrist via the fixed handle, releasing the release handle  75  when the front plate  54  is at or near the desired angle of rotation. The front face of the front plate  54  is preferably marked with angle indicia to visually assist in setting the proper angle. Upon release of the release handle  75  the springs again bias the pins  80  through the front plate  54  and further into the detent holes  58 . If the detent holes  58  are not aligned with the holes  82  when the release handle is released the pins  80  will run along the surface of the back plate  52  offering little resistance to rotation and will simply fall into the next available detent holes  58  upon proper alignment. 
     In an alternate embodiment a single arm extends from the front surface of the front plate  54  supporting the grip handle  74  which may be parallel to or sloped away from the surface but is preferably aligned over the center of rotation in either case as above. A release handle  75  is pivotably mounted to the front plate  54  or the grip handle  74  and affixed to a spring biased pin  80  so as to withdraw the pin from the detent holes and permit rotation of the front plate  54  relative to the back plate  52  until the release handle  75  is released at which point the spring biases the pin  80  to re-engage the detent holes. 
     In use, a radar antenna is mounted to the platform  14  which is maintained in a level position when the vessel is at rest or otherwise in an upright (not heeled) position. The pins  80  are biased into the detent holes  58  and retain the front plate  54  in a fixed position which fixes the platform  14  via the linkages  28 . Under sail, as the vessel heels over a user grips the grip handle  74  and simultaneously grasps the release handle  75  to overcome the biasing action of the springs to disengage the pins  80 . Once free of the detents, the user can easily rotate the front plate  54  by rotating his wrist. Rotation of the front plate  54  causes the antenna platform  14  to similarly rotate via the linkages  28 . When the platform  14  is leveled the user releases the release handle  75  and again secures the front plate  54  in place and likewise secures the platform  14  in place. On tacking or a change in the heel angle due to a change in course or wind conditions the user can easily and quickly adjust the platform  14  angle to re-level the antenna. 
     Having now fully set forth the preferred embodiment and certain modifications of the concept underlying the present invention, various other embodiments as well as certain variations and modifications of the embodiments herein shown and described will obviously occur to those skilled in the art upon becoming familiar with said underlying concept. It is to be understood, therefore, that the invention may be practiced otherwise than as specifically set forth in the appended claims and may be used with a variety of materials and components. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains.