Patent Publication Number: US-5898412-A

Title: Transmit/receive antenna mounting enclosure

Description:
FIELD OF THE INVENTION 
     The invention relates to a mounting enclosure for transmit and receive antennas for radio communications systems, for example, cellular communications systems. 
     SUMMARY OF THE INVENTION 
     Antenna mounting enclosures for local cellular communications systems and for combined cable and radio cell systems must meet a number of structural and functional requirements. The enclosure provides a protective enclosure for a printed circuit board and the structure for externally supporting the receive and transmit antennas that connect to the printed circuit board. The mounting enclosure is mounted on a utility pole or a cable or cross piece carried on a pole, which typically subjects it to size restriction by local government regulations. In addition, the enclosure must be adaptable to mounting vertically or horizontally, as conditions permit, while ensuring the correct orientation of the antennas. Further, the removal and replacement of antennas on the enclosure must be facilitated for field repair or replacement. In addition, the installation of a new or replacement antennas must ensure the correct placement of receive and transmit antennas, that is, that installation of a receive antenna in a transmit antenna location must be prevented, and vice versa. 
     The present invention provides a mounting enclosure for receive and transmit antennas and a printed circuit board that solves these and other problems. 
     The mounting enclosure according to the invention includes means for mounting the enclosure with a long axis oriented in the vertical or the horizontal, and includes means for mounting antennas with correct vertical antenna orientation. 
     According to another aspect of the invention, the mounting enclosure includes means for ensuring that only the compatible type of antenna is mountable at the designated mounting locations, that is, that a transmit antenna may be mounted only at a transmit antenna location. 
     According to yet another aspect of the invention, the enclosure includes a plurality of cooling fins formed on the external front and rear faces, the fins being oriented obliquely to the long axis of the enclosure to provide good air flow for cooling when the enclosure is mounted either vertically or horizontally. 
     The enclosure according to the invention also provides an enclosure in which the receive and transmit antennas are mounted so that interference between the antennas is substantially prevented. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of the front of a mounting enclosure in accordance with the invention showing a horizontal enclosure mounting arrangement; 
     FIG. 2 is a perspective view of the rear of the mounting enclosure of FIG. 1; 
     FIG. 3 is a top view of the mounting enclosure of FIG. 1; 
     FIG. 4 is an end view of the mounting enclosure of FIG. 1; 
     FIG. 5a is a front view of the enclosure showing a horizontal enclosure mounting arrangement; 
     FIG. 5b is a rear view of the enclosure of FIG. 5a; 
     FIG. 6a is a front view of the enclosure showing a vertical enclosure mounting arrangement; 
     FIG. 6b is a rear view of the enclosure of FIG. 6a; 
     FIG. 7 is a front view of the enclosure according to the invention with the antennas removed; 
     FIG. 8a is a bottom view of antenna showing a base plate; 
     FIG. 8b is an end view of the antenna of FIG. 8a; 
     FIG. 8c is a side view of the antenna of FIG. 8a; 
     FIG. 9 is a section view of the enclosure showing the connections of the antennas with a printed circuit board mounted therein; 
     FIG. 10a is a top view of a connector access seal; and 
     FIG. 10b is a side view of the connector access seal of FIG. 10a. 
    
    
     DETAILED DESCRIPTION 
     An antenna mounting enclosure 10 according to the invention is illustrated in perspective view in FIG. 1 and FIG. 2. The FIGS. 1 and 2 show a mounting arrangement for receive antennas 22, 24 and transmit antennas 26 for a horizontal enclosure orientation. An alternative vertical enclosure orientation is described and illustrated below in connection with FIG. 6a and 6b. The mounting enclosure 10 includes a front shell 30 and a rear shell 32 fastened together to enclose an interior space (shown in the sectional view of FIG. 9). The mounting enclosure 10 is preferably rectangularly shaped and has a longitudinal axis A--A which is longer than a transverse axis B--B. 
     The mounting enclosure 10 may be mounted, for example, in a horizontal orientation on a cable or strand carried by a pole, or in a vertical orientation mounted to a utility pole or other structure. Fastening holes 16 are formed in the enclosure 10 for attaching a mounting bracket (not illustrated) to the enclosure 10. Local government regulations may restrict the space available on a utility pole to a maximum vertical distance. The width of the enclosure on the transverse axis B--B is given a size to comply with the maximum allowable distance, to permit horizontal mounting of the enclosure within allowable limits. 
     The antennas 22, 24, and 26 each have an antenna axis, indicated by the broken line C, which corresponds in the illustrated antennas to the longer dimension of the antenna unit. The antenna axis C must be vertically oriented when the enclosure 10 is mounted. As shown in the horizontal enclosure orientation of FIGS. 1 and 2, the antenna axes are parallel to the transverse axis B--B of the enclosure 10. As is further described below, the enclosure 10 according to the invention provides for mounting of the antennas in the correct vertical antenna axis orientation for either enclosure orientation. 
     The enclosure 10 is preferably formed of aluminum, by casting or machining, to provide an enclosure that is light-weight, strong, and protective from environmental contaminates such as water or moisture. Aluminum is heat conductive, which facilitates removing heat from the system&#39;s electronic components. Other materials that provide suitable protection and heat conduction may alternatively be employed. The shells 30, 32 are formed with grooves ridges on their mating edges (not illustrated), and a gasket is provided to seal the edges and prevent the ingress of water or moisture. 
     The enclosure 10 includes, on both the front 30 and rear 32 shells, a plurality of cooling fins 40. The cooling fins 40 are rib-like formations that project perpendicularly from the walls of the front 30 and rear 32 shells. The fins 40 are oriented obliquely to the longitudinal A--A and transverse B--B axes. The fins 40 are provided to help dissipate heat generated by the printed circuit board and power supply. The oblique orientation, preferably at 45° to the longitudinal axis A--A, ensures a flow of air over the cooling fins 40 in either of the horizontal or vertical enclosure orientations. 
     The rear shell 32 includes connector taps 44, 46 to connect, for example, with a power source and/or a cable connection with a customer in a cable cell system. 
     The enclosure 10 also includes a sliding door 50 covering an aperture on the front shell 30 to permit field access to the interior of the enclosure without the necessity of removing the enclosure from its mounting and disassembling the shells. The door 50 is formed as a flat panel with legs 52 extending from each of the four corners. The door 50 is captured between two pins 54 for sliding movement, the legs 52 providing stops to limit movement of the door. 
     Supporting feet 60 are formed on the front shell 30 and supporting feet 62 are formed on the rear shell 32. When the shells 30, 32 are assembled as shown in FIG. 1, the feet 60, 62 form platforms that allow the enclosure 10 to stand horizontally on the long side, as shown, or as may be understood, vertically on the short side. As may be seen in FIG. 3, the feet 60, 62 are made sufficiently long to accommodate the thickness of the antennas 22, 24, and 26, to allow the enclosure 10 to stand on either the front shell 30 or the rear shell 32 without risk of damage to the antennas. The feet 60, 62 shown in the figures are formed as curved projections at the comers of the shells 30, 32. Alternatively, the feet may be formed as enlargements of the comer cooling fins of the shells 30, 32. 
     FIGS. 5a and 5b illustrate a front and rear view of the enclosure 10 with horizontal mounting orientation. The antennas 22, 24 and 26 are, as explained above, oriented with the respective axes C aligned on the transverse axis B--B of the enclosure 10. FIGS. 6a and 6b illustrate the enclosure 10 in vertical mounting orientation with the antennas 22, 24 and 26 correspondingly oriented on the longitudinal axis A--A of the enclosure 10. As may be understood from the FIGS. 5a, 5b and 6a, 6b, the transmit antennas 26 are separated from the receive antennas 22, 24 by a predetermined space. As described above, the spacing is provided to prevent interference between transmit and receive antennas. In addition, the respective transmit antennas 26 and receive antennas 22, 24 on each of the front 30 and rear 32 shells are arranged back to back across that enclosure, that is, in opposition across the interior space. This also helps insure that the various antennas do not interfere with each other. 
     In FIG. 9, a cross section of the enclosure 10 shows antennas 24 and 26 connected to the printed circuit board 90 with connectors 92. The connectors 92 are standard type coaxial connectors with spacers or adapters to provide any needed length. The printed circuit board 90 is mounted on studs 94 in the rear shell 32. The printed circuit board 90 is not rigidly attached to the studs 94, but is allowed some float to compensate for expansion and contraction of the connectors 92 due to heating and cooling during use. 
     FIG. 7 illustrates a front view of the front shell 30 with the antennas removed. The antennas are mounted to the enclosure with fasteners (not shown) screwed into a selected one of groups of threaded bosses 72a-b, 74a-b, and 70e-f formed on each of the shells. The following description of mounting and connecting means for the antennas for the front shell 30 is understood to apply as well to the rear shell 32. The groups of bosses 72a-b, 74a-b, and 70e-f are disposed on the shell face each in relation to one of the access holes 82, 84 and 80 to permit each of the antennas to connect with the printed circuit board in the enclosure 10. The groups of bosses 72a-b, 74a-b, and 70e-f are arranged to define a specific mounting location for a particular receive 22, 24 or transmit antenna 26. In addition, each group of bosses defines mounting locations for selectively mounting an antenna in either the horizontal or vertical enclosure mounting orientation. 
     The individual bosses are formed in the cooling fins 40, which creates virtually no disruption of cooling air flow between the fins, and simplifies the manufacture of the shell. 
     Referring to the bosses 72a and 72b, an antenna mounting location for the antenna 22 is defined. The bosses 72a define a mounting location for horizontal enclosure mounting orientation, and the bosses 72b define a mounting location for vertical enclosure mounting orientation. The bosses 72a and the bosses 72b both have the same positional relationship with the connector access hole 82. The boss 72ab is used in both orientations and helps simplify the design of the shell face. As may be seen, the groups of bosses 74a, 74b and 70e, 70f are similarly disposed to define horizontal and vertical orientation mounting locations at the access holes 84 and 80, respectively. 
     The access holes 82 and 84 are formed on a first collar 88 and the access hole 80 is formed on a second collar 89, spaced from the first collar 88. There are two types of receive antenna, which are unique and not interchangeable. Of course, the receive and transmit antennas are also not interchangeable. The collars 88 and 89 include mating means to ensure that only the correct type of antenna is mounted at the designated mounting location. According to the preferred embodiment, groups of keying holes 73, 75 and 77 are arranged on the collars for mating with corresponding keying pins provided on the antennas. Each of the groups of keying holes 73, 75, and 77 is arranged in a different pattern. The collar 88, 89 surfaces, therefore, will reject an antenna with an incompatible pin arrangement, thus ensuring exclusive mounting of the designated antenna. 
     FIGS. 8a, 8b, and 8c illustrate an antenna 22 in three views. The antenna 22 includes a base plate 102 and a cover 104. The base plate 102 carries keying pins 106a, b and the connector 94. The connector 94 is located at the same base plate position in all the antennas. As seen in FIGS. 80b and 8c, the pins 106 and connector 94 extend from the base plate 102 to engage the keying holes and the connector access holes in the enclosure 10. 
     Each keying pin group comprises two pins 106 positioned relative to the connector 94. One pin 106a is positioned to define with the connector 94 a first line perpendicular to the edge 108 of the base plate adjacent to the connector 94. This pin position 106a is the same for all antennas, which simplifies manufacture. The second pin 106b is positioned at a predetermined distance from the connector 94 and to define with the connector 94 a second line at a predetermined angle α from the first line. For each type of antenna, the relative position of the second pin is unique, which may include the distance from the connector and the angle at which the defined line is disposed. The corresponding key holes in the collar 88 of the enclosure 10 are positioned with a compatible relationship to the access hole 82. As may be seen in FIG. 7, two sets of keying holes are provided at each of the access holes 82, 84 and 80. The two sets are identically arranged, with one set positioned for each of the vertical and horizontal enclosure mounting orientations. 
     To simplify manufacturing, a single base plate 102 having holes for all of the alternative antenna pin arrangements may be made, and the plate for a particular antenna completed by placing the second pin in the appropriate hole. The keying means may be formed by other than the described key holes and pins, for example, by using uniquely or differently shaped pins, or other suitable rejection arrangements. 
     FIGS. 10a and 10b illustrate a sealing grommet 110 that is press fit in each of the access holes 82, 84, and 80 to prevent water or moisture from entering the interior space of the enclosure 10. The grommet 110 includes a central hole 112 through which the connector 94 is inserted. The grommet 110 is formed from an elastomeric material, and resiliently abuts the base plate 102 of the antennas to help form a seal. In addition, the grommets 110 readily adapt to small differences in connector length arising from manufacturing tolerances. 
     The invention has been described in terms of preferred features and embodiments, however, those skilled in the art will appreciate that the invention may be practiced with equivalents for the specific elements described without departing from spirit and scope of the invention as defined by the following claims.