Abstract:
A mounting means ( 1 ) for RF connectors ( 6 ) to be connected to a substrate ( 20 ) comprises a base plate ( 2 ) having an upper surface ( 2   a ) and a lower surface ( 2   b ). The base plate exhibits electrically leading material at least on part of its surfaces. Ground pads ( 3 ) are provided on the upper surface ( 2   a ) of the base plate ( 2 ) and arranged for support and electrical contacting to the substrate. A plurality of through holes ( 4 ) for electrically isolated reception of inner conductors ( 5 ) of RF connectors. By means of this mounting means, quick, secure, and space-saving mounting of RF connectors is achieved.

Description:
FIELD OF INVENTION 
     The present invention relates generally to a means for mounting RF connectors to for example a printed circuit board and more particularly to a mounting means, which facilitates mounting of RF connectors with high precision. The present invention also relates to an antenna module comprising such mounting means, and a method of mounting RF connectors. 
     BACKGROUND 
     Antenna modules for vehicles are generally attached to the roof; the antenna module housing is to this end attached to the roof by means of for example a screw connection and is connected via connectors, such as RF connectors, which generally extend through the vehicle roof and into the interior of the vehicle. 
     For the contacting of several RF connectors for more complex antenna modules exact positioning of the connectors is necessary since the performance can be adversely affected if the RF connectors are misaligned. 
     However, there is generally only a limited space available in a lateral direction for the connectors, such as a hole with the size of 15×15 or 17×17 mm, in which four connectors are to be fitted. Exact contacting and assembly are therefore often difficult to achieve. 
     SUMMARY OF THE INVENTION 
     An object of the invention is to provide a quick, secure, and/or space-saving mounting of RF connectors to a module, such as an antenna module, to ensure contacting of the RF connectors to the antenna module. 
     This object is according to a first aspect of the invention achieved by a mounting means for RF connectors according to claim  1 . According to other aspects of the invention there are provided an RF connector device according to claim  15 , an antenna module according to claim  16 , and a method of mounting RF connectors according to claim  17 . 
     The dependent claims describe further preferred embodiments. 
     The basis of the invention is to first attach one or several RF connectors to a base plate, wherein inner conductors of the connectors extend through the base plate. Thus, the base plate with one or more assigned RF connectors can thereafter be installed directly onto a substrate, such as a printed circuit board, which can take place with a standard mounting (SMD mounting) method. 
     The outer conductors of the coaxial RF connectors can be provided on and contacted directly to the lower surface of the base plate, wherein the base plate can be made of metal, so that it serves as a common ground for all connectors. The outer conductors can be provided on the frame or provided in corresponding for example socket shaped connector receiving means, which extend from the lower surface of the frame. 
     Furthermore, coding means are preferably provided to ensure safe, polarity-free mounting of the equipped frame to a printed circuit board. 
     Ground pads in the form of for example small ground legs or protrusions protrude from the upper surface of the base plate, which serve for contacting the substrate as well as taking up forces. The small ground legs thus take up the forces and bending moments influencing during assembly and loading. The small ground legs are to this end preferably provided laterally outside of the frame. Also the coding means, which in particular can be extending coding pins, serve to take up forces and bending moments to avoid or at least minimizing loading of the inner conductors of the RF connectors. 
     A substrate, such as a printed circuit board, can be equipped directly with the connector device comprising the base plate and a plurality of RF connectors and the antenna module with its antenna module housing is then attached to the printed circuit board, so that the whole can be fastened as unit to the vehicle roof. There is also the possibility of attaching the connector device to the antenna module housing if this is provided with corresponding attachment means, for example tabs for screw connections or stampings, for example. Hereby is the force application by the connection force conducted onto the antenna module housing. 
     The tolerances between the RF connectors can be kept small by the use of the base plate, so that a very space saving, narrow RF connector device is made possible. In case of using SMB connectors, for example, tolerances for the distances of the inner conductors from for example 9+/−0.02 mm can hereby be achieved. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The invention is now described, by way of example, with reference to the accompanying drawings, in which: 
         FIG. 1  a plan view of a base plate comprised in an RF connector device according to invention; 
         FIG. 2  a side view of the base plate of  FIG. 1  provided with RF connectors; 
         FIG. 3  is a bottom view of the base plate and connectors shown in  FIG. 2 ; 
         FIG. 4  a perspective view of the connector device shown in  FIGS. 1-3 ; 
         FIG. 5  is a side view of an alternative embodiment of a base plate comprised in a mounting means according to the invention; 
         FIG. 6  shows a plan view from below of an RF connector device according to the invention attached to a vehicle roof; 
         FIGS. 7-9  show sectional views of alternative embodiments of an antenna module according to the invention attached to a vehicle roof; 
         FIG. 10  shows a complement unit connectable to an RF connector device according to the invention; 
         FIG. 11  is a detailed view of an antenna module provided with an RF connector device according to the invention; 
         FIG. 12  shows the antenna module of  FIG. 11  provided with the complement of  FIG. 10 ; and 
         FIGS. 13-15  show an alternative embodiment of an RF connector device modified from the one shown in  FIGS. 1-3 . 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     In the following a detailed description of preferred embodiments of the present invention will be given. It will be realized that the directions given in this description, such as upper and lower, are intended for non-limiting explanation only and refer to the directions shown in the figures. 
     An RF connector device or frame  1  comprises in accordance with  FIGS. 1-4  a base plate  2  made of metal material having an upper surface  2   a  and a lower surface  2   b . Ground pads in the form of small metal ground legs or protrusions  3  extend from the upper surface  2   a  of the base plate  2 . These legs are preferably integral with the rest of the base plate, thus forming a unitary unit. Through holes  4  are provided in the base plate  2 , which in the shown embodiment are four symmetrically arranged holes in the corner areas of the base plate. These through holes extend from the upper surface  2   a  down to the lower surface  2   b  and are arranged to receive a respective inner conductor  5  of RF connectors  6  inserted into these through holes  4  from the lower surface of the base plate. 
     The RF connectors  6  can for example be connectors sold under the trademark FAKRA and are designed as coaxial connectors comprising a dielectric  8  and an outer conductor  10  around the inner conductor  5 . The inner conductors  5  are provided isolated through the base plate  2  and extend as shown in the side view of the  FIG. 2  to the upper surface  2   a  of the base plate, so that they there can be further contacted, as will be described below. 
     The outer conductor  10  is contacted to the frame  1 , e.g., by simply resting on or being soldered to the base plate  2 . This base plate  2  thus appears as a common ground to the outer conductors  10  of several, for example four assigned RF connectors  6 , and is also contacted through its small ground legs  3 . 
     In the shown embodiment, three ground legs  3  are provided around a through hole  4  to form a semi coaxial screen around each of the inner conductors  5  which extend through the holes  4 . 
     One or more coding pins  12  extend from the upper surface  2   a  of the base plate  2  and are arranged asymmetrically and exchange-safely, so that they enable a predetermined positioning of the base plate and prevent a 90°, 180°, or 270° rotated mounting of the equipped base plate to a substrate. 
     The base plate  2  exhibits a recess or opening, which according to the shown embodiment is provided in the center of the base plate  2 . This opening can however also be omitted in accordance with other embodiments. 
     In accordance with the alternative embodiment shown in  FIG. 5  complementary connector receiving means  15  are provided on the lower surface  2   b  of the base plate  2 , which facilitates mounting of the RF connectors  6  to the base plate  2 . A complete RF connector  6  can hereby be inserted, so that its outer conductor  10  contacts the connector mounting means  15 . The RF connectors  6  can alternatively at their ends be laid bare from their outer conductors  10 , so that the connectors  6  are inserted only with their inner conductors  5  and their dielectric into the connector receiving means  15 , whereby the connector receiving means  15  make contact with the ends of the shortened outer conductors  10  at the front side. 
     The length L of the RF connectors  6  can vary but the dimensioning of the connector device  1  can nevertheless be kept very exact, so that placement of the RF connectors  6  becomes possible with small tolerances. The base plate can for example be square shaped with a length of 17+/−3 mm, wherein the distance of the through holes  4  and thus also the assigned inner conductors  5  can be accurately provided at a mutual distance of 9+/−0.02 mm. 
     A method of mounting RF connectors will now be described with reference to  FIGS. 6-12 . First, RF connectors  6  are attached to the base plate  2  so that the respective inner conductor extends through an assigned through hole  4  in the base plate. The connector device  1  in  FIG. 1  to  FIG. 4  formed in this way by the base plate  2  and assigned connectors  6  is subsequently attached to a substrate  20 , such as a printed circuit board, see  FIG. 7 . The ground legs or protrusions  3  are thereby placed on corresponding ground means, such as ground contacts or contact pads on the lower surface of the printed circuit board  20 , preferably attached by means of solder and/or conductive adhesive, and the coding pins  12  are placed in corresponding recesses in the printed circuit board  20  and attached by means of for example a paste. The inner conductors  5  of the connectors  6  are contacted to the printed circuit board  20  with corresponding connections by means of soldering, for example. The inner conductors  5  preferably have a length so that they extend through the printed circuit board  20  to the upper surface thereof, where they can be contacted. 
     Thus there is provided a positioning of several connectors  6  on the printed circuit board  20 , which is compact, very exact and with small tolerances. The connectors  6  are hereby provided directly to the base plate  2  and the complete equipped connector device  1  is subsequently provided on the printed circuit board  20 , which preferably take place in an SMD mounting process. 
     In accordance with  FIGS. 7-9  the printed circuit board  20  is attached to an antenna module chassis  22 , so that an entire module  23  of the parts  2 ,  6 ,  20 , and  22  can be attached to a vehicle roof  24  by means of for example an attachment bolt  25 , see  FIG. 7  or  8 , or a bolt  27  (shown in  FIG. 10 ) inserted into a threaded hole  26  in the chassis  22 , see  FIG. 9 . In order to keep dimensions small, the bolt is preferably of the dimension M 5  or M 6 , attached with a torque of about 2.5-3.0 Nm. The RF connectors  6  hereby extend through a corresponding hole in the vehicle roof  24  and can be contacted from below. 
     The small ground legs  3  and the coding pins  12  take according to invention up the arising forces and bending moments, so that loading of the inner conductors  5  is avoided or at least minimized. 
     A complementary unit  28  will now be described with reference to  FIG. 10 . This unit comprises a housing or bracket  29  which encloses a plurality of RF couplers  30 , wherein each of the RF couplers is arranged to connect to a corresponding one of the plurality of RF connectors  6  on the connector device  1 . The RF couplers  30  are connected to an RF harness cable  31 , which connects the antenna module to the electronics of the vehicle to which the antenna module is attached. 
     The bracket  29  is provided with a snap-in  32  arranged to cooperate with a snap nose provided on a mounting clip, as will be described below with reference to  FIG. 11 . 
     The complementary unit  28  finally comprises a bracket metal sheet  33  for grounding purposes. 
     Turning now to  FIG. 11 , the antenna module chassis  22  is provided with a clip  33  of electrically non-conducting material, such as plastic, which is used for pre-fixation of the antenna module on the vehicle roof  24 . This is achieved by means of a snap nose  34 , which is part of the clip  33 . The snap nose also functions as a coding during mounting of the complement unit to the antenna module. This means that the snap nose  34  and the snap  32  of the complement unit must be aligned in order to attach the complement unit, eliminating the risk of incorrect rotation of the complement unit. 
     Thus, the method of mounting the antenna module comprises attaching the printed circuit board  20  to the chassis  22  of the antenna module, where after the antenna module housing is attached. The antenna module is then placed on the vehicle roof so that the connectors  6  are aligned with the hole in the vehicle roof. This is preferably achieved by means of the pre-fixation clip  33 . The mounting procedure is completed by attaching the complement unit  28  to the antenna module by means of the screw  27 . 
     In  FIG. 12 , the entire antenna module  23  is shown with the attached complement unit  28 . The vehicle roof to which the antenna module is to be attached is omitted for clarity. 
       FIGS. 13-15  show an alternative embodiment, wherein the base plate  2  shown in  FIG. 1  to  FIG. 3  has been modified by the addition of tabs or tongues  35 , through which the force application can be diverted also directly into the antenna module housing  22 . The tabs  30  can for this extend laterally. 
     The base plate  2  can be made completely of metal, for example as a pressure casting part from brass with galvanization, or from steel or aluminum. Alternatively part of or the entire surface of the base plate is electrically conductive and the interior is made of some suitable electrically non-conductive material, such as plastic. 
     Preferred embodiments of a mounting means, an RF connector device, and an antenna module have been described. It will be appreciated that these embodiments can be modified without departing from the inventive idea as defined by the appended claims. Thus, each base plate can hold fewer or more than four connectors, depending on the application. 
     The ground pads on the base plate have been described as small legs extending from the upper surface of the base plate. It will be appreciated that these ground pads can take other shapes and can for example be flush with the upper surface of the base plate. 
     In the described antenna module, the connectors  6  are RF connectors adapted to transmit signals in the radio frequency range. It will be appreciated that the inventive idea is applicable to any kind of connector and particularly connector arrangements wherein the demands on mounting tolerances are strict. 
     An antenna module arranged for mounting to a vehicle has been described. It will be appreciated that the inventive idea is applicable to any antenna module, such as antenna modules intended for indoor mounting.