Abstract:
A radio frequency transceiver having a printed circuit board (PCB) on which are located a plurality of components, the PCB being sandwiched between a base and a cover. The cover having a plurality of components for accommodating each of the plurality of components to separate the plurality of components into a number of virtual modules. All interconnects between the number of virtual modules are in the PCB. The PCB has a radio frequency (RF) layer, a RF ground layer, a direct current (DC) layer, and a DC ground layer. There is a plurality of via holes from the RF ground layer to the DC ground layer to provide virtual RF ground.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to radio frequency transceivers and refers particularly, though not exclusively, to radio frequency transceiver constructed using a virtual modular arrangement.  
       BACKGROUND TO THE INVENTION  
       [0002]     Present radio frequency transceivers are constructed using several separate modules each having a required electrical function. Each module is securely mounted in a housing (a large box) and the modules are interconnected as required using wires, cables, and so forth. This involves considerable labour, and results in a housing that is relatively large. Many interconnects are required.  
         [0003]     It is therefore a principal object of the present invention to provide a radio frequency transceiver where interconnects between modules are generally not required.  
         [0004]     A further object of the present invention is to provide a radio frequency transceiver where virtual modules are used.  
         [0005]     Another object of the resent invention is to provide a radio frequency transceiver where the construction aids heat dissipation.  
         [0006]     A final object of the present invention is to provide a multi-layer printed circuit board for use with such a radio frequency transceiver.  
       SUMMARY OF THE INVENTION  
       [0007]     With the above and other objects in mind, the present invention provides a radio frequency transceiver having a printed circuit board on which are located a plurality of components, the printed circuit board being sandwiched between a base and a cover, the cover having a plurality of means for accommodating each of the plurality of components to separate the plurality of components into a number of virtual modules.  
         [0008]     All interconnects between the number of virtual modules are preferably in the printed circuit board.  
         [0009]     Both the base and the cover may be made of a heat conductive material so that at least one of the base and the cover may act as a heat sink.  
         [0010]     Each of the means for accommodating may be a compartment in a lower surface of the cover. Each compartment may recess into lower surface of the cover, and each recess may be of a depth sufficient to accommodate the component to be located therein. One of the recesses pass may completely through the cover.  
         [0011]     The compartments may be formed by pathways projecting downwardly from the lower surface of the cover, the pathways forming the compartments therebetween.  
         [0012]     The cover may include a plurality of pathways for aligning with a plurality of DC pathways in the printed circuit board. The plurality of pathways may extend downwardly from the cover.  
         [0013]     The printed circuit board may include a radio frequency layer, a radio frequency ground layer, a DC layer, and a DC ground layer. There may be a plurality via holes from the radio frequency ground layer to the DC ground layer to provide virtual radio frequency ground.  
         [0014]     The plurality of components may includes one or more of down converter, reference oscillator, at least one band pass filter, C-band synthesizer, at least one up converter, and at least one L-band synthesizer.  
         [0015]     The DC layer may include the DC pathways to provide power connections to all the virtual modules; and each compartment may be of dimensions to substantially eliminate higher order modes of signal propagation. Furthermore, and more preferably, radio frequency radiation for each virtual module is contained within that virtual module. Each virtual module preferably comprises one means for accommodating and at least one component.  
         [0016]     The base may provide a radio frequency ground; and the DC layer may include a pattern of a plurality of fans that, in combination with the DC ground layer and radio frequency ground layer, form capacitors to filter radio frequency signals to ground.  
         [0017]     In another form, the present invention provides a radio frequency transceiver having a printed circuit board on which are mounted a plurality of components comprising the radio frequency transceiver and a cover; the cover including a lower surface with means for separating the cover into at least two compartments, each compartment for receiving therein at least one of the plurality of components to create at least two virtual modules.  
         [0018]     In a final form the present invention provides a printed circuit board for use with a radio frequency transceiver wherein the printed circuit board has a radio frequency layer, a radio frequency ground layer, a DC layer, and a DC ground layer. There may be a plurality via holes from the radio frequency ground layer to the DC ground layer to provide virtual radio frequency ground. The base may provide a radio frequency ground; and the DC layer may include a pattern of a plurality of fans that, in combination with the DC ground layer and radio frequency ground layer, form capacitors to filter radio frequency signals to ground. The DC layer may include a plurality of DC pathways to provide power connections to a plurality of components mountable on the printed circuit board, the plurality of components being arranged as a number of virtual modules. 
     
    
     DESCRIPTION OF THE DRAWINGS  
       [0019]     In order that the invention may be clearly understood and readily put into practical effect there shall now be described by way on non-limitative example only a preferred embodiment of the present invention, the description being with reference to the accompanying illustrative drawings in which:  
         [0020]      FIG. 1  is a perspective view of the preferred embodiment removed from the housing (not shown);  
         [0021]      FIG. 2  is an underneath view of the cover of  FIG. 1 ;  
         [0022]      FIG. 3  is a side view of the printed circuit board of  FIG. 1 ;  
         [0023]      FIG. 4  is a top plan view of the cover and the printed circuit board and the cover, the top plate of the cover having been removed;  
         [0024]      FIG. 5  is a plan view of the printed circuit board showing the connection between the modules; and  
         [0025]      FIG. 6  is a top plan view of the base. 
     
    
     DESCRIPTION OF PREFERRED EMBODIMENT  
       [0026]     To first consider  FIG. 1 , there is shown a radio frequency transceiver removed from its housing (not shown) and having a cover  10 , a printed circuit board  12  and a base  14 . The cover  10  and base  14  “sandwich” the printed circuit between them.  
         [0027]     Base  14  ( FIG. 6 ), is generally planar and has a top surface that is flat. Preferably, base  14  is made of a heat-conductive material such as, for example, aluminium so that it will aid heat dissipation from the various components mounted on the printed circuit board. By using aluminium the overall weight is also reduced. Effectively, the base  14  acts as a heat sink and acts as a support for the printed circuit board  12 . It also provides a radio frequency ground. The shape of the base  14  closely follows the shape of both the printed circuit board  12  and the cover  10 . The base  14  may be secured to cover  10  using screws, nuts and bolts, clips, or other readily releasable yet secure fastening.  
         [0028]     To now refer to  FIG. 2 , the cover  10  is also generally planar and has a generally flat top  20 . Cover  10  also has a plurality of pathways  16  and compartments  18 . The compartments  18  are sized, shaped and located to align, preferably align exactly (within reasonable manufacturing tolerances) with components mounted on the printed circuit board  12 . The compartments  18  may be in the form of concave recesses into the lower surface of cover  10 , with each compartment  18  being recessed to a sufficient extent to accommodate the components on printed circuit board  12  to be located therein. Alternatively, the compartments  18  may be formed by pathways  16  projecting downwardly to from compartments  18  therebetween. Each compartment  18  may be recessed differently to accommodate its components, or all compartments  18  may be recessed to the same depth.  
         [0029]     The pathways  16  are sized, shaped and located to align exactly (within reasonable manufacturing tolerances) with the DC pathways of the printed circuit board  12 . The radio frequency signal travels along the pathways  16  from one compartment  18  to another compartment  18 .  
         [0030]     In this way, the combination of the pathways  16  and compartments  18 , in combination with components mounted on printed circuit board  12 , create virtual modules on printed circuit board  12 , and in cover  10 . As such, any radiation is kept within each virtual module and, as such, should not interfere with other virtual modules. Preferably, by controlling the dimensions of each compartment  18 , higher order modes of signal propagation may be eliminated.  
         [0031]     Like base  14 , cover  10  may be made of a heat conductive material such as, for example, aluminium. In this way it aids heat dissipation from the components on printed circuit board  12 . This means that, in effect, the cover  10  is also acting as a heat sink.  
         [0032]     If desired, and particularly for components on printed circuit board of greater height, one or more of the compartments  18  may pass through top  20 , as is shown in FIG  1 . The shape of the cover  10  closely follows the shape of both the printed circuit board  12  and base  14 . The cover  10  may be releasably secured to the base  10  by use of one or more of screws, nuts and bolts, dips, or other readily releasable yet secure fastening. Holes  22  through cover  10  may be provided to assist this.  
         [0033]      FIG. 3  shows the construction of the printed circuit board  12 . It has four layers: a radio frequency layer (top)  24 , a radio frequency ground layer (second top)  26 , a DC layer (second bottom)  28 , and a DC ground layer (bottom)  30 .  
         [0034]     The DC ground layer  30  is connected to the radio frequency ground  26  by a plurality of via holes, thus producing a virtual radio frequency ground. By doing this it is possible to maintain the same radio frequency potential through the radio frequency transceiver at the radio frequency ground  26 , base  14 , and cover  10 .  
         [0035]     The radio frequency layer  24  and the radio frequency ground  26  form the micro-strip transmission for the radio frequency circuits. Between the radio frequency layer  24  and the radio frequency ground  25  is a dielectric layer (not shown). This may be FR- 4  as using FR- 4  as a base material may decrease manufactured cost. The thickness of the dielectric layer determines the 50-ohm transmission line width.  
         [0036]     The printed circuit board as shown in  FIG. 4  has a number of components mounted thereon including, but not being limited to: down converter  32 , a reference oscillator  34  two band pass filters  36 , C-band synthesizer  38 , two low band pass filters  40 , two up converters  42 , and two L-band synthesizers  44 . There maybe LNB RF in and out terminals  46 ,  48  respectively; an output connect  50  for the power amplifies; and 70 MHz IF in and out connectors  52 ,  54  respectively.  
         [0037]     Each of the components on printed circuit board is able to be located in a compartment  18  in cover  10 . For example, each band pass filter  36  locates in a compartment  56 ; C-band synthesizer  38  in compartment  58 ; each L-band synthesizer  44  in a compartment  60 ; oscillator  34  in compartment  62 ; and so forth. Although it is preferred for there to be only one component for each compartment  18 , there may be more than one component (e.g. two or three) in a single compartment  18 .  
         [0038]     All components on the printed circuit board  12  are connected, preferably using 50-ohm traces. This eliminates the connection of components by interconnects, as in the past.  
         [0039]     The pathways  16  are sized, shaped and located to align exactly (within reasonable manufacturing tolerances) with the DC pathways  66 , as show in  FIG. 5 . The DC pathways  66  are in the DC layer  28 . Besides functioning as the DC power connection to all the virtual modules, the DC pathways  66  serve to control and monitor the virtual modules. Each virtual module is a combination of a component on printed circuit board  12  and its relevant compartment  18 ; and the virtual modules are separated by pathways  16 .  
         [0040]     The DC layer  28  preferably has a pattern of “fans”  64  that, in combination with the DC ground layer  30  and radio frequency ground layer  26 , form capacitors to filter the radio frequency signals to the ground (i.e. base  14 ) so that interference between virtual modules will be minimized. This, together with the virtual modules formed by the combination of the components on printed circuit board  12  and their respective compartments  18 , reduces the interference between the virtual modules.  
         [0041]     Whilst there has been described in the foregoing description a preferred embodiment of the present invention, it will be understood by those skilled it the technology that many variations in details of design or construction may be made without departing from the present invention.  
         [0042]     The present invention extends to all features disclosed both individually, and in all possible permutations and combinations.