Abstract:
A high frequency amplifier network is provided in which an auxiliary amplifier is available to replace one of a plurality of primary amplifiers. Alternately, the auxiliary amplifier may operate in parallel with one of a plurality of primary amplifiers.

Description:
PRIORITY CLAIM 
   This application claims priority to U.S. Provisional Application 60/476,599, filed Jun. 6, 2003. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to amplifier networks used in high frequency communication systems such as cellular communication systems. 
   2. Description of Prior Art 
   In communication systems, high frequency signals often require an increase in magnitude. This increase can be achieved by adding amplifiers designed for this purpose. These amplifiers are placed in series with the path of the signal. Two conditions that can affect the operation of the system employing these amplifiers are amplifier failure and the amplifier reaching its capacity limit. 
   An exemplary system employing high frequency amplification is a multi-sector cell within a cellular communication system. The most popular implementation of this type of system divides the cell into three sectors. These sectors are treated as independent paths for data traffic to follow. Data intended for radiation into the first sector is delivered to a first antenna through a first amplifier. Similarly, for paths  2  and  3 , data intended for radiation into the second (third) sector is delivered to a second (third) antenna through a second (third) amplifier. The first, second and third amplifiers are also called Primary Amplifiers. In this system, if the first amplifier fails, the data cannot be delivered to the first antenna. The same is true for failure of the second amplifier or third amplifier, in the second and third paths, respectively. 
   A well known solution to this problem of an amplifier failure is to add an additional amplifier to the system. This amplifier is called an Auxiliary Amplifier. Such a network will be designed to allow the Auxiliary Amplifier to be switched into the position of any of the Primary Amplifiers while simultaneously switching out that primary amplifier. When a Primary Amplifier failure is detected, a command is sent to the network to switch in the Auxiliary Amplifier. 
   In one specific method of this solution of protecting against amplifier failure, a divider is used to split a signal into at least two paths, and a combiner to combine the at least two paths into a single transmission line. According to this method, each path has a primary amplifier, and each path has an auxiliary amplifier. The input to each auxiliary amplifier is normally shunted to ground through a switch, but in case a primary amplifier fails, the switch can be activated to shunt the failed amplifier&#39;s input to ground, which activates the auxiliary amplifier. 
   According to this method, multiple paths may be used to limit the effect of amplifier failure in any one path, but each auxiliary amplifier is associated with only one primary amplifier. Thus, a single auxiliary amplifier provides redundancy to only one primary amplifier and one signal path. Given the service reliability of amplifiers, it is inefficient to provide an auxiliary amplifier for each primary amplifier. In addition, it is occasionally useful to increase the amplifier capacity for a specific path by employing both a primary and auxiliary amplifier. This method does not allow the primary and auxiliary amplifiers to be employed together. 
   What is needed is an auxiliary amplifier circuit in which a single auxiliary amplifier can be switched to provide redundancy for a plurality of primary amplifiers. 
   What is also needed is an auxiliary amplifier circuit in which an auxiliary amplifier can cooperate with a primary amplifier to increase amplifier capacity for a circuit path. 
   OBJECTS AND ADVANTAGES 
   It is therefore an object and advantage of the present invention to provide an auxiliary amplifier circuit in which one auxiliary amplifier can be switched into a circuit to provide redundancy for one or more primary amplifiers. 
   It is therefore a further object and advantage of the present invention to provide an auxiliary amplifier circuit in which an auxiliary amplifier can cooperate with a primary amplifier to increase amplifier capacity for a circuit path. 
   SUMMARY OF THE INVENTION 
   In accordance with the foregoing objects and advantages, the present invention provides a high frequency amplifier network in which an auxiliary amplifier is available to replace one of a plurality of primary amplifiers. Alternately, the auxiliary amplifier may operate in parallel with one of a plurality of primary amplifiers. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will be more fully understood and appreciated by reading the following Detailed Description in conjunction with the accompanying drawings, in which: 
       FIG. 1  is a schematic of the invention according to a first embodiment; 
       FIG. 2  is a schematic of the invention according to a second embodiment; and 
       FIG. 3  is a schematic of a detail of the circuit according to the second embodiment. 
   

   DETAILED DESCRIPTION 
   A network according to a first embodiment of the invention is referred to as an “N+1” network or “N+1 Cold Standby”. Here, “Cold Standby” refers to the normal status of the Auxiliary Amplifier (cold meaning not operating) and “N+1” refers to the number of amplifiers required (N is the number of primary amplifiers). This system requires one more amplifier than would be required without this network. 
   In systems where the data traffic changes over time and from sector-to-sector, it would be beneficial to have the ability to increase the amplifier capacity in any one sector at any given time. Now that the Auxiliary amplifier has been introduced into the system, a second (different) network can be designed to switch this Auxiliary Amplifier into the system not only in place of any Primary Amplifier but also in parallel with any one of the Primary Amplifiers. The amplifier capacity of any single path, will be increased, by having two amplifiers in parallel in that path. This network will provide redundancy and capacity enhancement. 
   A network with parallel auxiliary amplifier capability is referred to as an “N+1 Hot Standby” network. Here, “Hot Standby” refers to the ability to use the Auxiliary Amplifier even when all of the Primary Amplifiers are operating correctly. “N+1” still refers to the number of amplifiers required (N is the number of primary amplifiers). Again, this system requires one more amplifier than would be required without this network. 
   Both of these circuits are relatively narrow band solutions to these networks. However, the bandwidth achieved is more than adequate for the targeted cellular/wireless communications bands of interest (normally less than 60 MHz wide in the 800 MHz and 2000 MHz regions). 
   Referring now to the drawings, wherein like reference numerals refer to like parts throughout, there is seen in  FIG. 1  an auxiliary amplifier network  100  according to a first embodiment of the invention, comprising primary amplifiers  112 ,  113 ,  113 , an auxiliary amplifier  115 , input network  110  and output network  111 . Input network  110  comprises a plurality of network input ports  120 ,  122 ,  124 , input shunt switches  130 ,  132 ,  134 ,  140 ,  142 ,  144 , auxiliary amplifier input port  150 , and a plurality of transmission lines  152 . Output network  111  comprises a plurality of network output ports  125 ,  127 ,  129 , output shunt switches  135 ,  137 ,  139 ,  145 ,  147 ,  149 , auxiliary amplifier output port  151 , and a plurality of transmission lines  152 . For illustrative purposes only,  FIG. 1  depicts an auxiliary amplifier network having three primary amplifiers. The present invention, however, is not limited to a specific number of amplifiers as its principles are applicable to auxiliary amplifier networks having at least one primary amplifier. 
   Input network  110  and output network  111  are schematically the same and are mirrored around the amplifiers  112 ,  113 ,  114 . Like hardware could be used for both input network  110  and output network  111 . Those skilled in the art will recognize that the output network  111  will be required to handle more power which may higher rated components than would be necessary for the input network  110 . 
   There are four conditions of operation, which are detailed as follows. 
   In condition 1 (Normal Operation), data for sector  1  is applied to network input port  120 , amplified by primary amplifier  112  and delivered to network output port  125 . Data for sector  2  is applied to network input port  122 , amplified by primary amplifier  113  and delivered to network output port  127 . Data for sector  3  is applied to network input port  124 , amplified by primary amplifier  114  and delivered to network output port  129 . 
   On the input side, input shunt switches  130 ,  132  and  134  are all open allowing a direct 50Ω path from the network input ports  120 ,  122   124  to primary amplifiers  112 ,  113 ,  114 , respectively. Input shunt switches  140 ,  142  and  144  are all closed (shorted to ground) which presents an open at each of the network input ports  120 ,  122 ,  124  and at the auxiliary amplifier input port  150 . The open is due to the transformation through the λ/4 length of transmission lines  152  between the input shunt switches  140 ,  142  and  144  and their respective input ports  120 ,  122 ,  124 . 
   On the output side, output shunt switches  135 ,  137  and  139  are all open, providing a direct 50Ω path from the output of each primary amplifier  112 ,  113 ,  114  to the respective network output ports  125 ,  127 ,  129 . Output shunt switches  145 ,  147  and  149  are all closed (shorted to ground) which presents an open at each of the network output ports  125 ,  127 ,  129  and at the Auxiliary Amplifier output port  151 . Again, the open is due to the transformation through the λ/4 length of transmission lines  152  between the output shunt switches  145 , 147 ,  149  and the network output ports  125 ,  127 ,  129 . 
   In Condition 2 (Auxiliary Amplifier  115  Replaces Primary Amplifier  112 ), data for Sector  1  is still applied to network input port  120  and delivered to network output port  125  but is redirected through the Auxiliary Amplifier  115 . In this case input shunt switch  130  is closed (shorted to ground) presenting an open at network input port  120  and isolating the input of Primary Amplifier  112  from the network. At the same time input shunt switch  140  is opened providing a 50Ω path between network input port  120  and the Auxiliary Amplifier input port  150 . Input shunt switches  132  and  134  are open and input shunt switches  142  and  144  are closed (shorted to ground), which will present opens at network input ports  122  and  124  as well as at the Auxiliary Amplifier input port  150 . Data for sectors  2  and  3  continues in the Normal mode as described above. 
   On the output side, output shunt switch  135  is also closed, presenting an open at network output port  125  and isolating the output of Primary Amplifier  112  from the network. Output shunt switch  145  is opened, providing a 50Ω path between the Auxiliary Amplifier output port  151  and network output port  125 . Output shunt switches  137  and  139  are open and output shunt switches  147  and  149  are closed (shorted to ground), which will present opens at network output ports  127  and  129  as well as at the Auxiliary Amplifier output port  151 . 
   In Condition 3(Auxiliary Amplifier  115  Replaces Primary Amplifier  113 ) data for Sector  2  is still applied to network input port  122  and delivered to network output port  127  but is redirected through the Auxiliary Amplifier  115 . In this case input shunt switch  132  is closed (shorted to ground), presenting an open at network input port  122  and isolating the input of Primary Amplifier  113  from the network. At the same time input shunt switch  142  is opened providing a 50Ω path between network input port  122  and the Auxiliary Amplifier input port  150 . Input shunt switches  130  and  134  are open and input shunt switches  140  and  144  are closed (shorted to ground), which will present opens at network input ports  120  and  124  as well as at the Auxiliary Amplifier input port  150 . Data for sectors  1  and  3  continues in the Normal mode as described above. 
   On the output side, output shunt switch  137  is also closed presenting an open at network output port  127  and isolating the output of Primary Amplifier  113  from the network. output shunt switch  147  is opened providing a 50Ω path between the Auxiliary Amplifier output port  151  and network output port  127 . Output shunt switches  135  and  139  are open and output shunt switches  145  and  149  are closed (shorted to ground), which will present opens at network output ports  125  and  129  as well as at the Auxiliary Amplifier output port  151 . 
   In Condition 4 (Auxiliary Amplifier  115  Replaces Primary Amplifier  114 ), data for Sector  3  is still applied to network input port  124  and delivered to network output port  129  but is redirected through the Auxiliary Amplifier  115 . In this case input shunt switch  134  is closed (shorted to ground) presenting an open at network input port  124  and isolating the input of Primary Amplifier  114  from the network. At the same time input shunt switch  144  is opened providing a 50Ω path between network input port  124  and the Auxiliary Amplifier input port  150 . Input shunt switches  130  and  132  are open and input shunt switches  140  and  142  are closed (shorted to ground), which will present opens at network input ports  120  and  122  as well as at the Auxiliary Amplifier input port  150 . Data for sectors  1  and  2  continues in the Normal mode as described above. 
   On the output side, output shunt switch  139  is also closed, presenting an open at network output port  129  and isolating the output of Primary Amplifier  114  from the network. Output shunt switch  149  is opened providing a 50Ω path between the Auxiliary Amplifier output port  151  and network output port  129 . Output shunt switches  135  and  137  are open and output shunt switches  145  and  147  are closed (shorted to ground), which will present opens at network output ports  125  and  127  as well as at the Auxiliary Amplifier output port  151 . 
   This network is made up of a plurality of 50Ω transmission lines with specific electrical lengths and switches providing ground at specific locations along the transmission lines. When closed, the switches are always shunted (to ground) and never in series with the transmission lines. This proves beneficial for both electrical performance (i.e. insertion loss) and for ease in implementation. 
   Impedance and electrical lengths as well as the quality of the short circuit connection provided by each shunt switch must be controlled to provide good system impedance match. 
   Minimum insertion loss is paramount mainly in the output network  111 . This will help system efficiency as well thermal issues due to power dissipation. 
   It is undesirable for data intended for any one sector to be present at the output port for any other sector. It is primarily the quality of grounding at the shunt switches that influences this parameter. It is therefore necessary to isolate these switches by proper grounding. 
   It can be seen in  FIG. 1  that the electrical lengths of the paths through the primary amplifiers  112 ,  113 ,  114  are all equal. The electrical length, however, of the path through the auxiliary amplifier  115  is longer due to the extra transmission line required in this path. In most cases it is not a problem to have different path lengths. But there are some cases in which it may be necessary to have all path lengths equal. In these cases extra transmission line segments  152  could be added to the paths through the primary amplifiers to make up for the extra path length in the auxiliary amplifier path. When phase matching is not required, length should not be added as it will only add insertion loss. 
   The schematic in  FIG. 1  shows that the “N+1 Cold Standby” circuit can be achieved very simply with 50Ω transmission lines and shunt switches. This circuit could be built using coaxial cable, printed microstrip, printed stripline, waveguide or any other transmission line architecture. 
   In another embodiment, the invention provides a circuit for N+1 hot standby. The schematic diagram of such a circuit, which will offer redundancy and capacity enhancement in a multi-amplifier system is shown in  FIG. 2 . This capacity enhancement will be achieved by placing the Auxiliary Amplifier  215  in parallel with any one of the primary amplifiers  212 ,  213 ,  214  (assuming that the Auxiliary Amplifier  215  is not replacing one of the Primary Amplifiers  212 ,  213 ,  214  due to a failure). Again, the input network  210  and output network  211  are schematically the same and are mirrored around the amplifiers. The same hardware could be used for both networks, however the output network  211  will be required to handle more power, which may require components of higher capacity than will be necessary for the input network  210 . Input network  210  comprises comprises a plurality of network input ports  220 ,  222 ,  224 , input shunt switches  230 ,  232 ,  234 ,  240 ,  242 ,  244 , auxiliary amplifier input port  250 , a plurality of transmission lines  252 , and switchable transmission lines  262 ,  264 ,  266 ,  272 ,  274 ,  276 , each comprising two control ports  280 . Output network  211  comprises a plurality of network output ports  225 ,  227 ,  229 , output shunt switches  235 ,  237 ,  239 ,  245 ,  247 ,  249 , auxiliary amplifier output port  251 , a plurality of transmission lines  252 , and switchable transmission lines  265 ,  267 ,  269 ,  275 ,  277 ,  279 , each comprising two control ports  280 . For illustrative purposes only,  FIG. 2  depicts an auxiliary amplifier network having three primary amplifiers. The present invention, however, is not limited to a specific number of amplifiers as its principles are applicable to auxiliary amplifier networks having at least one primary amplifier. 
     FIG. 2  shows a “N+1 Hot Standby” circuit comprised of transmission line segments and shunt switches. In this embodiment, however, some of the transmission lines will have to change between two different impedances for optimal performance (a compromise could be made where some other impedance between the two desired impedances is selected, such as the geometric mean, and performance degradation due to this non-ideal condition is accepted). The preferred approach uses coupled line technology as a means of providing switchable impedances. Any realization of backward wave couplers could be applied to this circuit although microstrip and stripline seem to be the best implementation. 
   This circuit according to this embodiment requires lengths of switchable transmission line that have the ability to change impedance between 50Ω and 70.7Ω to facilitate the 2-way splitting and combining functions. These are the functions required in order to place the Auxiliary Amplifier in parallel with one of the Primary Amplifiers. This “impedance changing” function will be achieved using coupled line circuits  300  ( FIGS. 3A ,  3 B), which act as a λ/4 transmission line that can change impedance when two of the four ports (the control ports  302 ) are either shorted to ground or left open. 
   A coupled line structure with the control ports  302  terminated in open circuits ( FIG. 3A ) and another coupled line structure with the control ports terminated in short circuits ( FIG. 3B ) are introduced. The “control ports”  302  will always be either shorted to ground or left open. The two remaining ports of each coupler will make up two port networks. Each of these two port networks acts as a piece of transmission line with length θ and impedance Z i  (where the “i” stands for image—this is known as the image impedance). 
   A pair of coupled lines  304 ,  306  configured as in  FIGS. 3A and 3B  will act as a piece of transmission line that can take on two different values of characteristic impedance simply by switching between opens and shorts at the control ports  302 . It is known from coupler theory that Zoe←Zoo. When they are equal, their normalized values are both 1 and no coupling exists. Therefore, Zi open  =Zi short . It can be shown that for all other cases, where Zoe ∃ Zoo, Zi open  will be higher than Zi short  . 
   The two required impedances are 50.00Ω and 70.71Ω. Set Zi open =70.71 and Zi short =50.00Ω. This yields two equations and two unknowns. Solve for Zoe and Zoo, the values required to produce the couplers, as follows: 
   
     
       
         
           
             
               
                 
                   
                     
                       
                         Zi 
                         open 
                       
                       = 
                       
                         70.71 
                         = 
                         
                           
                             Zoe 
                             + 
                             Zoo 
                           
                           2 
                         
                       
                     
                   
                   
                     
                         
                     
                   
                   
                     
                         
                     
                   
                   
                     
                       
                         So 
                         ⁢ 
                         
                           : 
                         
                         ⁢ 
                         
                             
                         
                         ⁢ 
                         Zoe 
                       
                       = 
                       
                         141.42 
                         - 
                         Zoo 
                       
                     
                   
                 
               
             
           
           
             
               
                 
                   Zi 
                   short 
                 
                 = 
                 50.00 
               
             
           
           
             
               
                 
                     
                 
                 ⁢ 
                 
                   = 
                   
                     
                       2 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       Zoe 
                       ⁢ 
                       
                           
                       
                       ⁢ 
                       Zoo 
                     
                     
                       Zoe 
                       + 
                       Zoo 
                     
                   
                 
               
             
           
           
             
               
                 
                     
                 
                 ⁢ 
                 
                   = 
                   
                     
                       2 
                       ⁢ 
                       
                         ( 
                         
                           141.42 
                           - 
                           Zoo 
                         
                         ) 
                       
                       ⁢ 
                       Zoo 
                     
                     
                       
                         ( 
                         
                           141.42 
                           - 
                           Zoo 
                         
                         ) 
                       
                       + 
                       Zoo 
                     
                   
                 
               
             
           
           
             
               
                 
                     
                 
                 ⁢ 
                 
                   = 
                   
                     
                       
                         282.84 
                         ⁢ 
                         
                             
                         
                         ⁢ 
                         Zoo 
                       
                       - 
                       
                         2 
                         ⁢ 
                         
                           
                             ( 
                             Zoo 
                             ) 
                           
                           2 
                         
                       
                     
                     141.42 
                   
                 
               
             
           
         
       
     
       
       
         
           rearranging:
 
0=2(Zoo) 2 −282.84(Zoo)+(141.42.50)
 
           Solving this quadratic: 
         
       
     
  
   
     
       
         
           
             
               - 
               
                 ( 
                 
                   - 
                   282.84 
                 
                 ) 
               
             
             ± 
             
               
                 
                   
                     ( 
                     
                       - 
                       282.84 
                     
                     ) 
                   
                   2 
                 
                 - 
                 
                   ( 
                   
                     4 
                     × 
                     2 
                     × 
                     
                       ( 
                       
                         141.42 
                         × 
                         50 
                       
                       ) 
                     
                   
                   ) 
                 
               
             
           
           
             2 
             × 
             2 
           
         
       
     
   
   The two solutions to this quadratic equation are the even and odd mode impedances required to produce the coupler:
         Zoe=108.98Ω, Zoo=32.44Ω   Which results in: Cplg=5.3 dB, Z0=59.5Ω       

   If a coupler is built to the above parameters, it will act as a piece of transmission line that is λ/4 long and has an impedance of 50Ω when the two control ports  302  are short circuited and 70.7Ω when the two control ports  302  are open circuited. 
   With this switchable impedance function available, the desired circuit function can now be achieved through implementation of the schematic shown in  FIG. 2 . There are seven conditions of operation, which are detailed in the following sections. 
   In Condition 1 (Normal Operation), data for Sector  1  is applied to network input port  220 , amplified by Primary Amplifier  212  and delivered to network output port  225 . Data for sector  2  is applied to network input port  222 , amplified by primary amplifier  213  and delivered to network output port  227 . Data for sector 3 is applied to network input port  224 , amplified by primary amplifier  214  and delivered to network output port  227 . 
   Switch positions and transmission line impedance selections are summarized in Table 1. 
   
     
       
             
             
             
             
             
           
             
             
             
             
             
           
             
             
             
             
             
           
             
             
             
             
             
           
         
             
                 
               TABLE 1 
             
             
                 
                 
             
           
           
             
                 
               Input Circuit 
               Position 
               Input Circuit 
               Value [Ω] 
             
             
                 
                 
             
           
        
         
             
                 
               Switch 230 
               Open 
               Transmission Line 272 
               50 
             
             
                 
               Switch 232 
               Open 
               Transmission Line 262 
               70.7 
             
             
                 
               Switch 234 
               Open 
               Transmission Line 274 
               50 
             
             
                 
               Switch 240 
               Closed 
               Transmission Line 264 
               70.7 
             
             
                 
               Switch 242 
               Closed 
               Transmission Line 276 
               50 
             
             
                 
               Switch 244 
               Closed 
               Transmission Line 266 
               70.7 
             
             
                 
                 
             
           
        
         
             
                 
               Output Circuit 
                 
               Output Circuit 
                 
             
             
                 
                 
             
           
        
         
             
                 
               Switch 235 
               Open 
               Transmission Line 275 
               50 
             
             
                 
               Switch 237 
               Open 
               Transmission Line 265 
               70.7 
             
             
                 
               Switch 239 
               Open 
               Transmission Line 277 
               50 
             
             
                 
               Switch 245 
               Closed 
               Transmission Line 267 
               70.7 
             
             
                 
               Switch 247 
               Closed 
               Transmission Line 279 
               50 
             
             
                 
               Switch 249 
               Closed 
               Transmission Line 269 
               70.7 
             
             
                 
                 
             
           
        
       
     
   
   On the input side, input shunt switches  230 ,  232  and  234  are all open allowing a direct 50Ω path from the network inputs ports  220 ,  222 ,  224  to the Primary Amplifiers  212 ,  213 ,  214 . Input shunt switches  240 ,  242 ,  244  are all closed (shorted to ground), which presents an open at each of the network input ports  220 ,  222 ,  224  and at the Auxiliary Amplifier input port  250 . The open is due to the transformation through the λ/4 length of switchable transmission lines  262 ,  264 ,  266  between the input shunt switches  240 ,  242 ,  244  and the network input ports  220 ,  222 ,  224 . 
   On the output side, output shunt switches  235 ,  237  and  239  are all open, providing a direct 50Ω path from the output of Primary Amplifiers  212 ,  213 ,  214  to network output ports  225 ,  227 ,  229 . Output shunt switches  245 ,  247  and  249  are all closed (shorted to ground), which presents an open at each of the network output ports  225 ,  227 ,  229  and at the Auxiliary Amplifier output port  251 . Again, the open is due to the transformation through the λ/4 length of switchable transmission lines  265 ,  267 ,  269  between the output shunt switches  245 ,  247 ,  249  and the network output ports  225 ,  227 ,  229 . 
   The selection of 70.7Ω for some paths in both the input network  210  and output network  211  will help to improve bandwidth. The switchable transmission lines where 70.7Ω is selected are not part of the signal path for condition 1 but are acting as transformers to convert the short circuit to an open circuit. The higher the impedance of this transmission line transformer, the wider the bandwidth. In other conditions of operation these switchable transmission lines will be part of the main signal path and will require the impedance to be switched between 50 and 70.7Ω. Since this switching is a part of the circuit due to these requirements, it makes sense to take advantage of this function to increase bandwidth. 
   In Condition 2 (Auxiliary Amplifier  215  Replaces Primary Amplifier  212 ), data for Sector  1  is still applied to network input port  220  and delivered to network output port  225  but is redirected through the Auxiliary Amplifier  215 . Data in sectors  2  and  3  continues in the Normal mode as described above. Switch positions and transmission line impedance selections are summarized in table 2. 
   
     
       
             
             
             
             
             
           
             
             
             
             
             
           
             
             
             
             
             
           
             
             
             
             
             
           
         
             
                 
               TABLE 2 
             
             
                 
                 
             
           
           
             
                 
               Input Circuit 
               Position 
               Input Circuit 
               Value [Ω] 
             
             
                 
                 
             
           
        
         
             
                 
               Switch 230 
               Closed 
               Transmission Line 272 
               70.7 
             
             
                 
               Switch 232 
               Open 
               Transmission Line 262 
               50 
             
             
                 
               Switch 234 
               Open 
               Transmission Line 274 
               50 
             
             
                 
               Switch 240 
               Open 
               Transmission Line 264 
               70.7 
             
             
                 
               Switch 242 
               Closed 
               Transmission Line 276 
               50 
             
             
                 
               Switch 244 
               Closed 
               Transmission Line 266 
               70.7 
             
             
                 
                 
             
           
        
         
             
                 
               Output Circuit 
                 
               Output Circuit 
                 
             
             
                 
                 
             
           
        
         
             
                 
               Switch 235 
               Closed 
               Transmission Line 275 
               70.7 
             
             
                 
               Switch 237 
               Open 
               Transmission Line 265 
               50 
             
             
                 
               Switch 239 
               Open 
               Transmission Line 277 
               50 
             
             
                 
               Switch 245 
               Open 
               Transmission Line 267 
               70.7 
             
             
                 
               Switch 247 
               Closed 
               Transmission Line 279 
               50 
             
             
                 
               Switch 249 
               Closed 
               Transmission Line 269 
               70.7 
             
             
                 
                 
             
           
        
       
     
   
   In this case input shunt switch  230  is closed (shorted to ground), presenting an open at network input port  220  and isolating the input of Primary Amplifier  212  from the network. Transmission line  272  is changed to 70.7Ω for the same reason as described above. At the same time input shunt switch  240  is opened and transmission line  262  is switched to 50Ω providing a 50Ω path between network input port  220  and the Auxiliary Amplifier input port  250 . Input shunt switches  232  and  234  are open and input shunt switches  242  and  244  are closed (shorted to ground), which will present opens at network input ports  222  and  224  as well as at the Auxiliary Amplifier input port  250 . 
   On the output side, output shunt switch  235  is closed presenting, an open at network output port  225  and isolating the output of Primary Amplifier  212  from the network. Transmission line  275  is changed to 70.7Ω for the same reason as described above. Output shunt switch  245  is opened and transmission line  265  is switched to 50Ω providing a 50Ω between path the Auxiliary Amplifier output port  251  and network output port  225 . Output shunt switches  237  and  239  are open and output shunt switches  247  and  249  are closed (shorted to ground), which will present opens at network output ports  227  and  229  as well as at the Auxiliary Amplifier output port  251 . 
   In Condition 3 (Auxiliary Amplifier  215  replaces primary amplifier  213 ), data for Sector  2  is still applied to network input port  222  and delivered to network output port  227  but is redirected through the Auxiliary Amplifier  215 . Data for sectors  1  and  3  continues in the Normal mode as described above. Switch positions and transmission line impedance selections are summarized in table 3. 
   
     
       
             
             
             
             
             
           
             
             
             
             
             
           
             
             
             
             
             
           
             
             
             
             
             
           
         
             
                 
               TABLE 3 
             
             
                 
                 
             
             
                 
               Input Circuit 
               Position 
               Input Circuit 
               Value [Ω] 
             
             
                 
                 
             
           
           
             
                 
             
           
        
         
             
                 
               Switch 230 
               Open 
               Transmission Line 272 
               50 
             
             
                 
               Switch 232 
               Closed 
               Transmission Line 262 
               70.7 
             
             
                 
               Switch 234 
               Open 
               Transmission Line 274 
               70.7 
             
             
                 
               Switch 240 
               Closed 
               Transmission Line 264 
               50 
             
             
                 
               Switch 242 
               Open 
               Transmission Line 276 
               50 
             
             
                 
               Switch 244 
               Closed 
               Transmission Line 266 
               70.7 
             
             
                 
                 
             
           
        
         
             
                 
               Output Circuit 
                 
               Output Circuit 
                 
             
             
                 
                 
             
           
        
         
             
                 
               Switch 235 
               Open 
               Transmission Line 275 
               50 
             
             
                 
               Switch 237 
               Closed 
               Transmission Line 265 
               70.7 
             
             
                 
               Switch 239 
               Open 
               Transmission Line 277 
               70.7 
             
             
                 
               Switch 245 
               Closed 
               Transmission Line 267 
               50 
             
             
                 
               Switch 247 
               Open 
               Transmission Line 279 
               50 
             
             
                 
               Switch 249 
               Closed 
               Transmission Line 269 
               70.7 
             
             
                 
                 
             
           
        
       
     
   
   In this case input shunt switch  232  is closed (shorted to ground), presenting an open at network input port  222  and isolating the input of Primary Amplifier  213  from the network. Transmission line  274  is changed to 70.7Ω for the same reason as described above. At the same time input shunt switch  242  is opened and transmission line  264  is switched to 50Ω providing a 50Ω path between network input port  222  and the Auxiliary Amplifier input port  250 . Input shunt switches  230  and  234  are open and input shunt switches  240  and  244  are closed (shorted to ground), which will present opens at network input ports  220  and  224  as well as at the Auxiliary Amplifier input port  250 . 
   On the output side, output shunt switch  237  is closed presenting an open at network output port  227  and isolating the output of Primary Amplifier  213  from the network. Transmission line  277  is changed to 70.7Ω for the same reason as described above. Output shunt switch  247  is opened and transmission line  267  is switched to 50Ω providing a 50Ω between path the Auxiliary Amplifier output port  251  and network output port  227 . Output shunt switches  235  and  239  are open and output shunt switches  245  and  249  are closed (shorted to ground), which will present opens at network output ports  225  and  229  as well as at the Auxiliary Amplifier output port  251 . 
   In Condition 4 (auxiliary amplifier  215  replaces primary amplifier  214 ), data for Sector  3  is still applied to network input port  224  and delivered to network output port  229  but is redirected through the Auxiliary Amplifier  215 . Data in sectors  1  and  2  continues in the Normal mode as described above. Switch positions and transmission line impedance selections are summarized in table 4. 
   
     
       
             
             
             
             
             
           
             
             
             
             
             
           
             
             
             
             
             
           
             
             
             
             
             
           
         
             
                 
               TABLE 4 
             
             
                 
                 
             
           
           
             
                 
               Input Circuit 
               Position 
               Input Circuit 
               Value [Ω] 
             
             
                 
                 
             
           
        
         
             
                 
               Switch 230 
               Open 
               Transmission Line 272 
               50 
             
             
                 
               Switch 232 
               Open 
               Transmission Line 262 
               70.7 
             
             
                 
               Switch 234 
               Closed 
               Transmission Line 274 
               50 
             
             
                 
               Switch 240 
               Closed 
               Transmission Line 264 
               70.7 
             
             
                 
               Switch 242 
               Closed 
               Transmission Line 276 
               70.7 
             
             
                 
               Switch 244 
               Open 
               Transmission Line 266 
               50 
             
             
                 
                 
             
           
        
         
             
                 
               Output Circuit 
                 
               Output Circuit 
                 
             
             
                 
                 
             
           
        
         
             
                 
               Switch 235 
               Open 
               Transmission Line 275 
               50 
             
             
                 
               Switch 237 
               Open 
               Transmission Line 265 
               70.7 
             
             
                 
               Switch 239 
               Closed 
               Transmission Line 277 
               50 
             
             
                 
               Switch 245 
               Closed 
               Transmission Line 267 
               70.7 
             
             
                 
               Switch 247 
               Closed 
               Transmission Line 279 
               70.7 
             
             
                 
               Switch 249 
               Open 
               Transmission Line 269 
               50 
             
             
                 
                 
             
           
        
       
     
   
   In this case input shunt switch  234  is closed (shorted to ground) presenting an open at network input port  224  and isolating the input of Primary Amplifier  214  from the network. Transmission line  276  is changed to 70.7Ω for the same reason as described above. At the same time input shunt switch  244  is opened and transmission line  266  is switched to 50Ω providing a 50Ω path between network input port  224  and the Auxiliary Amplifier input port  250 . Input shunt switches  230  and  232  are open and input shunt switches  240  and  242  are closed (shorted to ground), which will present opens at network input ports  220  and  222  as well as at the Auxiliary Amplifier input port  250 . 
   On the output side, output shunt switch  239  is closed presenting an open at network output port  229  and isolating the output of Primary Amplifier  214  from the network. Transmission line  279  is changed to 70.7Ω for the same reason as described above. Output shunt switch  249  is opened and transmission line  269  is switched to 50Ω providing a 50Ω between path the Auxiliary Amplifier output port  251  and network output port  229 . Output shunt switches  235  and  237  are open and output shunt switches  245  and  247  are closed (shorted to ground), which will present opens at network output ports  225  and  227  as well as at the Auxiliary Amplifier output port  251 . 
   In Condition 5 (Auxiliary Amplifier in parallel with primary amplifier  212 ), data for Sector  1  is still applied to network input port  220  and delivered to network output port  225 . The signal is split and amplified by both Primary Amplifier  212  and the Auxiliary Amplifier  215 . Data in sectors  2  and  3  continues in the Normal mode as described above. Switch positions and transmission line impedance selections are summarized in table 5. 
   
     
       
             
             
             
             
             
           
             
             
             
             
             
           
             
             
             
             
             
           
             
             
             
             
             
           
         
             
                 
               TABLE 5 
             
             
                 
                 
             
           
           
             
                 
               Input Circuit 
               Position 
               Input Circuit 
               Value [Ω] 
             
             
                 
                 
             
           
        
         
             
                 
               Switch 230 
               Open 
               Transmission Line 272 
               70.7 
             
             
                 
               Switch 232 
               Open 
               Transmission Line 262 
               70.7 
             
             
                 
               Switch 234 
               Open 
               Transmission Line 274 
               50 
             
             
                 
               Switch 240 
               Open 
               Transmission Line 264 
               70.7 
             
             
                 
               Switch 242 
               Closed 
               Transmission Line 276 
               50 
             
             
                 
               Switch 244 
               Closed 
               Transmission Line 266 
               70.7 
             
             
                 
                 
             
           
        
         
             
                 
               Output Circuit 
                 
               Output Circuit 
                 
             
             
                 
                 
             
           
        
         
             
                 
               Switch 235 
               Open 
               Transmission Line 275 
               70.7 
             
             
                 
               Switch 237 
               Open 
               Transmission Line 265 
               70.7 
             
             
                 
               Switch 239 
               Open 
               Transmission Line 277 
               50 
             
             
                 
               Switch 245 
               Open 
               Transmission Line 267 
               70.7 
             
             
                 
               Switch 247 
               Closed 
               Transmission Line 279 
               50 
             
             
                 
               Switch 249 
               Closed 
               Transmission Line 269 
               70.7 
             
             
                 
                 
             
           
        
       
     
   
   In this case input shunt switch  240  is open and transmission lines  272  and  262  are both set to 70.7Ω. With these settings, a signal applied to network input port  220  will be equally split between the paths leading to Primary Amplifier  212  and the Auxiliary Amplifier  215  (the circuit is now configured as the common Wilkinson Power Divider without an internal termination resistor). In the output network  211 , the circuit is configured to function as a combiner, combining the output of primary amplifier  212  and auxiliary amplifier  215 . To achieve this, output shunt switch  245  is open and transmission lines  275  and  265  are both set to 70.7Ω. 
   In Condition 6 (Auxiliary Amplifier In Parallel With Primary Amplifier  213 ), data for Sector  2  is still applied to network input port  222  and delivered to network output port  227 . The signal is split and amplified by both Primary Amplifier  213  and the Auxiliary Amplifier  215 . Data in sectors  1  and  3  continues in the Normal mode as described above. Switch positions and transmission line impedance selections are summarized in table 6. 
   
     
       
             
             
             
             
             
           
             
             
             
             
             
           
             
             
             
             
             
           
             
             
             
             
             
           
         
             
                 
               TABLE 6 
             
             
                 
                 
             
           
           
             
                 
               Input Circuit 
               Position 
               Input Circuit 
               Value [Ω] 
             
             
                 
                 
             
           
        
         
             
                 
               Switch 230 
               Open 
               Transmission Line 272 
               50 
             
             
                 
               Switch 232 
               Open 
               Transmission Line 262 
               70.7 
             
             
                 
               Switch 234 
               Open 
               Transmission Line 274 
               70.7 
             
             
                 
               Switch 240 
               Closed 
               Transmission Line 264 
               70.7 
             
             
                 
               Switch 242 
               Open 
               Transmission Line 276 
               50 
             
             
                 
               Switch 244 
               Closed 
               Transmission Line 266 
               70.7 
             
             
                 
                 
             
           
        
         
             
                 
               Output Circuit 
                 
               Output Circuit 
                 
             
             
                 
                 
             
           
        
         
             
                 
               Switch 235 
               Open 
               Transmission Line 275 
               50 
             
             
                 
               Switch 237 
               Open 
               Transmission Line 265 
               70.7 
             
             
                 
               Switch 239 
               Open 
               Transmission Line 277 
               70.7 
             
             
                 
               Switch 245 
               Closed 
               Transmission Line 267 
               70.7 
             
             
                 
               Switch 247 
               Open 
               Transmission Line 279 
               50 
             
             
                 
               Switch 249 
               Closed 
               Transmission Line 269 
               70.7 
             
             
                 
                 
             
           
        
       
     
   
   In this case input shunt switch  242  is open and transmission lines  274  and  264  are both set to 70.7Ω. With these settings, a signal applied to network input port  222  will be equally split between the paths leading to Primary Amplifier  213  and the Auxiliary Amplifier  215  (the circuit is now configured as the common Wilkinson Power Divider without an internal termination resistor). In the output network, the circuit is configured to function as a combiner. To achieve this, output shunt switch  247  is open and transmission lines  277  and  267  are both set to 70.7Ω. 
   In Condition 7 (auxiliary amplifier  215  in parallel with primary amplifier  214 ), data for Sector  3  is still applied to network input port  224  and delivered to network output port  229 . The signal is split and amplified by both Primary Amplifier  214  and the Auxiliary Amplifier  215 . Data in sectors  1  and  2  continues in the Normal mode as described above. Switch positions and transmission line impedance selections are summarized in table 7. 
   
     
       
             
             
             
             
             
           
             
             
             
             
             
           
             
             
             
             
             
           
             
             
             
             
             
           
         
             
                 
               TABLE 7 
             
             
                 
                 
             
           
           
             
                 
               Input Circuit 
               Position 
               Input Circuit 
               Value [Ω] 
             
             
                 
                 
             
           
        
         
             
                 
               Switch 230 
               Open 
               Transmission Line 272 
               50 
             
             
                 
               Switch 232 
               Open 
               Transmission Line 262 
               70.7 
             
             
                 
               Switch 234 
               Open 
               Transmission Line 274 
               50 
             
             
                 
               Switch 240 
               Closed 
               Transmission Line 264 
               70.7 
             
             
                 
               Switch 242 
               Closed 
               Transmission Line 276 
               70.7 
             
             
                 
               Switch 244 
               Open 
               Transmission Line 266 
               70.7 
             
             
                 
                 
             
           
        
         
             
                 
               Output Circuit 
                 
               Output Circuit 
                 
             
             
                 
                 
             
           
        
         
             
                 
               Switch 235 
               Open 
               Transmission Line 275 
               50 
             
             
                 
               Switch 237 
               Open 
               Transmission Line 265 
               70.7 
             
             
                 
               Switch 239 
               Open 
               Transmission Line 277 
               50 
             
             
                 
               Switch 245 
               Closed 
               Transmission Line 267 
               70.7 
             
             
                 
               Switch 247 
               Closed 
               Transmission Line 279 
               70.7 
             
             
                 
               Switch 249 
               Open 
               Transmission Line 269 
               70.7 
             
             
                 
                 
             
           
        
       
     
   
   In this case input shunt switch  244  is open and transmission lines  276  and  266  are both set to 70.7Ω. With these settings, a signal applied to network input port  224  will be equally split between the paths leading to Primary Amplifier  214  and the Auxiliary Amplifier  215  (the circuit is now configured as the common Wilkinson Power Divider without an internal termination resistor). In the output network, the circuit is configured to function as a combiner. To achieve this, output shunt switch  249  is open and transmission lines  279  and  269  are both set to 70.7Ω. 
   This network is made up of transmission line that can change impedance between 50 and 70.7Ω and having specific electrical lengths and switches providing ground at specific locations along these transmission lines. The switches are always shunt (to ground) and never in series with the transmission lines. This will prove beneficial for both electrical performance (i.e. insertion loss) and for ease in implementation. 
   Impedance and electrical lengths as well as the quality of the short circuit connection provided by the switch must be controlled to provide good system impedance match. 
   Minimum insertion loss is paramount mainly in the output network. This will help system efficiency as well thermal issues due to power dissipation. 
   It is undesirable for data intended for any one sector to be present at the output port for any other sector. It is primarily the quality of grounding at the shunt switches that influences this parameter. 
   It can be seen in  FIG. 2  that the path lengths between any network input port and any amplifier input are of equal electrical length. Also, the path lengths between any amplifier output and any network output port are of equal electrical length. This is a requirement in this embodiment because in Conditions 5, 6 &amp; 7 the signal is being split and then recombined. These functions require that the signal paths have equal electrical length through all paths. If any additional path length is added during implementation of this circuit, it must be applied in such away that maintains equal length among the different paths. 
   While there has been illustrated and described what are at present considered to be preferred and alternate embodiments of the present invention, it should be understood and appreciated that modifications may be made by those skilled in the art, and that the appended claims encompass all such modifications that fall within the full spirit and scope of the present invention.