Beam Forming And Steering 



Two approaches were used to produce the desired amplitude and phase at 

 the element terminals on the SAMB antenna: one employing a matrix, and the 

 other, true-time-delay lines. A Taylor distribution in amplitude that would yield 

 side lobes on the order of -27 dB was chosen. 



A 32-port matrix 4 was designed and constructed under contract by 

 Radiation Systems, Inc., Alexandria, Virginia. This matrix is capable of producing 

 a single beam at a given angle for each input terminal excited, or will yield simul- 

 taneous multiple beams if all of the input terminals are excited simultaneously. 

 The device is so constructed that the correct amplitude and phase are applied to 

 the antenna terminals to provide for 28 different beam positions. A diode switch- 

 ing matrix developed by NELC allows sequential or jump scanning as desired. 

 Figure 3 shows this system in block diagram. Details of the matrix switches are 

 given in reference 5. 



The true-time-delay system for amplitude and phase control was designed 

 and constructed under contract to Sylvania Electronic Systems, Waltham, 

 Massachusetts. This method employed a 1:32 power divider to yield the Taylor 

 amplitude distribution. Each of the 32 output ports of the power divider was con- 

 nected to a five-bit time-delay board consisting of 32 possible true-time-delay 

 path lengths for each element. Programmed microwave diode switches were used 

 to select the proper line length to give a selected beam direction. Figure 4 shows 

 this system in block diagram. 



