614 lU.Li. srsrr.M iechxic.il jol'i^x.ii. 



To obtain the separate \alues of '/„(, and 7'),,,, ii is neressar\- \n 

 make at least one two-point measurement, as seen Irimi the rorniuia 

 lor //, which ccjntains four distinct transducer parameters. For 

 example, to lind 7",,;, perhaps the simplest method is to terminate 

 with the image impedance at terminals h, whence 



'l\,t, = \ogAL /(,). where Z,,= IT/,. I()2l 



The cimstaiit Ti.,, is the difference between the sum {'r„i,+ Th„}. 

 iilitained from (.")7i, and 7',,;,; it may also be determined 1)\- a two- 

 [joint measurement similar to the abo\e for transmission in the oppo- 

 site direction. 



h'or some i^urposes it is con\enienl to have formulae in\ol\ing the 

 potential differences I',, and Vb across the two ])airs of terminals, 

 rather than the terminal impedances Za and Zi, and the series applied 

 electromoti\e force E,,. Such formulae in combination with the 

 abo\e can be used to advantage in determining the curretits and 

 potential differences at points within a composite transducer. TIicn 

 are deri\ed re.idiK' l)\' making the siibstiiuiions in the al)o\e, 



and (1)3) 



Zb = Vb lb- 



For cnrrcnl iransmission from terminals « to terminals/) 





and I (it I 



IF,, /p^'"' + (-•'■'■ 

 ^ ,1 = I I 



Also, 



and 



■/,= ! 



. IF,,/'e^"'" + c"'"''\ , ... (e'r'-'-f-T-\ 



Interchanging the subscripts and changing the signs of the cm-rents 

 in (()4) will also lead to (().')). 



2. Passive Linear Transducer. Since the ri'iiprnc.il ilu-dicin Imld^ 

 here one relation exists between the foin- paranuteis Icuing ilircc 



