MEASUREMENT OF IMPEDANCE MISMATCHES 



449 



represented as in Fig. 3, where vector 0-1 represents the voltage reflected 

 from couphng BE and vector 1-2 represents the voltage reflected from the 

 termination Z. To make measurements, termination Z should be movable 



4-0 



30 40 



W IN DB 



Fig. 2 — Standing wave ratio (SWR) versus W. 



and the magnitude of its reflection coefiicient be the same at a given position 

 of rest for either direction of approach, and be the same for positions of rest 

 over an interval of a half a w^avelength in waveguide. 



The reflected voltage is measured twice, once for minimum output as the 

 position of the termination Z is adjusted and again for maximum output. 

 Then 



Fn^in = Fb - F. and V^^ = Vb+V, (8) 



