288 



BELL SYSTEM TECHNICAL JOURNAL 



suitably adjusting the positions of the pistons with respect to the 

 source and the power absorber, and by a proper choice of the distance 

 between the source and the power absorber, the impedance of the 

 latter can be matched to that of the source, so as to ensure the maximum 

 delivery of power. 



500 



2 300 



£ 250 



u 



<■ 200 



150 



50 



50 100 150 200 250 300 350 400 450 



PLATE VOLTAGE 



Fig. 5 — "No Load" oscillation domain of diodes no. 24 and no. 37. 



The power absorbing and measuring element shown on Fig. 6 repre- 

 sents a new and useful way of measuring power at the very high fre- 

 quencies involved in this investigation. It makes use of the high 

 negative temperature coefificient of resistance of boron. In the middle 



