408 BELL SYSTEM TECHNICAL JOURNAL 



Resonance Period of a Straight Rod 



It was at first thought that it would be relatively simple to set up 

 a vacuum tube generator together with a rectilinear rod and run 

 resonance curves on the latter. This did not prove to be the case 

 however. Working indoors was impossible and all the apparatus 

 had to be moved out of doors. When the two antennas (the generator 



Fig. 2 



antenna and resonant rod) were mounted vertically, the operator 

 became a mobile reflector himself seriously disturbing the transmission. 

 Moreover the ground was unsymmetrically disposed with respect to 

 the two antenna ends and this was felt to be a disadvantage. With 

 the antennas horizontal these objections vanished but the reflection 

 from the ground had to be taken into account. This latter was the 

 arrangement finally adopted and is shown in Fig. 3, the apparatus in 

 question being mounted on the two tripods. 



The attempt was made to get a generator whose radiation field 

 was constant over a wide wave length range so that the rod resonance 

 wave length could be obtained by observation while turning the 

 generator tuning condenser. As a matter of fact, the generator 

 output was apparently satisfactorily constant while actually not so. 



