ELECTROMAGNETIC WAVE PROPAGATION STUDIES 



The propagation and reception of very low frequency (vlf) 

 electromagnetic waves underwater have been investigated utilizing 

 the tower's vertical railway system to achieve preselected depths. 



Measurements of subsurface signal attenuation made dur- 

 ing this period revealed that the tower structure has a negligible 

 effect on wave reception to a depth of 35 feet. The tower also 

 provided the requirements of open-sea, natural-wave conditions 

 and unsheltered exposure. An additional advantage was the tower's 

 stability, which permitted the collection of more data at less cost 

 than could have been obtained by use of a relatively unstable 

 submersible. 



VLF Transmission 



65 



