ULTRA-SHORT-WAVE TRANSMISSION PHENOMENA 



379 



for 4.6 meters, and the plane noise level was higher. It appears, from 

 some rough tests made, that a metal plane is likely to have a peak 

 noise range determined by the natural period of the smaller metal 

 parts, which can vibrate and make variable contact during operation. 

 The " out " curves show the same roughness that was found at the 

 other altitudes. If this effect had been discovered in time, it would 



1 25 



> 20 



10 20 30 40 50 60 70 80 90 100 110 120 130 



MILES FROM TRANSMITTER 



Fig. 9 — Flight toward transmitter. Wave-length — 4.6 meters; Altitude — 1000 feet; 

 October 3, 1933; 11:30 a.m. to 12:35 p.m. 



certainly have been advisable to move the receiving antenna, so as to 

 shift the polar characteristic minimum to some other angle. 



The curves of Fig. 12 were taken at 4.6 meters on passing from the 

 1000- to the 8000-foot level and vice versa. The first one, taken at 

 Montauk Point on September 27, shows very little variation in signal 

 strength in spiraling up from 1000 to 8000 feet. This was the day 

 when our maximum atmospheric refraction was encountered. If we 

 assume a refraction sufficient to bend the radiation into a circle around 



