ULTRA-SHORT-WAVE TRANSMISSION 505 



was had at East Moriches and West Sayville, on three days. The 

 survey data were not sufficient to establish any proposition beyond 

 the statement that the signal strength fell rapidly with distance, with 

 the intensity of fading coming up as the signal fell. The simultaneous 

 two-distance recording showed random fading between the two 

 records with less fading amplitude at the shorter distance. The 

 fading rate was about the same. Unfortunately the recording took 

 place under scintillation conditions, thus giving very poor records for 

 comparison purposes. 



By mounting two linear doublets on the 60-foot lattice mast simul- 

 taneous recording at two heights was carried out. For the two dou- 

 blets (horizontal, at 14 and 52 feet respectively), a signal level difference 

 of 12 db was observed, in favor of the higher antenna. The fading on 

 the two records was identical. It may be added that, on calibrating 

 the car receiver at East Moriches before moving to West Sayville, 

 identical fading records were obtained with the two antenna systems 

 150 feet (45.7 meters) apart and substantially broadside to the 

 radiation. 



Frequency Sweep Patterns of Fading 



The frequency sweep patterns were of many types, from slow to fast 

 fading and from shallow to deep fading. Apparent path differences 

 from 600 meters down to a few meters occurred. The patterns were 

 usually complicated, indicating that more than two components were 

 present. There is no reason to believe, however, that they were not 

 all due to wave interference.^* 



On three days the predominant pattern was simple enough to be 

 referable to two waves with a path difference consistently greater than 

 75 meters. These will be referred to later. In Figure 13 are given 

 three sample runs illustrating a two-component pattern, a three- 

 component pattern with two of the components forming a small path 

 difference pair, and a multiple component pattern. The receiver 

 characteristic is dotted in on one curve of each set. 



Logs During Weather Bureau Airplane Flights 



On forty-five mornings recording was carried out during the period 

 of flight of the Mitchel Field Weather Bureau plane. This plane takes 

 off about dawn every morning, when flying is possible, and by means 

 of a meteorograph obtains records of air pressure, temperature and 

 humidity, up to an altitude of about five kilometers. A record of the 

 fading, on 4.7 meters and vertical polarization, was obtained for each 

 of these mornings. In addition, on twenty-six mornings frequency 



