ULTRA-SHORT-WAVE TRANSMISSION 



513 



("yl " component as triangles, "5" component as circles) are plotted 

 on Fig. 17 together with the maximum and median * observed values. 

 These latter are joined by lines. For the 10 mornings on which no 

 boundaries were evident the calculated "5" component appears to 

 be some 8 db higher than the observed values. With this correction 

 the agreement between observed and total calculated fields is fairly 

 good. A partial explanation of this 8 db discrepancy may lie in the 

 fact that the ocean water trajectory assumed in the calculation differs 

 from the actual one by the land terminals and the three tongues of land 

 intervening. 



1 - BOUNDARY EVIDENT 



AC* tO-S 

 2 -NO BOUNDARY 



3 - SMALL BOUNDARY 



AetlO"^ 



4 - INDEFINITE BOUNDARY 



6- POSSIBLE BOUNDARY 

 BELOW 400 METERS 



-M*-3- 



a 50 



-c^i 



o °o n o4> °0 $ 



tr^ 



a — O-Q- 



_J I I I I I L 



- rf) -^ to fO 



, CVJftl „(\1 



I I I I I I I I I I I 



4- CALC. "A" COMPONENT r^-OBSERVED MAXIMUM 



0-CALC."B" COMPONENT L— OBSERVED MEDIAN 



•LAKEHURST DATA "A" 



Fig. 17 — Comparison of "^" and "S" radiation components, calculated from 

 the U. S. Weather Bureau free air data, with measured maximum and median signal 

 strengths. Vertically polarized transmission. 



On the twenty-six morning frequency sweep runs there were only 

 three on which the predominant sweep pattern was simple enough to be 

 interpreted as due to two components with path difference greater 

 than 75 meters. For those days a series of measurements of the film 

 patterns was made by determining the frequency spacing between 

 a maximum and a minimum and calculating the resulting path dif- 

 ference and boundary height. The dielectric constant-height function 

 was also calculated from the Weather Bureau data. These curves are 



* The signal is half of the time greater and half of the time less than its median 

 value. For random phase with "S" component equal to "A" component the 

 resultant median value signal is V2 X ^ or 3 db up; it falls from this value to "A " 

 as "B" decreases to zero. 



