ANGLE-OF-ARRIVAL MEASUREMENTS 
-+-0.27° above true bearing in place of -+-0.46°, were 
the receiver and transmitter interchanged at the end 
points of the path. On the other hand, for both cases 
1 and 2 treated above, the meteorological stratification 
was such that the angular deviations from true bear- 
ing at both receiver and transmitter were the same. 
The relations of the angular deviations from true 
bearing at the end points of the path are summarized 
in Figure 7. 
A fourth conclusion can be deduced by considering 
the curve in Figure 7 based on the computations tab- 
ulated in Table 3. It will be recalled that a fluctuation 
of 0.1° in angle of arrival at the receiver was con- 
cluded as possible as a result of relatively small fluc- 
tuations in the meteorological elements in the layer 
immediately above the transmitter. But it should now 
be noted that fluctuation of angle of departure at the 
New York transmitter is approximately 0.25° when 
the Beer’s Hill angle of arrival varies approximately 
HUNDREDTHS OF DEGREE 
-20 -10 O 
10 20 30 40 -20 -10 O 
6 JULY 3 JULY 1 JULY 
7 JUEY 
6 JULY 
COMPARISON OF EXPERIMENTAL 
ANGLE OF ELEVATION MEASURE- 
MENTS (BTL BEER'S HILL — 
NEW YORK GIRGUIT, 1944) 
WITH METEOROLOGICALLY 
DEDUCED ANGLES 
HUNDREDTHS OF DEGREE 
323 
0.1° for the particular meteorological situation of 
0800 on July 7, 1944. 
It therefore follows, in summary, that the deviation 
from true bearing measured at the position of the re- 
ceiver depends not only on the range between trans- 
mitter and receiver and on the meteorological condi- 
tions but also and equally well on the relative differ- 
ence in heights of transmitter and receiver and the 
position in height of the receiver with respect to the 
transmitter. 
Comparison of Computed to 
Measured Angle of Arrival 
The experimental measurements of angle of ar- 
rival secured by Bell Telephone Laboratories and the 
meteorological data obtained on the 400-ft tower in 
Oakhurs|, have been analyzed to determine whether 
any significant correlations exist between the meas- 
HUNDREDTHS OF DEGREE 
0 20 30 40 -20 -0 O 10 20 30 40 
NO MEASUREMENT OF 
ANGLE OF ARRIVAL 
POSSIBLE 
3 ‘ 
= 
Nw 
e 
7) 
2 
oO 
=) 
< 
KR 
Ke 
o” 
=) 
oOo 
2 
on 
2 
2 
< 
C2) 
e 
wo 
=) 
3 RAPID PHASE CHANGES 
© BYL RADIO MEASUREMENT 
(ACCURACY +.04°) 
ANGLE AT BEER'S HILL 
COMPUTED FROM METEOR - 
OLOGICAL SOUNDING ON 
400-FOOT TOWER, 
OAKHURST, NJ 
VERTICAL SOLID LINE AT -.II- 
REPRESENTS TRUE GEOMETRIC 
BEARING FROM BEER'S HILL 
RECEIVER TO NEW YORK 
TRANSMITTER 
Ficure 8. Measured versus computed angles of arrival. 
