SITING AND COVERAGE OF GROUND RADARS 
DEGREES" |5 ! 
32000 
28000 
24000 
20000 
16000 
eA 
wi 
12000 
ALTITUDE IN FEET 
a 
a 
— 
8000 
4000 
MODIFIED EARTH'S SURFACE 
| 
OL, = 60 SIN 90°N 
109 
= 
10 9F 8 
L/ 
2 
Na 
i 
Saas 
2 Aa oo 
Vee pen 
RS 
He 
: FIRST LOBE 
Ni 
ie 
eS 
N, 
E 
i 
ie 
\ 
If = 200 Mc 
dwax = 60 MILES 
40 
DISTANCE dq IN MILES 
Fiaure 56. Low site lobes. (Example 14 ) 
two waves. Low sites are generally free from the 
above effects and equation (74) may be used with 
acceptable accuracy. 
Example 14. Low Site Lobes. A radar operating on 
200 me is 25 ft high and has a maximum range of 
60 miles. The lobes occur at 2.82°, 8.46°, and 14.1° 
and the nulls at 0°, 5.64°, 11.28°. The method of 
plotting a lobe is shown in Figure 56. n may be 
divided into as many parts as desired, and the 
corresponding range for each obtained from equa- 
tion (74). Thus at » = 0.7 the angle is 
0.7 X 4.92 
4 X 25 
d = 60 sin (90° X 0.7) = 53.46 miles. 
= 0.0344 radian , 
