Radar System Engineering

114 PROPERTIES OF RADAR TARGETS [SEC. 317
tion, while with systems of less resolution but greater range it is often
the spatial relationship of a group of targets which results in their
identification.
In mountainous regions the presentation of a given area varies considerably
with the altitude and position of the observing aircraft, and
skill is required in using radar pilotage over this sort of terrain. How-
N
Frc. 339.-Pacific Coast near Balboa, c.Z. Average water-vapor conrcntration over
fight path 6.9 .g/m~, Wavelength = 1,25 cm, 0.8° beam, altitude 20,000ft, ~adiu~23
nauhctilmi. 9“01’.N.79”35’TV.
ever, the Fifteenth Air Force of the U.S. Army has used the method
extensively in navigating across the Alps. One difficulty inherent in
the use of radar pilotage over mountainous terrain is illustrated in
Fig. 3-K). N-est of theaircraft amountai nchainrisin gto6000ft throws
long shadowsintothe 310gami Yalley beyond. ‘1’heto\vnof Yarnagata
is seen as a bright signal beyond a spur of Mt. Taki extending northwest