Radar System Engineering

592 EXAMPLES OF RADAR SYSTEM DESIGN [SEC, 153
rwmber of such surveys of ground, ship, and airborne 10-cm and 3-cm
radars during the years 1943 and 1944. The radar performance figure
of the average set tested was 14 or 15 db below the rated value for the
radar. Since a performance-figure deficit of 12 db results in cutting the
maximum range of the set on aircraft by a factor of 2 (Fig. 15.1), poor
radar performance was responsible for a loss of more than half the
tactical usefulness of the systems tested. Figure 15.3 shows the findings
of a more recent (July 1945) survey covering 10-cm ship radars; it indicates
that there had been no change for the better.
Such serious deficiencies in actual field radar performance emphasize
the fact that the use of test equipment to measure performance and to
trace down the causes of impaired performance had not been incorporated
into routine maintenance practice for most radar sets at the end of the
L
01
o 10 20 30 40
Oedels below rated performance
?
%6
*
z
~4
2
22
0k
o 10 20 30 40
Oeabels below rated performance
FIG. 15.2.—Radar performance surveys, FIG. 15.3.—Radar performance survey,
1943–1 944. July 1945.
war. Such important losses in performance are glaringly inconsistent
with the great effort expended in radar design to attain high performance.
In the design of new equipment, it is essential to make careful provision
for adequate testing and trouble-shooting; in the use of existing equipment
it is equally important to be sure that routine maintenance procedure is
sufficient to keep the radar within a few decibels of rated performance.
The design and use of test equipment is treated in detail in Vol. 23 of
this series.
DESIGN OF A HIGH-PERFORMANCE RADAR FOR
AIR SURVEILLANCEAND CONTROL
15.3. Initial Planning and Objectives. Formtdation of Requirements.
At a relatively early stage in the development of microwave techniques
consideration was given to the possibility of applying them to the problem
of long-range air surveillance. Greatly improved azimuth resolution,
minimization of ground “ clutter, ” and improved low-angle coverage were
the principal advantages that microwaves appeared to offer, The best