Radar System Engineering

190 THE GATHERING AND PRESENTATION OF RADAR DATA [SEC.612
to move the scanning range to the elevation interval from 7# to 15°.
Elevation can be read to an accuracy of + 0.15° and readings can be
obtained to a maximum range of about 70 miles.
The 120-ft svstem consists of nine groups of fom dipoles each, stacked
vertically. Its scan covers the range of elevation angles from lY to 15°.
Elevation angle readings can be obtained to an accuracy of + 0.3° out to
about 55 miles range.
The horizontal antenna pattern of both sets is a fixed widt beam
covering approximately 60° on either side of a predetermined ‘‘ !inc of
shoot ‘‘
The indicator is an E-scope in which a horizontal intensity-modl~i~ te(i
range s~veep moves vertically up the tube in synchronism with tlw ~n~nw-
FIG. 622,-British
A.Y1.E.S. Type 13height findeI
ment of the radar beam. Signals appear as vertical lines 3,+a cwtain
range along the trace centered shout the elevation angle ti the targe~.
Calculation of height from range and elevation angle L pcriormwi
automatically by the selector s\vitch and relay equipment lw’J in t’ Ii
stations (Sec. 6.9). The range and elevation of the targe~ m-e set into
the computer by the operator, who adjusts range and angl~ lliarkrts tc
cross at the center of the target signal on the scope. ‘:-he r,v,>.puter
indicates target height in numerals on a lamp display.
Development of the microwave art permitted the design of ckv,’at,ionscanning
height finders which, unlike the J7EB, could be made mdule.
The first such set to be used operationally was the British Type L3. The
reason for the late appearance of this very successful height finder is the
technical difficulty of illuminating an antenna reflector of large aperture
ratio. This is accomplished in the Type 13 by illuminating a double
“cheese” (Fig. 6.22) by means of a horn feed (Chap. 9). Although side