frequency (435 MHz) than the earlie

frequency (435 MHz) than the earlier brassboard systems. The goal was to obtain a more
accurate location of personnel at much longer ranges. Lincoln Laboratory developed an
initial Camp Sentinel II service test system using a solid-state transmitter and a
mechanically scanned antenna. This early system had a moderate detection range up to
200 meters [6].
In order to provide longer detection range and counter higher losses at UHF, the
system was upgraded to Camp Sentinel III with a high power-aperture design. A 3.5-
meter-diameter, 1-meter-high cylindrical antenna was developed through the Army
Harry Diamond Laboratory. This antenna was mounted on a 33-meter-high tower along
with a 2-kilowatt tube transmitter. The high tower was chosen primarily to extend the
propagation range out to 2 kilometers. Stepped angle surveillance with 32 beam positions
was provided by the cylindrical antenna, shown in Figure 14-2. This stepped scan