Page 197 - Satellite Communications, Fourth Edition
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Antennas 177
Figure 6.28 A multifeed contained-beam reflector antenna. (Courtesy of Brain and
Rudge, 1984.)
practical scanning arrays, steps are taken to avoid this. A detailed dis-
cussion of arrays will be found in Kummer (1992).
Arrays may be used directly as antennas, and details of a nine-horn
array used to provide an earth coverage beam are given in Hwang
(1992). Arrays are also used as feeders for reflector antennas, and such
a horn array is shown in Fig. 6.28.
6.18 Planar Antennas
A microstrip antenna is an antenna etched in one side of a printed cir-
cuit board, a basic patch antenna being as sketched in Fig. 6.29a. A vari-
ety of construction techniques are in use, both for the antenna pattern
