Figure 2-35.—Seven-foot shf SATCOM antenna.
Figure 2-36.—Four-foot shf SATCOM antenna.
MATCHING NETWORKS
An antenna matching network consists of one or
more parts (such as coils, capacitors, and lengths of
transmission line) connected in series or parallel with
the transmission line to reduce the standing wave ratio
on the line. Matching networks are usually adjusted
when they are installed and require no further
adjustment for proper operation. Figure 2-37 shows
a matching network outside of the antenna feedbox,
with a sample matching network schematic.
Matching networks can also be built with variable
components so they can be used for impedance
matching over a range of frequencies. These networks
are called antenna tuners.
Antenna tuners are usually adjusted automatically
or manually each time the operating frequency is
changed. Standard tuners are made with integral
enclosures. Installation consists simply of mounting
2-20
