Figure 117.
Waveguide Terminated With a
Dummy Load.
20. Reviewing methods of coupling energy from a waveguide.
a. The main purpose of waveguide is to couple RF energy to an antenna,
a dummy load, or test equipment.
b. Waveguide is usually coupled to a reflector through an impedance-
matching device called a horn.
c. Waveguide is usually coupled to test equipment through a directional
coupler which takes a sample of the energy in the waveguide.
d. A dummy load absorbs RF energy and is connected to waveguide to
prevent radiation.
e. The energy fed to a dummy load is dissipated in the form of heat.
f. So far we have spoken only about rectangular waveguide, but in some
applications round waveguide is used. One such case is when we want one end
of the waveguide to rotate while the other end remains stationary. The best
example of this is when waveguide is used to guide energy from a transmitter
to a rotating antenna. The waveguide section connected to the transmitter
must remain stationary, but the waveguide section connected to the antenna
or reflector must be able to rotate. We do this by using a section of round
waveguide called a rotating choke joint.
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