a.
small dent in the waveguide will cause the energy to change from a TE mode to a TM mode.
b.
irregularity in the waveguide surface will cause reflections.
c.
ripple in the waveguide will cause skin-effect loss.
d.
rough surface will cause cutoff to occur too soon.
14.
Two waveguide sections that are mechanically connected by a choke joint also possess a good electrical
connection. This good electrical connection is realized because the
a.
depth of the choke joint groove is /2.
b.
depth of the choke joint groove is /4.
c.
distance from the inside wall of the waveguide to the bottom of the choke joint groove is /4.
d.
distance from the inside wall of the waveguide to the bottom of the choke joint groove is /2.
15.
A waveguide system is pressurized to
a.
keep the waveguide free of dust.
b.
allow the waveguide to handle more power.
c.
prevent loss of energy due to leaks in the waveguide.
d.
prevent the collapse of the waveguide at high altitudes.
16.
Circular and rectangular waveguides can be operated in either a TM mode or a TE mode. The field
configurations that represent operation in a TM mode are shown in figure 104 in the sketches labeled
a.
A and C.
c.
B and C.
b.
A and D.
d.
B and D.
17.
Most microwave RF systems contain an isolator, a mode filter, a mode launcher, and several directional
couplers. The purpose of the directional coupler is to
a.
remove a sample of the transmitted or received energy for test purposes.
b.
insure that only the desired mode is propagated through the waveguide.
c.
change the RF energy from one mode to another.
d.
reduce waveguide reflections.
344 L2
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