Page
56
Shorted
Quarter-Wave
Lines
Use the Dip Meter in
the
injection
mode. Couple
to
open wire
lines
as
shown in
Figure
3-8, and
to
coaxial lines
as shown in Figure 3-9. As
you adjust
the lines
for correct
length, temporarily install
the connectors that will be fitted
to
the
lines upon completion. Roughly
calculate the frequency
of the line. Resonant
points can be found
at three
times
the quarter-wave lengths, five
times the
quarter-wave length, and
so
on.
Open Quarter-Wave
Lines
Connect
a
short
at one end of the line, then
measure as
for
the shorted line.
Because
of
the length of the shorting line,
a
slight
error will be introduced,
depending on the line spacing.
The closer the spacing, the less error will be
encountered.
If the line is coaxial, the
short at the
open
end should be
as
small
as
possible
between
the shield and the inner conductor. Include
the
fittings
in your
measurements. After you make
the measurements, remove the short from the
cable.
Shorted Half-Wave
Lines
Use
the Dip Meter
in the injection
mode.
Couple
at the center of
the line
as
shown
in Figure
3-10. For
coaxial lines,
measure
as
for
a
quarter-wave
shorted
line
at half the calculated
frequency.
A resonant
frequency
determined in
this
manner
must be multiplied
by 2
for
the half-wave
shorted line.
SHORTING
Figure 3-8
SHORTING
Figure
3-9
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