User Manual

Antenna Tuning
Figure 29:Antenna Adjustment Screw
Adjustment s crew
The center antenna always remains fixed in position and connected to the antenna-tuning device.
The other two antennas should be slightly loosened so they can be moved with relative ease but
do not move on their own (Figure 29)
The isolation should be checked as follows:
1. Adjust the position of the bottom antenna with respect to the center antenna.
2. Adjust the vertical position of the bottom antenna so that a minimum is seen on the
oscilloscope.
3. Repeat with the top antenna.
The central antenna remains fixed in position and the top and bottom antennas are moved,
one at a time, to adjust the isolation.
While the top antenna is connected to the oscilloscope the bottom antenna should remain
connected to the antenna connection board, and visa versa.
Note that the isolation adjustment process often requires repeating the procedure several times
between the top and center antennas and between the center and bottom antennas. This means
that it is normally more difficult to achieve good results of isolation between the center and bottom
antennas. Therefore, it is important to check and minimize the isolation between the center and
bottom antennas before moving to the top and center antennas. Typically, an isolation value equal
to or less than 100 mVpp should be obtained between the center and bottom antennas and also
between the top and center antennas.
6.4.2 Using an Impedance Analyzer
If an Impedance Analyzer is available, perform the same procedure as described for the Antenna
Tuning Kit.
December 2004 Revision 1.0 39/50