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lower than -70dB. The derived S-parameter of M2 is the duplexer's insertion loss to
the transmit signal.
Chart 4-2: Typical curve of duplexer's LOW side, uncompensated cable loss
To get the insertion loss of the duplexer to the receiving signal, connect the
output port to ANT port, the input port to RX port and the dummy load to TX port.
After that, fine-tune the three screws on the RX side to get to M2's minimum,
commonly lower than -70dB. There we get the S-parameter of M1, which is the
insertion loss.
Switch the LO (Local Oscillation) mode, compare the minimum value of each curve,
and find out the lowest among. When adjusting both sides of the duplexer, different
OSL modes may need to be used.
Some duplexers' parameters of both sides can influence each other. In this case,
user may need to do the steps above again till the attenuation parameter is up to
-70dB.
Do not make the notch curve of the duplexer too sharp pointed at the bottom.
Through reducing the SPAN to 1MHz, observe the curve's bottom: it should be more
then 100KHz wide. If the curve is too sharp, its tip may drift out of the used frequency
once temperature or the matching of antennas has changed.
When there is conflict between the insertion loss and the attenuation, consider
the attenuation at RX side first. Properly lower repeater's transmission power to lower
the demand of isolation. In this case, keep in mind that "adjust TX toward inside,
adjust RX toward outside" to try to keep the balance between insertion loss and
isolation.
For coupling level, user can adjust the coupling bolt with the duplexer which is
adjusted by the screws. The other adjusting screws can be replaced with the longer
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