1. To tune (match) the feeder line at the one side of feeder (ex. 50 Ohm) with vector Analyzer (there are two common types of LC matching cirtuinries below), the feeder this time is loaded with 50 Ohm resistance. (now load is feeder line, terminated with 50 Resistor)
2. To match the antenna with the second side of the feeder using a similar approach (now load is antenna)
So both sides of the feeder line ideally must be tuned.
Like easy guide how to tune feeder line to load using the Smith's diagram will put this picture from a very handy
There are several different possibilities to match, which are depend of start point on Smith's diagram. There are several pictures like guidelines below:
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