Applications
1) Trap resonance frequency measurement
To measure the resonant frequency of an antenna trap, first disconnect the trap from the antenna. Construct a one turn loop of wire of diameter slightly larger than the diameter of the trap and connect to the antenna analyzer.
Set the centre frequency and span width of the analyzer to cover the estimated resonant frequency.
Place the loop over the trap and look for the resonance. If the resonant dip is seen, go to marker mode and with the down arrow key, send the marker to the dip to find the frequency.
Using the up arrow key make the centre frequency of the analyzer the same frequency as the marker.
Return to parameter set mode by pressing the enter key to adjust span to see the resonance dip more clearly.
2) Adjustment of portable Antenna dimensions
You have just put together that temporary 80m inverted v antenna made out of some old PVC wire and a 6m fishing pole for example, and connected it to your radio, and the SWR is too high. Shorten or lengthen it - who knows!
Easy! - connect up the antenna analyzer and find the resonant frequency. If it is below the desired operating frequency then shorten it. If too high then lengthen it.
Antenna won't fit into available space - no problem - just wind up some of the wire to form temporary loading coils about three or more meters in from the ends of the antenna, and secure with PVC tape. Experiment with the coil dimensions and coil position to bring the antenna to resonance at the correct frequency.
At resonance the SWR is normally sufficiently low ( < 2:1 ) to be used with a radio without an ATU.
Ideally use an ATU to minimise SWR for greater operating frequency range and optimum performance.