The technique is described in Agilent AN 1287-8
The dips in the Time domain represent the resonators in the filter, S11 from one
end of the filter and S22 from the other. TDR allows you to see
the results of adjusting each resonator fairly independently of the others.
The aim is to increase the dips as much as you can. The peaks are related to
the inter resonator coupling. For a full explanation you need to read the Appnote.
As you can see from the frequency domain plot my efforts were not perfect
but I suspect practice will make perfect. The tune elements were 6 mm brass
studding and these were not the easiest thing to adjust. After I had done the
measurement I got a warning saying the calibration had been aborted. I had been
at it for about 30 mins and was getting cold, there is no heating in my workshop.
I will however try again. The filter is adequate for my 70 cms DATV station.