Thanks Hans for taking the time to explain your methods. I have been doing a lot of testing with my Nano since I rec'd it at the end of August. The s1p formatted data has been most useful. I mainly measure impedance with the Nano. Then have done some impedance matching with good results giving me confidence that the measurements are pretty good. If you measure the Z to be matched, calculate a matching circuit, build it and the SWR is 1.0:1. I have not used SimSmith but have down loaded it. Years ago (some time in the early 90's possibly) I learned how to calculate the matching elements using an HP32S calculator that can store and run simple conversion formulas. I programmed in the series to parallel and parallel to series converters and with them it is possible to determine the L's and C's required. I bet SimSmith will make it even easier but right now I don't have the patience to sit still and figure out how to run it:)
In regard to the EFHW, the latest antenna craze, I wondered about the feed point Z of 67 feet of wire running from the ground up to a tree a steep angle (>45 degs for sure). I used an ancient General Radio GR-821A and did a direct measurement against a ground stake. The GR-821A can measure high impedances directly and it came up with 3700 to 3900 ohms shunted by about 8.5 pF at 7 MHz. I ran some tests at three locations that had I, am hoping, three different ground conductivities. The results were very close to each other. Using a transformer (2 turn primary and 18 turn secondary) I have great results on 40 and 20 meters.
Wish I could help out Chris with his questions. I have been where he is now. Takes some study and it will all fall into place. I am very cautious about making a solid conclusion due to common mode current on the outside of the coax line from measured impedances. One small change to how the transmssion line is routed and how long it is and what the mismatch at the antenna is will have an impact. What I have come to learn is that when the feed point impedance is low there is less common mode current and therefore less impact to the impedance measured. When the Z is high, then there is more of a tendency for current to flow on the coax braid and the impedance measured will be impacted. I have see the Z move by simply moving how the coax is placed or coiled up, etc..
73, Pete
