Hello OM's, hi Gil,

I'm trying to make an effective endfed antenna
for 20m band.
I don't know why everyone assume that 1/2WL endfed
wire has a 2450 ohm resistance?

I tried in different places with about 10m
long wire (1/2 wavelength at 14Mhz)
mounted vertically on a fishing rod from
fiberglass like this:



Each time the measurement (with my trusty NanoVNA-F, OSL Calibrated)
of the parallel resistance Rp (orange line)
at resonance (Xp = 0, blue line) is about 2100 ohms - as here:



note that at 7.2Mhz (1/4 WL at resonance Xp = 0)
the wire has a resistance Rp of about 120 ohms.

This leads me to think that the transformer for my antenna
for 20m should be 1:42 (not 1:49 or 1:64) !