dansawyeror wrote:
I proceeded before reading this note. The procedure was to zero the
phase meter on an short and then to test the loaded 2m vertical. The
result was +10 dbm forward (before the 20 dbm pad) and -50 dbm
reflected. The coupler measures about -14 dbm. The total was about -60
dbm, with 34 db of that due to the pad and coupler. The net is -26 db
forward - reflected.

(The phase angle and reflected ware very touchy. It was almost
impossible to adjust by changing frequency. It was easier to 'adjust' it
by sitting very still and moving my arm.)

The antenna is a copy from the ARRL handbook. It is a 4 inch segment, a
1 inch long by 3/4 inch diameter 5 turn coil, and a 4 inch tip. It is
mounted over a 2 foot square aluminum plate. This antenna should have an
input impedance less then 20 Ohms.

How did you arrive at this figure? I wouldn't hazard a guess without
modeling it.

How can it measure very close to 50 Ohms?

1. Inductor loss.
2. Effect of finite size ground plane.
3. Coupling to feedline.
4. Measurement error.

Is there something wrong with
this analysis?

I don't know. What should the impedance really be?

Roy Lewallen, W7EL