steveeh131047 wrote:

Steve, congratulations on your QST article.

Now I run out a couple of horizontal wires from where the top and
bottom of the coil were connected, and short them at the far end
thereby forming a short-circuit stub. That stub will insert some
"loading inductance" in place of the coil. How long do I need to make
the stub to bring the vertical back to resonance?

I would also ask the questions: How much delay is there through
a series stub? What is the phase shift through the stub measured
by using the current on this standing-wave antenna? See below.

I also find this picture helpful because I can visualize that,
although there must be forward and return waves on the stub, the net
current I would observe is a standing wave whose phase doesn't change
along the length of the stub.

Someone is likely to point out that if one uses a current probe
to observe the current, it looks like a sine wave, i.e. its
phase is obviously changing with time. The point is that the
phase changes very little with length.

What we must be careful to say is that the phase doesn't change,
RELATIVE TO THE SOURCE PHASE, along the length of the stub. Here's
what EZNEC says about the phase in a 1/4WL open-circuit stub.

EZNEC+ ver. 4.0
1/4WL open stub in free space 4/22/2009 7:08:09 AM
--------------- CURRENT DATA ---------------
Wire No. 2:
Segment Conn Magnitude (A.) Phase (Deg.)
1 W1E1 .99665 -0.25
2 .97169 -0.67
3 .92292 -1.01
4 .85155 -1.30
5 .75929 -1.53
6 .64841 -1.72
7 .52163 -1.86
8 .38205 -1.96
9 .23309 -2.03
10 Open .07839 -2.07

Only 2 degrees of current phase shift in 90 degrees of stub.
How can that current be used to calculate delay through the
stub?
--
73, Cecil, IEEE, OOTC, http://www.w5dxp.com