In article ,
W5DXP wrote:

On Thursday, September 26, 2013 12:08:20 AM UTC-5, John S wrote:
Very short and it is highly inductive.
Longer is less inductive.

John, the inductive reactance of an ideal shorted stub is a tangent function
that increases from zero at zero length up to a maximum on the Smith Chart as
the length approaches 1/4WL (undefined at 1/4WL). The equivalent inductance
is proportional to the inductive reactance so - very short and it is slightly
inductive (low reactance). Longer is more inductive (up to 1/4WL).

Agreed. So the inductive susceptance of a short shorted stub will be
high, while the inductive susceptance of a longer (but less than a
quarter wavelength) shorted stub will be low. Put that longer stub in
parallel with a dipole a little bit shorter than a half wave long (and
thus with a small amount of capacitive reactance and a large amount of
capacitive susceptance) and the net result comes out capacitive. This is
what I meant when I said that a shorted stub a bit too long to resonate
the (too short) dipole makes the whole thing will come out capacitive,
whereas if the stub is a bit too short for resonance, the whole thing
will come out inductive.

David, VE7EZM and AF7BZ

--
David Ryeburn

To send e-mail, change "netz" to "net"