"k1drw" wrote in news:1167167054.718747.134870
@i12g2000cwa.googlegroups.com:

I have a question about AC Circuitry (as it relates to my antenna
system) where I cannot seem to arrive at an answer by reading reference
material:

The mechanics of current flow as it relates to a 1/4~ vertical
working against ground and separately, in comparison as it relates to
the dipole elements.

Is an AC circuit like DC, whereas there must be a ground return path
for a "flow" to happen ?

RE Dipole: If yes, then I get confused when thinking about ac current
flow relative to a dipole antenna. I can image current flow on the
center conductor side, since it seems the current +/- can keep going
back and forth from the transceiver to the end of the antenna element
(independent of the braid or other half side). But, it is hard to
understand how current can go back and forth on the braid side, since
it has a path to ground. Seems like on the braid side the current would
make its way down to the end of the dipole element and then start back,
but go right to the low impedance ground and be gone.

Vertical 1/4~: Again, here I image the ground side of the AC
circuit works as described above. But I read references to radials on
the ground side "collecting and returning ground currents" and that
confuses me. Returning currents to where ?, the current as pushed out
on the braid side seems to be where it was supposed to go - to ground.

Do both "legs" of AC current push out on the + and "pull" back on the -
, independent of 'ground' ?

I don't have an elec or engnr backgound so if you please to help me
understand, please try hard to keep it very basic. I just cannot use
math and AC formulas yet.

You can sometimes model an antenna as a set of lumped circuit constants,
but, in actual fact, at least one of these must represent the induced
impedance of the space around it. After all, that's what the antenna
really is--a device to couple energy from the feedline into the space
surrounding the antenna, where it will be lost to radiation.

I realize this isn't going to be that satisfactory an answer. Ground
currents do flow in radials and, because they (theoretically) flow equally
in opposite directions should add up to close to ZERO at the coax braid.

The current at the base of the antenna is high (the only thing keeping it
from trying to be a short circuit is the radiation resistance and any
resistive losses in the antenna itself). But it need not be matched by any
currents elsewhere. It IS "matched" by the induced radiation in free
space, though.

--
Dave Oldridge+
ICQ 1800667