You already sound like an expert. So, the obvious question I have is - why do
you want to know the precise voltage? Sounds like an academic exercise. SRI,
I got tired of academics after being graduated from college with triple major
physics, chemistry and math.
73, Keith NM5G
On Tuesday, October 4, 2022 at 07:06:02 PM CDT, Dennis OConnor via
TowerTalk <towertalk@contesting.com> wrote:
Some wild speculation posted here.
Do I know what the voltage is at the tip for a 1500w PEP drive? Nope.I'm just a
brain dead old ham.
What I know is that the voltage is not "infinite because the current flow is
zero", as postulated..The current flow is not zero for more than one
reason..There is coupling from tip to tip. Coupling from tip(s) to
ground.Coupling from tip(s) to feed line.And probably other couplings.
So there will be current flow - even if far down in magnitude compared to the
radiated power.
We can only discuss the magnitude and phase angle of I.
There is also a reflection at the tip and a return wave front traveling from
tip back to source. i.e. current flow.A dip into Reflections III (RIP Walt)
will give you a thorough discussion of this and the difference between the
reflected standing wave of a short versus the reflected standing wave of an
open. And this can be measured through observing the position of the standing
wave.
I know the forward traveling wave on the antenna has not radiated all of its
power at the quarter wave point from the feed line.If it had radiated all its
power by then and reached zero voltage with zero current flow then an End Fed
Half Wave, EDZ, Bazooka and other abominations, would be a total waste of
wire/aluminum. The full wave loop antenna would not work.
I know that the ends of a dipole bite like hell leaving a burnt trench in a
finger. I know that a dipole fed with 1500 watts requires a good insulator. on
the ends to keep[ from. I know that the end of an EFHW and other long
(relative to wavelength) radiators need a good insulator.
Now, the experts can chime in.
Doc / k8do
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