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Re: Terry's New Plane Wave Antenna
Original poster: Terry Fritz <vardin@xxxxxxxxxxxxxxxxxxxxxxx>
At 11:16 AM 12/21/2005, you wrote:
"The capacitance between the coil and the antenna and the capacitive
load form a voltage divider. The voltage is directly proportional to
the coil's secondary voltage."
i think that what you said above is correct only in the vacuum, coz in
the air there are such things like "ion cloud", "rectification" and
maybe other even more funny stuff :-)
One should direct the arcs away from the antenna side of course
;-) The arcs toward the antenna would really mess up the antenna to
top terminal capacitance.
imo the charge in space between the toroid and antenna depends not
only from the toroid voltage (or secondary current) - changing of this
charge in time caused not only by the toroid voltage changing. so
even if we assume that the capacitance between the coil and the
antenna is always constant and totally independent from
processes/fields in its dielectric/interelectrode space, i think that
some high amplitude "peaks" that you see on waveforms are not the
peaks of the secondary voltage at all.
It would be easy to limit the bandwidth between say 10kHz and
10MHz. That would cur out a lot of other "noisy" voltages.
the most interesting - to see the voltage changing at the start (and
after) the discharge appears, but the antenna will work in its
worst way in this case - coz the discharge carries the area of the
strong field in its head. even if the discharge is not directed in the
antenna side - it should change the field configuration a lot anyway.
One could test for that with just a common metal wire shaped like a
streamer. That tends to increase the secondary capacitance buy the
usual 5 to 8%. But the system voltage would drop with this load. I
suppose one could "calibrate" the antenna with a wire streamer
simulator too... One could also slowly increase the coil's power
looking for odd jumps in the signal that really should not be there.
imo this antenna can`t be used for any measurements - only for
observing waveforms, and even then with some restrictions. but
waveforms of what? indeed not of the secondary voltage itself, but
summ of it with voltage changes caused by other processes.
It is a question of accuracy. I think the antenna does really well
compared to the next best thing, which does not seem to exist ;-))
ready for the bricks :-)
If you know how to do it better, do it!
Let the bass kick! =:-D
> Original poster: Terry Fritz <vardin@xxxxxxxxxxxxxxxxxxxxxxx>
> The files you mention are up to date. The antenna will work with any
> scope. The antenna's ground plane is grounded through the cable to
> the scope chassis.