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Re: Terry's New Plane Wave Antenna



Original poster: "Gerry  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>


Original poster: "Dmitry (father dest)" <dest@xxxxxxxxxxx>

> Original poster: "Gerry  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>

>> >   Seems
>> > like calibrating at NST voltages with 60 Hz would work just fine if
>> > streamers and corona did not happen to distort the e-field from what
>> > exist at 60 Hz. Not sure about this so please comment.
>>
>>i`m not sure too, but it appears to me that much stronger fields
>>(working coil) should have noticeably different configuration than
>>weaker ones (nst), coz they must interact with surroundings far more.

> I too believe that higher voltages result in higher fields that
> interact with surroundings far more.  If, however, the effect remains
> linear, then things should scale.  It is the non linear effects that
> I worry about.

interaction means more distortion, so when i`ve said "noticeably
different configuration" i meant non linearity.

OK



> I'm not sure what you mean by "flat top".  My concern is lingering
> reflections affecting measurements.  If both ends are unterminated
> then reflections can linger for a "long time"  Every transition can
> initiate a series of reflections so if they dont die quickly, the
> voltage measured can include a lot of "history".

Terry said, that the source end is terminated, so "That damps the
system (Q=0.7071..) so it does not ring or distort at the frequencies
we are working in.". btw Terry - why Q=0.707, why not Q=1?

but if Terry is right, then you can kill Blumlien effect just by
connecting 50 ohm in series with output of unballasted pig?

Terry's antenna has a 50 ohm resister in series with the coax at the antenna end. This resister connects to the capacitor divider. The termination is only effective above frequencies that the capacitor divider thevenin capacitance interacts with the 50 ohms (really 50 ohm resister is series with 50 ohm coax). If you thevenize the capacitor divider (20 nf in parallel with say 1 pf) you have a pole associated with equivalent RC combo with a frequency around 80KHz. Above this frequency, the coax is effectively terminated. Below this frequency, the termination tends toward open circuit. So in the frequency range of DC to 80KHz (lets say) the termination at both ends is not good. Granted the rise time of a particular frequency in this band is slower than the round trip propagation time. The real issue, I believe, is how long does it take for the multiple reflections from one transition to die out. Given multiple transitions, there could be many reflections continuing from previous transitions and measurement errors could occur. How significant this error is I dont know. Spice shows an effect that could be attributed to this effect that could affect the transient response of the measurement.

Gerry R