On 3/7/20 12:42 PM, Jim Brown wrote:
On 3/7/2020 11:47 AM, Richard (Rick) Karlquist wrote:
I notice that the 6 inch diameter 2 turn loops
have a free space electrical length of exactly
1 radian at 50 MHz. Is that just a coincidence,
or is that in some sense optimum?
It's a coincidence. I looked at Fair-Rite's data, noted above, wound
some chokes and measured, and liked what I saw.
Harold Wheeler
coined the term "radianlength" and noted that
it seems to be magic length where systems transition
from lumped element to distributed elements, etc.
It's like that old Tesla coil thing about the secondary winding wire
length needing to be 1/4 wavelength at the operating frequency. Indeed,
that is where many coils happen to wind up, but it's sort of a
coincidence, because the coils have similar length/diameter ratios and
number of turns.
There have been folks who have attempted to model a tesla coil as some
sort of slow wave structure (essentially a transmission line with a very
high L/C ratio, like that delay line coax with the spiral center
conductor), but lumped models work just as well.
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