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Re: Vf,Zo,R,G,L,C.....
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> From: Tesla List <tesla-at-pupman-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: Re: Vf,Zo,R,G,L,C.....
> Date: Wednesday, December 30, 1998 8:49 PM
>
> Original Poster: Terry Fritz <twf-at-verinet-dot-com>
>
>
> I tested my coil WITH the top load in place using a <1 ohm output Z
generator:
>
> Fo = 111.6kHz Very strong.
> F(3/2) = 322.6kHz Pretty good signal.
> Then there were two very small 488 and 650 kHz bumps. Like 4Fo and 6Fo
???
>
> I wonder if the losses get very dramatic at higher frequencies???
Maybe the coil and top load is getting to be a better antenna??? As the
wavelength gets shorter, the radiation resistance (that is, that which
represents the radiated power from your system) gets higher, and would
start to be bigger fraction of the total losses.
For instance, a regular old wire dipole at resonance doesn't have a
particularly high Q (say, in the area of 10-20). But one of those little
loop antennas (a single turn of copper or aluminum about 1 meter in
diameter with a parallel variable cap for tuning) has a Q up in the
hundreds or thousands. The dipole has a radiation resistance around 70
ohms, and a loss resistance of an ohm or so, so it radiates just about all
the power going in. The little high-Q loop has a radiation resistance of
less than a tenth of an ohm, and a loss resistance of a few tenths
comparable to that, so it radiates only a fraction of the power on the feed
line.
After all, that distributed LC system is kind of a terrible transmission
line and a terrible LC resonator.