Re: Distributed capacitance effects Q?

On Sun, 29 Apr 2007 14:30:29 -0500, "amdx" <amdx@xxxxxxxxxxx> wrote:

Capacitance does not bring loss.

I'm not ready to give on that yet, but I could be convinced.
It seems I could add capacitors across turns of a coil and increase
circulating currents that would show as a lower Q. But I haven't
built a coil to test this.

Hi Mike,

This is then a characteristic of the Capacitor called D (dissipation).
Any increase in current tied to loss immediately goes to the bottom
line of resistance - it is a square law relationship, after all.

Loss ALWAYS resides in Resistance and nothing else.

I agree, X/R=Q Lower Q means more loss.
(let's not get into radiation resistance right now)

Why not? Small loops suffer by comparison, and multi-turn loops even
more so.

Proximity effect could cause all of the additional losses.
Or it might just be part of the additional losses.

For wire separations beyond 3 or 4 wire diameters, the increase in
skin effect is small. It might be noted that interwinding Capacitance
also falls.

Why is it that when you get near self resonance of a coil the Q gets lower?
Note; to help clearify my question,
( as you get nearer and nearer resonance the capacitor you are using to tune
the inductor is getting smaller and smaller, and closer to equalling the
self
capacitance of the inductor)

Again, the answer must reside in Resistance. There are many
characteristics (wavelength, solenoid diameter, length, pitch, wire
gauge, self-capacitance, distributed capacitance, balance,
connections, earth proximity, radiation resistance) being juggled with
small Loop antennas and some (even many) choices that can be made to
resonate the antenna do not lead to an efficient solution.

73's
Richard Clark, KB7QHC
.

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