Re: Distributed capacitance effects inductor Q?
- From: "Andrew Holme" <andrew@xxxxxxxxxx>
- Date: Sun, 29 Apr 2007 11:56:32 +0100
"Bill Bowden" <wrongaddress@xxxxxxx> wrote in message
news:1177821718.856885.82580@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Does anyone know why the distributed winding capacitance of a loop
antenna, or any inductor, degrades the efficiency?
It would seem that a loop antenna with 100pF of winding capacitance in
parallel with a external capacitor of 200pF would resonate at the
same frequency as a antenna with no winding capacitance and a external
capacitor of 300pF, and perform just as well, but apparently that's
not the case.
The best explanation I got was that winding capacitance represents
'Low Q' and a external tuning capacitor represents 'High Q'
What is the difference between high and low Q, and why should a loop
antenna with no winding capacitance perform any better than one with
50% of the total capacitance in the windings? Where is the energy
loss?
Thanks,
-Bill
In a low-Q capacitor, energy is lost in the dielectric e.g. plastic
insulation. I imagine your external tuning capacitor is a high-quality
air-spaced type.
.
- References:
- Distributed capacitance effects inductor Q?
- From: Bill Bowden
- Distributed capacitance effects inductor Q?
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