Re: NEC-LIST: Re: NEC-List Digest, Vol 3, Issue 15 Coil Loading

From: Chuck Counselman <ccc_at_email.domain.hidden>
Date: Tue, 08 Feb 2005 13:46:32 -0600

At 9:23 AM -0600 2/8/05, Mike Jacobs wrote:
>On the subject of coil Q, I have been working on a project that required
>...high-Q coils... and have looked at using NEC-4.1 for modeling
>air-core coils using a wire conductivity LD command to get a value
>for the loss in the coil....

For high Q, the turns of the coil must be closely spaced. The
thin-wire approximation (which treats current density as uniform
around the circumference of the wire) is not accurate in this case.
Yes, NEC-4.1 will calculate nearly the correct inductance in this
case. However, neither the resistance nor the "stray" capacitance
will be calculated accurately, because the current and charge density
are far from uniform around closely wound wires.

-Chuck W1HIS

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Received on Tue Feb 08 2005 - 19:46:53 EST

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