Inductance (fwd) [correction]
From: Antonio C. M. de Queiroz [SMTP:acmq-at-compuland-dot-com.br]
Sent: Thursday, April 09, 1998 1:56 AM
To: Tesla List
Subject: Re: Inductance (fwd) [correction]
Malcolm Watts wrote:
> From: Malcolm Watts [SMTP:MALCOLM-at-directorate.wnp.ac.nz]
> Sent: Tuesday, April 07, 1998 3:34 PM
> To: Tesla List
> Subject: Re: Inductance (fwd) [correction]
> Antonio, all,
> Well, the coil has to be connected to a significant current sink at
> least. Certainly, it is easily shown that self resonance occurs at an
> entirely different and much higher frequency if the coil is not
> connected to something like this. We know Medhurst refuses to work
> for half wave coils.
I think that I agree. The LC model for a coil assumes that one side is
at low impedance and the other side at high impedance, as a transmission
line closed at one end and open at the other.
A half wave coil is open at both ends. Using the simple TEM transmission
line model, it should resonate at twice the resonant frequency predicted
by the LC model (but I think that it will resonate at a somewhat different
frequency, because the coil is not a TEM line. In my tests I measured a
significant difference to higher frequency).
So, I correct what I said: A coil alone in the outer space, without any
side connected to ground, would resonate as a half wave coil, at about
twice the frequency corresponding to the LC model prediction. If one
side is grounded, the LC model makes correct predictions.
Can someone post some experimental data about resonances, Ls, and Cs of
half wave coils to verify this?
Antonio Carlos M. de Queiroz