[Prev][Next][Index][Thread]
Re: RF biological hazards? (fwd)
---------- Forwarded message ----------
Date: Tue, 5 May 1998 16:14:57 -0700
From: Jim Lux <jimlux-at-earthlink-dot-net>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: RF biological hazards? (fwd)
> ---------- Forwarded message ----------
> Date: Wed, 6 May 1998 09:08:56 +1200
> From: Malcolm Watts <MALCOLM-at-directorate.wnp.ac.nz>
> To: Tesla List <tesla-at-pupman-dot-com>
> Subject: Re: RF biological hazards? (fwd)
>
> Hi Jim,
> I would describe the resonator as a monopole with a ground
> reflection.
>
> Malcolm
>
As would I, but I was looking for the quick and dirty approximation.
Assuming a perfectly conductive ground (!) and the bottom of the coil
sitting on the ground (!), then, it would look like a dipole of twice the
length of the monopole. My assumption for C would probably be the same (the
toroid top load formula probably accounts for the image), the assumption
for L was based on the resonant frequency, and would stay the same.
Given lossy earth, a significant amount of the power is going into heating
up the image. Interestingly, when you are in the near field, you aren't
doing much radiating, just swapping energy between the H and E fields.
In any case, the calculations should be good to an order of magnitude,
which will help determine if you are cooking yourself and the audience. We
won't even get into Part 15 compliance (most amateur built TC's would be
exempt anyway, under 15.23) or CISPR/CE.
> > Date: Tue, 5 May 1998 11:56:17 -0700
> > From: Jim Lux <jimlux-at-earthlink-dot-net>
> > To: Tesla List <tesla-at-pupman-dot-com>
> > Subject: Re: RF biological hazards? (fwd)
> >
> > Here is a quick calculation of expected electric and magnetic fields,
> > assuming the tesla coil is a "short" dipole (that is, it is much
shorter
> > than a wavelength). I calculated based on a total coil height of 1
meter,
> > with the secondary C of 40 pF and secondary L of 63 mH, for a resonant
> > frequency of 100 kHz. Further, I assumed the max secondary voltage was
1
> > megavolt. The calculated impedance of the coil is about 40K ohms (=
> > sqrt(L/C))
> <snip>
>