Re: air impedance
From: Mark Fergerson (nunya_at_biz.ness)
Date: 06/07/04
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Date: Mon, 07 Jun 2004 09:18:12 -0700
Wayne wrote:
> Hi,
>
> I would like to make a device to measure the impedance of the air.
> I use a ac current source, (i.e.1kHz) to pass through two electrode in a
> fix distance. What is the possible value of the impedance of the air?
The far-field characteristic electrical impedance of air
(at STP) between a pair of transmitting and receiving
antennas is damn close to 377 ohms, as has been stated.
But you've basically described a kind of capacitor or
transmission line which is a near field device, meaning it
introduces complicating effects related to conductor spacing
and shape that are large compared to operating wavelength
among other things; you can measure its impedance with an
impedance bridge (look up that term), but it won't be
anywhere near 377 ohms unless the spacing is _very_ large.
Exactly what are you trying to do, look for impedance
variations as you change the air composition, or what?
BTW, where did you find an AC _current_ source?
Mark L. Fergerson
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