I have seen these antennas as well. One of my coworkers is into Ham
radio, and designed a set of tunable magnetic antennas for his
walkie-talkies. The antenna was much smaller than the standard antenna,
and gave very good performance, though it had a rather different field
shape than the traditional antenna. Basically, it was a short curl of
copper; you would never guess what it was by just looking at it.
On Saturday, September 20, 2003, at 08:27 AM, Paul Hardy wrote:
>
>> news.com takes it seriously....=20
>> http://news.com.com/2100-1039_3-5079564.html
>
> The concept is sound, but the news.com.com report is shallow enough to
> =
> be
> baloney. The concept of radiating power in this manner is not new. The
> "antenna" is, I would guess, an inefficient high-frequency transformer
> =
> with
> a carefully-designed air gap. I did some design work many years ago =
> with
> respect to storing energy that could be retrieved when the field =
> collapsed.
> We built an efficient power supply for a new type of movie theater
> lamp. =
> At
> the time, the competing products had to be lifted into place by crane,
> whereas ours could be delivered by one person. Our downside was that
> the
> failure mode was inappropriate: it was "fail stupidly dangerous", in =
> that if
> power was lost there was a huge amount of stored energy just waiting to
> re-saturate any ferromagnetic cores and PCB traces that weren't totally
> straight in the next 1/400th seconds.
>
> But, we did notice that extremely simple headphone-like equipment (if =
> you
> remember that telephone handsets used to consist of a capsule of
> loosely-packed granules) gave us a very good indication of how well the
> device was operating at that time, and at a substantial range. Mind
> you,
> people with bad fillings and scraps of foil from chocolate bars
> embedded =
> in
> their teeth were equally accurate guides.
>
> So I'd guess this is an analog rather than a digital transmission =
> medium.
> You can do a lot with a 0.4mm gap in a high-frequency transformer.
>
>
> This mail was sent to address EricHildum@earthlink.net
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Received on Sat Sep 20 19:07:03 2003