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From: thad@cup.portal.com (Thad P Floryan)
Newsgroups: unix-pc.general,comp.sys.att
Subject: Re: microwaved people (was Brownouts, shorts, ...)
Message-ID: <37925@cup.portal.com>
Date: 12 Jan 91 14:12:27 GMT
References: <37881@cup.portal.com> <1761@mitisft.Convergent.COM>
Organization: The Portal System (TM)
Lines: 48

dold@mitisft.Convergent.COM (Clarence Dold) in <1761@mitisft.Convergent.COM>
writes:

	[...]
	When the radar was dismantled in 1976, we found flies inside the
	waveguide.  They were dead, but I imagine they starved.  They didn't
	look burned, even after 20 years of fairly constant high level radar
	exposure.
	[...]

Flies are smaller than 1/4 or 1/2 wavelength at "most" the frequencies at
which high power RADAR operates, so would not have been "cooked" resonantly.

If you think back of that chain-link fence which "sang" when hit by RADAR,
think of the length of each side of each "square" formed by the wire and you
can deduce the frequency (or harmonic thereof) at which the RADAR operated.

My reference to human eyeballs and testicles was based on an approx. 1GHz
frequency whose wavelenth "likes" objects that size.

Reason I bring up the above points is that once I had a "problem" with a
computer I designed in that one trace on the motherboard tended to resonate
and caused all sorts of weird problems that didn't occur on the prototype
which I hand-made; the guy who did the PC layout for Teflon-fiberglass simply
wasn't familiar with high-frequency considerations for layout.  Computers
using ECL or GaAs components are also susceptible to poor layout at the higher
frequencies.

I'll have to show-'n'-tell (via photos) some of my previous designs at even
higher freqs; the cases, traces, connectors, etc were all gold with ceramic,
sapphire or even diamond substrates, and, except for the occasional chip
capacitor, one wouldn't recognize ANY component on the microstrip "boards".
Designing with clocks far in excess of 1GHz often required empirical "tricks"
that mimic black magic and voodoo!  And the completed circuitry was nicknamed
"Tenement Housing" (picture that in your mind).

When people "boast" of 50 MHz-clocked computers today, I still think of that
as practically DC.  My lab operated with frequencies from "DC to daylight",
and the designator "THz" wasn't that uncommon.

And a short anecdote in closing: back when I was doing all this stuff, the
term "GHz" didn't even exist, we used "GC" or "GCPS" (Giga Cycles [Per Second])
.
When the standards committee wanted to honor Hertz with "Hz", we all protested
with a petition claiming they should instead honor Charles Proteus Steinmetz
and we'd then be able to continue using "CPS"!  :-)

Thad Floryan [ thad@cup.portal.com ]