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Re: "Background Impedance of Universe"



Original poster: Ed Phillips <evp@xxxxxxxxxxx>

"     I was at a convention and ended up in a lunchtime discussion about
the B-2 bomber. One person said, "The impedance across the wingspan is
133 ohms". Another nodded and said, "That's because that is the
background impedance of the universe.""

	Blather and nonsense.  The expression "impedance across the wingspan"
doesn't make any sense in connection with the B-2 (I've been working
with it off and on since 1981) or any other aircraft.  Never heard of
"the background impedance of the universe", but the characteristic
impedance of free space is 377 (actually 120 pi) ohms.

	If one were specifying impedance of an object it would be necessary to
specify the mode of excitation involved and, of course, the frequency at
which the impedance is specified/measured.

	Sounds to me as if "one person" was talking through his hat.

Ed