Jack Twilley wrote:
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I'm interested in experimenting with phased arrays, but I can't find
any variable delay lines. I don't want coils of transmission line --
what I'd like is a little widget that can be tweaked to change the
amount of delay, but I don't see any of that for analog stuff like
transmission lines, just digital stuff like TTL logic. Help?

We meet in the oddest places, Jack, and this one's as odd as any. ;=)

For receiving, you could use voltage-biased varicaps; I know that lots
of VCRs use delay lines in which the variable elements are varicaps,
and the first such I encountered was an Ampex FR-900, back in 1966.
Linearity could be a problem, of course, so you might have to have
a DAC doing the biasing based on table lookup of the desired delay.

For transmitting, I think even the military use lots of coils of
transmission line, though I'm not privy to the innards of the
modern stuff. Scientific American had an article on phased-array
rigs in Feb. 1985; your library probably has a copy.

--
Mike Andrews

Tired old sysadmin since 1964