Hi Steve,

wrote in message
oups.com...
Don't think of these things as capacitors. They are really a version
of an open-ended quarter-wave transmission line stub.

Ah, thanks, I didn't realize people really were treating them as being
distributed instead of lump! (Since using copper pours as lumped capacitors
is certainly reasonable at lower frequencies.)

A search on "radial stub" is likely to turn up more info (though I
haven't tried it).

The first hit is pretty good (now that you're given me the correct search
term) -- the Microwaves 101 web site,
http://www.microwaves101.com/encyclo...uarterwave.cfm.

---Joel