The ARRL handbooks have these off and on -- no parameter computation, just
things that work. The copy I have at my desk is 1976 (don't ask me why --
in 1976 they'd given up on tubes and were barely figuring out how to make
decent solid-state circuits, but there you are). It has one for VHF/UHF,
it's on page 636, and it's made mostly from copper pipe from a plumbing
store.

The UHF experamenter's manual probably has something, too.

"Stéphane Rey" wrote in message
...
Hello,

I'm looking for documentation explaning how to design and built
directional
couplers for 2m and 70 cm application.

I've found a lot of links for the theory but nothing explaning how to
compute the parameters and built it .

Any suggestion appreciated

Thanks
Stephane, F1TJJ