Re: BNC for use at 11GHz ?

MarkAren wrote:
For years, I have been gently preaching that BNCs are only any use up
to 1GHz and if you want to go any higher use TNC for a similar
footprint.

Recently I tripped over http://www.amphenolconnex.com/products/bnc.asp
indicating that their BNCs are OK up to 11GHz.

They are playing fast and loose with the 11GHz figure. If you read down
in the actual specs they say that they only guarantee VSWR's below
1:1.3 (or 1:1.35) up to 4GHz.

I mean, a quarter-inch phone plug will let some signal through at some
horrendous SWR at 11GHz :-).

Any ideas where the 1GHz limit for BNCs might have arisen from ? I am
sure I have seen it numerous times in Ham Radio publications.

The limit depends on what SWR you're willing to take, and that depends
on power levels (transmitters) or noise figures (receivers) and cables
and gain budgets and a bunch of other things. Anybody telling you a
single number for a limit is putting a lot of stuff under the rug.

It's also true that if you do not do "officiial" crimps that your SWR's
are probably going to be way higher than the numbers on the spec
sheets. I think the 1GHz number is pessimistic for official crimps but
probably realistic for typical ham crimps. It's hopelessly optimistic
for say twist-on BNC's.

And note that many manufacturers carry cheapo grade connectors (e.g.
Amphenol RFX) as well as sometimes premium grade connectors that do
worse or better at higher GHz than the usual stuff at very different
price points.

Tim.

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