[SI-LIST] Re: SMA connector or 2.9mm connector?
- From: <Wolfgang.Maichen@xxxxxxxxxxxx>
- To: <scott@xxxxxxxxxxxxx>, <swagguy09@xxxxxxxxx>
- Date: Wed, 13 Jun 2012 13:32:31 +0000
Hello Ming,
as Scott said, 2.92mm connectors have much tighter tolerances and offer higher
bandwidth than typical SMA connectors. As usual this comes with some tradeoffs
- they are much more expensive, and at the same time more fragile (dielectric
standoffs, vs. solid dielectric for SMAs); be careful when mating SMA to
2.92mm, while officially compatible you can easily kill the 2.92 connector with
a cheap SMA that has large mechanical tolerances. The real challenge is to get
the specified bandwidth onto the board, and the connector is only one part of
the equation here. Landing pattern, launch area/tapering, ground return each
have huge influence. A sub-optimal design in these areas can quickly negate the
bandwidth advantages of a 2.92mm connector, so you end up with an expensive
board without the benefit of higher performance.
I had good success with 2.92mm connectors from Southwest Microwave (one nice
feature being that they aren't soldered to the board, thus you can easily
re-use them on your next project and save a lot of money that way). They have
reference launch drawings available. For SMA, Rosenberger has some
high-performance models that performed to well over 20 GHz on my boards, and
while not cheap for SMA the cost was still much lower than the SW Microwave
2.92mm ones. On the downside, these are soldered down (center connector only),
but can be re-used with some skill in desoldering (hot air solder station).
Regards,
Wolfgang
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of Scott McMorrow
Sent: Wednesday, June 13, 2012 3:15 PM
To: swagguy09@xxxxxxxxx
Cc: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: SMA connector or 2.9mm connector?
Ming
It depends on the connector. standard SMA connectors are designed to have
a bandwidth of 18 GHZ. superSMA connectors have a bandwidth in excess of
25 GHZ, some of which up to about 32 GHz. 2.92 mm connectors have a
guaranteed bandwidth of 40 GHz.
Depending on what you are doing, I would generally recommend a 2.92
On Mon, Jun 11, 2012 at 9:05 PM, Ming Li <swagguy09@xxxxxxxxx> wrote:
> Hi, experts,
> We are designing test boards for 10Gbps per channel application and we are
> thinking about using either SMA connector or 2.9mm connector on the test
> boards? Can anyone tell us the detailed difference between SMA connector
> and 2.9mm connector?
>
> Thanks a lot.
>
> Regards,
> Ming Li
>
>
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--
Scott McMorrow
Teraspeed Consulting Group LLC
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