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Date:      Sun, 3 Apr 2005 12:34:39 +0930
From:      "Daniel O'Connor" <doconnor@gsoft.com.au>
To:        freebsd-hackers@freebsd.org
Subject:   Re: which Wifi cards can be used for a WAP?
Message-ID:  <200504031234.39665.doconnor@gsoft.com.au>
In-Reply-To: <20050402173304.GX44514@numachi.com>
References:  <20050402065052.GT44514@numachi.com> <20050402162842.GU44514@numachi.com> <20050402173304.GX44514@numachi.com>

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On Sun, 3 Apr 2005 03:03, Brian Reichert wrote:
> Some cards have an antenna built right onto the card, and others
> seem to come with a remote antenna that hangs off of a six-foot (or
> so) cable.
>
> The vendors' arguments for the cable arrangment is that it allows
> for a more optimal placement of the antenna, but other lore suggests
> that the cable itself introduces loss of signal.
>
> Does anyone have a concrete opinion on this, or can point me in the
> right direction for some research?

An onboard antenna will suck - if it's a Cardbus card it will be some dinky=
=20
PCB dipole with minimal gain (which you can't reorient for your environment=
).=20
If it's a PCI/mini-PCI card then it will be inside your PC and suck even mo=
re=20
so they need an external antenna. (And I've never seen a [mini-]PCI wireles=
s=20
card without an antenna connector).

Lots of cards have a diversity arrangement where they have 2 RF paths, 1 is=
 on=20
the PCB and the other goes to an external antenna port. If you plug in an=20
external antenna it will almost certainly get more gain and be used in=20
preference.=20

While cable loss can be an important factor it is usually not an issue if y=
ou=20
choose appropriate cabling and antennas. It may be a problem if you need to=
=20
do a long run (>20m) but that is pretty rare, and in that case you might wa=
nt=20
to consider relocating the box to be closer to the antenna (or using a USB=
=20
wireless interface :)

I would guess most vendors reasoning for not putting an external antenna=20
connector on a card is cost. Most people don't use them on Cardbus interfac=
es=20
and they cost a reasonable amount. On my (terribly ancient) DWL-650 card it=
=20
has PCB pads for a connector but it isn't used (the shell prevents it) but =
it=20
was fairly easy to modify the card to have an external connector. (YMMV,=20
fire/smoke warning etc)

=2D-=20
Daniel O'Connor software and network engineer
for Genesis Software - http://www.gsoft.com.au
"The nice thing about standards is that there
are so many of them to choose from."
  -- Andrew Tanenbaum
GPG Fingerprint - 5596 B766 97C0 0E94 4347 295E E593 DC20 7B3F CE8C

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