Re: wrt54 antennas

On Tue, 22 Jul 2008 15:27:51 -0700 (PDT), jimmie68@xxxxxxxxx wrote:

Thanks Jeff, I am guessing that the traces on the board may form a
type of diplexer.

Nope. It's a diversity switch. If you look carefully, there's a 6
lead chip sitting at the junction of the two i/o ports. The chip does
the switching.

If this is the case leaving one antenna disconnected
and the port unterminated would defeat the operation of the diplexer.
In this case one antenna connected to one port would work as well as
connecting it to the other.

Not exactly. The port with the long coax cable (aux) has a bit of
extra loss in the cable and exhibits perhaps 0.5dB more loss. Not
worth worrying about unless you're trying to squeeze every last dB out
of the system.

This would explain my experience of having
the unit work equally well with 1 antenna on either port. Having 1 or
2 antennas woud probably make little difference if ther is not a
multipath issue

Read the Cisco article. The problem is when you have two different
types of antennas. It's quite possible that the wrong antenna will
hear the signal first. The diversity algorithm doesn't continuously
test for the best signal. If it hears something on the FIRST antenna
that hears a signal, it could easily just sit there forever. The only
justification for switching antennas is if there is a signal loss, or
a rather high bit error rate. If you're planning to use just one
antenna, you should disable the diversity switch in firmware.

--
Jeff Liebermann jeffl@xxxxxxxxxx
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
.

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