welcome to the foggy world of advertised antenna properties. i would guess
that in the 802.11 stuff there is probably just as little control over
quotes of antenna gains, measurement methods, etc as there is an amateur
antennas... this is why for a long time the arrl refused to print antenna
gain numbers.

wrote in message
oups.com...
Hello,

Can someone tell me what type of electical length does 802.11 antennas
(lambda/2, lambda/4, etc) have? The 2.4GHz has 12.5cm wavelength but
none of the rubber duck antennas that come with the wirless router have
a length of 12.5cm, 6.25cm, or 3.125cm, etc.

I recently purchased a 9dBi antenna to replace the 2.2dBi stock rubber
ducks. It also does not appear to measure in any n*lambda/4 lengths.
What puzzles me is that an outdoor $200 antenna of 3 foot long and a
$60 antenna of slightly less than 1 ft both have about the same gain.

And before the purchase I have tried to make a few higher gain antennas
out of a wire coat hanger in n*lambda/4 lengths but they don't have
much of an impact in signal strength. Why?

I did an antenna course years ago and remember the gain of a monopole
is related to its radiation resistance, which is proportional to
n*lambda/4 from what I can recall.

Thanks!