WAP54G - RF pattern & orientation

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Staring down at my WAP54G sitting on the floor with it's 2 antennas,
I was wondering about the pattern...

Is it using diversity - ping pong - so that both are not on at the same
time,
for either xmit/rcv ?
ie - each has it's own donut, and they both are not active at the same exact
time
therefore there is no addition/subtraction to the pattern.... circle oval -

SO - if it's upstairs, in a front bedroom,
then the donuts are equal and horizontal in plane....

What if we tilt the antennas, so the donut touches more of downstairs ?
And - thinking out loud - what about orientation vs the wall
The 2 antenna's along the wall - donuts going left & right along house
vs perpendicular to the wall ?

hmmm - gonna have to walk around (site survey) tomorrow with Netstumbler
and see if the orientation or tilting makes any differences in the actual
coverage.


--
----------------------------------
"If everything seems to be going well,
you have obviously overlooked something." - Steven Wright



Re: WAP54G - RF pattern & orientation
wrote:

~ Staring down at my WAP54G sitting on the floor with it's 2 antennas,
~ I was wondering about the pattern...

Think those are regular 2dBi omni "rubber duckies".

~ Is it using diversity - ping pong - so that both are not on at the same
~ time,
~ for either xmit/rcv ?
~ ie - each has it's own donut, and they both are not active at the same exact
~ time
~ therefore there is no addition/subtraction to the pattern.... circle oval -

Yeah, pretty sure that they are doing diversity.

~ SO - if it's upstairs, in a front bedroom,
~ then the donuts are equal and horizontal in plane....

Yep, with the antennas pointing vertically, then the fat part of the donut
is horizontal.

I have an old WAP54G and its antennas cover my somewhat sprawling
single story house just fine (through plaster-and-lathe interior walls, even.)

~ What if we tilt the antennas, so the donut touches more of downstairs ?
~ And - thinking out loud - what about orientation vs the wall
~ The 2 antenna's along the wall - donuts going left & right along house
~ vs perpendicular to the wall ?
~
~ hmmm - gonna have to walk around (site survey) tomorrow with Netstumbler
~ and see if the orientation or tilting makes any differences in the actual
~ coverage.

Yep, that's how you do it.

Have fun,

Aaron

Re: WAP54G - RF pattern & orientation
On Thu, 22 Jan 2009 20:31:31 -0600, "ps56k"

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It's pretty much a big fat donut.  Only one antenna is active at a
time, so it's the equivalent of a single 2dBi coaxial antenna, with
the added bonus of some pattern distortion produced by the 2nd
inactive antenna.

The construction is the same as the WAP11.  See:
<http://www.freeantennas.com/2400/
<http://www.freeantennas.com/2400/WAP-11/WAP-11.jpg
for some antenna patterns.

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Yes.  Only one antenna at a time.  However, there are some boxes with
2 antennas that always xmit on one of the antennas.  I'm not sure if
the WAP54G (what hardware version????) is among these.

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Sorta.  They are fairly independent patterns, but there is some
interaction.  You'll probably get more interaction from the WAP54G
shield, box, table, wall, and nearby metal objects.

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Sorta.  The pattern is a fairly fat donut.  The only nulls are going
to be directly above and below the unit.  The signal strengths in
other directions are more or less equal.

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That works if you tilt the "main" antenna instead of the "aux".  The
diversity system favors one antenna (main) over the other (aux).  It
only switches if there is a high error rate, such as when there are
reflections, nulls, noise, interference, or lack of signal.  Even if
the signal is marginal, it will continue to use the "main" antenna
before grudgingly switching to the "aux".  If it weren't for frequency
selective fading, you could probably live without the "aux" antenna.

I think (not sure) that looking at the back of the unit, the main
antenna is the left antenna.

Your homework for tonight:
<http://www.cisco.com/en/US/tech/tk722/tk809/technologies_tech_note09186a008019f646.shtml>
<http://www.commsdesign.com/design_corner/showArticle.jhtml?articleID=16501888
<http://www.commsdesign.com/design_corner/showArticle.jhtml?articleID=16500279

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I don't understand.  The bottom line is that you can't get more signal
in one direction, without stealing signal from another.  If you want
more coverage going up or down, you're going to lose some
horizontally.  Same with any other pattern modification.  Antennas
only redirect the RF.  

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

Re: WAP54G - RF pattern & orientation
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Correct.


Correct.


Correct.


Correct.


More like circle circle if the antenna is a 1/4 L, which most antennas
of this type are.

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Correct.


That's a good thing if you like better field strength downstairs. Just
remember to adjust the antenna(s) downstairs so that their donuts
points at eachother, so that they are alined for polarization.

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Clients that stands perpendicular to the donut so that the antenna phy
element is pointing directly to the client upstairs, that client will
suffer from such an orientation. This is a truth with modifications
because field pattern indoor when it comes to the dark side of the the
pattern is overthrown by reflections. The important thing is to make
sure your polarisation is alined. Outdoor (without reflections from
walls), if an omni antenna got vertical polarisation (antenna is
horizontal) with it's phy tip pointing to a client, and this client
got a horizontal polarization with phy element tip pointing up, you
got the worst case possible with a theoretically loss of 80dB. If one
is pointing horizontal and one is pointing vertical, but both are in
the same pane, the theoretically loss is 20dB. This is not something
you will measure indoors, and thats why it's very hard to give you any
reasonable advice how you should point your antennas other than they
all must be polaralized as close as possible to be in the same pane,
regardless of reflections, if you want to get the most field strength
you can.

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I bet you could see a difference of at least 10dB.


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