RE: My external-antenna experiment on a Linksys wap/router failed!

Hrmmm, Haudy wasn't referring to that type of ground. Most
omni-directional antennas are called ground-plane antennas. Without a
proper ground-plane, your antenna can actually damage your radio, or
access point in this case.

It's unlikely that your AP suffered from your experiments, but it is
very likely that your output power would have been affected.

-Michael

-----Original Message-----
From: David Cook [mailto:DavidHCook@xxxxxxxxxxx] 
Sent: Thursday, October 30, 2003 5:52 AM
To: 'SeattleWireless Talk List'
Subject: RE: My external-antenna experiment on a Linksys wap/router
failed!


(The 'flattening' of the donut issue I specifically thought about.
The literature says that there is only 8-degrees of vertical, so
I specifically positioned it so the laptop would be oriented
correctly in the vertical plane.)


The issue of grounding could well be my problem.  (I've assumed
that since the outer coax shield attaches to the Linksys and
that the Linksys is plugged into standard wall outlet, then
I didn't need any additional grounding.)

Ok, let's assume I need to do something better for grounding.
There DOES happen to be a metal 'collar' about 2 or 3 inches
tall that would NORMALLY be in tight contact with the mounting
plate provided (which would be bolted in turn the metal pipe
on my outdoor antenna pole, which physically goes into the GROUND).

HOWEVER, for this experiment, the antenna was not mounted outdoors
to this antenna pole!  Instead, the antenna was hanging from a
piece of string tied to my ceiling fan in the room where the Linksys
is located.  So, bottom line is that the antenna was NOT grounded
(via this metal collar around the base) to ANYTHING AT ALL!

So, for sake of argument, what effect might LACK OF GROUNDING AT ALL
have on my experiment?  And, can someome suggest how I might rig
an acceptable ground to this antenna when I have it hanging from
my ceiling fan?  

(Or, maybe I ought to just go ahead and drill the hole
thru my wall of my house [as I've been planning to do] and re-run the
test with the antenna in its proposed final place, which would put
this grounding issue to rest.)

Thanks for all the inputs so far...they are excellent feedback.

Cheers...

                Dave


-----Original Message-----
From: talk-bounces@xxxxxxxxxxxxxxxxxxx
[mailto:talk-bounces@xxxxxxxxxxxxxxxxxxx]On Behalf Of Haudy Kazemi
Sent: October 30, 2003 08:06
To: SeattleWireless Talk List
Subject: Re: My external-antenna experiment on a Linksys wap/router
failed!


At 09:16 PM 10/29/2003 -0800, you wrote:
>
>On Oct 29, 2003, at 19:50, David Cook wrote:
>
>> I acquired a new Linksys BEFW11S4-V4, and loaded the
>> latest firmware into it (firmware v 1.45.7 ).  I also acquired
>> a 10-foot LMR-195 connecting cable and a HyperGain 10-dBi
>> Omni Antenna.
>
>Goto http://www.timesmicrowave.com/cgi-bin/calculate.pl and plug in the

>numbers.  10 feet of LMR-195 will give you ~2dB of attenuation at 
>2400Mhz.  With a 10dBi antenna you'll get ~8dBi, probably less if you 
>consider signal loss from the connector.

Some N connector specs I've read show .2 to .3 db loss per connector.
If
you switched to a 1.5ft LMR-195 pigtail and an 8.5ft LMR-400 extension,
assuming .3 db loss per connector, you would have about 2.1 db loss vs
2.6
beforehand.  Calculation based on LMR-195 @ .2db loss/foot, LMR-400 @
.067db loss/foot, .3 db loss per connector.  With more liberal values of
.18, .067, and .2, you'd see 1.6db loss for the link (1.5ft + 8.5ft
extension) vs. 2.2db using only LMR-195.

>What kind of omni is it? Did you play with the position?  Does the 
>antenna have sufficient grounding?

Be aware that high gain omnis 'compress' or 'flatten' the signal 'donut'
that emit, so if you're much above or below them you won't get the best
possible signal.  Also don't try to test it right up next to the
AP...leave
several feet spacing.

>I have a 5dBi mag mount antenna from Hyperlink, also using LMR-195.  
>I've found that there is a particular sweet spot on my car's roof that 
>gives me an extra 2dB of signal compared to other mounting locations.  
>Move the antenna around, if its a mag mount try sticking it on 
>something large and metal, see if it changes anything.
>
>-richard
>
>--
>Richard Lotz
>GPG Key:     http://students.washington.edu/rlotz/key.txt
>Fingerprint: 6BD7 C584 7DDC 43FD F0D4  87AB 5A8F 89D5 B3CC 9517
>
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