Ok,
I'm sure that I'm showing my "newbieness" here, but can y'all tell me a bit
about polarization?
Say I have two cantennas. The feeds are at the "bottom" side of the can.
Does this mean that it is vertically polarized? If I rotate it 90 degrees
does that make it horizontally polarized? Is there a difference between
feeding from the top and the bottom? Left side or right?
I know that I sound like the dumb kid in class, but please bear with me
here.
Peace,
Blackrobe
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED]]On Behalf Of evilbunny
Sent: Wednesday, December 11, 2002 3:31 PM
To: Jim Aspinwall
Cc: [EMAIL PROTECTED]
Subject: Re: [BAWUG] Re: Cross-Bay link
Hello Jim,
Tell that to the guys in Greece that managed to get links happening
between the canary islands :)
I've heard 130km from a consume guy that gave a talk out here a month
ago, and I saw an announcement for 70km a few months before that...
15dBm cards and 24dBi dishes... (no amps)
I know for sure 10km is more then possible, and at 11Mbits, using a
180 8 slot slotted wave guide and a cantenna...
across the bay here, across at least 1 runway at Sydney airport and
there is also something in the vicinity of 120 access points located
at Sydney airport...
I found horizontal polarisation to be a lot more effective then
vertical also...
--
Best regards,
evilbunny mailto:[EMAIL PROTECTED]
http://www.cacert.org - Free Security Certificates
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Thursday, December 12, 2002, 7:52:58 AM, you wrote:
JA> Concur with Tim's experience and the issues with doing this.
JA> Additionally, Sprint Broadband Wireless engineers told me they have
similar
JA> difficulties trans-Bay from San Bruno (near Sign Hill) to Berkeley,
JA> Oakland, etc. - visual line-of-site but several 'environmental' factors
JA> involved - Bay Bridge, the Bay (waves are highly variable reflectors),
the
JA> distance and the marine layer.
JA> Get two hams, two sets of 2.4 GHz gear with signal strength indications,
JA> coordinate antenna alignment live. What we need is a good 100-500mW CW
JA> beacon transmitter and a complimentary receiver with signal strength and
JA> Sinad readouts as a test set...hmmmm....
JA> SF-Berkeley is the toughest shot, over water with the Bay Bridge
clutter,
JA> etc. - the rest would be easier from hilltop levels, but from ground or
JA> even building top level - ooooooohhhh - tough call.
JA> Stretching a 300 meter technology at these power level out to 10-30 km
is
JA> asking a bit much no matter which antenna, etc. you're using.
JA> At 12:00 PM 12/11/2002, you wrote:
>> 1. Re: Cross-Bay link (Tim Pozar)
>>
>>Message: 1
>>Date: Tue, 10 Dec 2002 11:59:57 -0800
>>From: Tim Pozar <[EMAIL PROTECTED]>
>>To: "Robert R. Ballecer, SJ" <[EMAIL PROTECTED]>
>>Cc: [EMAIL PROTECTED]
>>Subject: Re: [BAWUG] Cross-Bay link
>>
>>On Sat, Dec 07, 2002 at 06:30:56PM -0800, Robert R. Ballecer, SJ wrote:
>> > Has anybody had experience with shooting 802.11b across the bay?
>> I ask
>> > because my organization has properties Fremont, Berkeley, San Jose,
Santa
>> > Clara (University), Los Gatos, Los Altos and San Francisco. Each
location
>> > is high enough to be able to "see" at least two of the other sites
>> through a
>> > telescope. There are not many practical uses for the link at the moment
>> > (each site already has broadband access) but it might be a nice project
for
>> > my free time.
>> >
>> > I was thinking about getting a few of those Senao 200mw cards and
>> use them
>> > in conjunction with some homebrew antennas. Anybody have the equations
I
>> > need to figure out how the distance will affect S/N? What says the FCC
>> about
>> > 200mw cards?
>>
>>We tried one 20 mile link with 250mW amplifiers from Sign Hill in
>>South San Francisco to a house in Hayward. The antennas were 24dBi
>>dishes. We were able to get both ends to associate and get some
>>data back and forth, but not consistently. You can see the path
>>profile at:
>>
>>
http://www.lns.com/projects/sunsetwireless/paths/Matt2SignHill.pdf
>>
>>Some of the problems we ran into was antenna alignment. 802.11
>>radios do not update C/N data fast enough and the data tends to
>>bounce around. We decided that in order to line up paths you really
>>need to use different transmission gear for antenna alignment such
>>as a carrier wave at the frequency you want and a spectrum analyzer.
>>This also helps as you really have a hard time tracking SS signals
>>on a spectrum analyzer.
>>
>>Of course there are a number of things you need to look at before
>>you get to this point. Looking through a telescope will pass some
>>some tests but you need to look at other things like "refraction"
>>and "fresnel zones" to insure that the data will get from one
>>transmitter to the other. I think there has been some discussion
>>on the list before in "engineering" paths. If not, I can put
>>together one.
>>
>>Tim
JA> --
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