On Wed, 11 Dec 2002, Robert R. Ballecer, SJ wrote: > 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?
yes > If I rotate it 90 degrees > does that make it horizontally polarized? yes Is there a difference between > feeding from the top and the bottom? Left side or right? you want both antennas polarized the same direction, you may find that some antennas particularly dishes have about the same pattern horizontaly and vertically. > 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 > http://www.nodedb.com - Think globally, network locally > http://www.sydneywireless.com - Telecommunications Freedom > > 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> -- > JA> general wireless list, a bawug thing <http://www.bawug.org/> > JA> [un]subscribe: http://lists.bawug.org/mailman/listinfo/wireless > > > -- > general wireless list, a bawug thing <http://www.bawug.org/> > [un]subscribe: http://lists.bawug.org/mailman/listinfo/wireless > -- -------------------------------------------------------------------------- Joel Jaeggli Academic User Services [EMAIL PROTECTED] -- PGP Key Fingerprint: 1DE9 8FCA 51FB 4195 B42A 9C32 A30D 121E -- In Dr. Johnson's famous dictionary patriotism is defined as the last resort of the scoundrel. With all due respect to an enlightened but inferior lexicographer I beg to submit that it is the first. -- Ambrose Bierce, "The Devil's Dictionary" -- general wireless list, a bawug thing <http://www.bawug.org/> [un]subscribe: http://lists.bawug.org/mailman/listinfo/wireless
