The last time I did some searching on this, I figured out that many laptops are actually dual-pol. In realistic testing, I've taken the laptop to some of my vertical and horizontal AP's, turned it sideways, upside down, etc etc and really get no difference in db. Now, this is on my Dell Latitude with an integrated Intel card. I get better reception out of it than most other people I know for some reason. Have also done this with a PCMCIA card and have also not see much difference in reception.
I'm sure others may vary on this, but from what I've found, with Hotspot level access straight from the laptop there is no noticeable difference from either Polarity. -----Original Message----- From: wireless-boun...@wispa.org [mailto:wireless-boun...@wispa.org] On Behalf Of Tom DeReggi Sent: Thursday, April 30, 2009 1:21 PM To: WISPA General List Subject: [WISPA] WAN HotSpot and Polarity Over the years, there have been many theories and strategies regarding what polarity is best to use for various purposes. As an engineer, I as well have my theories. But, I wanted to get an updated opinion based on field trials of others, for the following application.... Application... 2.4Ghz WAN WIFI HotSpot Specs... 1) Average sub located within 100 yards to 1/2 mile. 2) Find and Subscribe by "Search for available Networks", via laptop's WIFI card. 3) If RF signal good enough to get a web splash screen to user, will display instruction for ordering higher gain antenna self-install kit for inside their window mount or balcony. 4) Access Point would likely use a sector panel (60 deg?), with an EIRP of 36db. The goal here is.... enabling residential users to find the ISP's AP on their own. So my questions are.... 1. If a Horizontally polarized antenna is used at the AP, Is it likely the consumer will equally be able to find your AP, compared to if it had been verical pol'd? The idea being, horizontal pol's noise floor is much lower in the particular area, and more likely ISP will avoid the noise from consumer APs that ship with vert pol antennas, where end users by default will stick the antennas straight up in Verticle pol position. 2. By the time the ISP's horizontal signal gets to the end user, is it received in multiple polarities, based on all the reflections in end users home and stuff? 3. Are laptop wifi cards typically "no polarity", and pick up Horizontal as good as verticle signals? 4. Laptops would appear to have Horizontal pol antennas in some cases, expecially if a PCMCIA card. Is this true? Or are most laptops starting to embed verticle pol antennas on the sides of screens? 5. Are End Users getting savy enough to move their laptop all around, when they first take it out of the box, to try and find Horizontal pol APs of ISPs Hotspots? In summary.... If doing Hotspot WAN deployment, and Verticle noise is significantly higher, will an ISP be doing a smart thing putting their sector on Horiz pol to avoid noise, or shooting themself in the foot because they'll be sending a signal cross pol to the average end user's verticle pol's Wifi card, taking a 20db hit off the bat? Sure.... Horizontal will be better, if the the consumer gets a professional install, or learns to put an external horizontal pol antenna on their laptop or PC. But most people may not know to do that, by default, for hotspot self subscription. (PS. recognize could use dual pol or 45deg off pol, but purposely avoiding that, to try not to interfere with others, to enable more people to play in the same spectrum) What have other's found? Tom DeReggi RapidDSL & Wireless, Inc IntAirNet- Fixed Wireless Broadband ----- Original Message ----- From: "George Rogato" <wi...@oregonfast.net> To: "WISPA General List" <wireless@wispa.org> Sent: Wednesday, April 29, 2009 8:27 PM Subject: Re: [WISPA] RB333/433 eliminating self-interference test > Tom DeReggi wrote: >> Good point but..... the problem went away when the mcpi cards each had >> their own SBC/Case, this would infer card to card or pigtail to pigtail >> interference, since in all cases the dummy load was outside the cases, >> from what it sounds like. >> >> I guess that should be clarified.... >> >> Kurt, when you tested with teh RB600 and 3 cards on the adjacent slots, >> was the RB600 also in a case with the holes metal taped? >> >> >> Tom DeReggi >> RapidDSL & Wireless, Inc >> IntAirNet- Fixed Wireless Broadband >> >> >> > > Question I have that should debunk that theory that cards in close > proximity interfere with each other. Why do the cards not interfere with > each other when there is additional gain antennas hooked on to them? > > You would think there would be even more self interference with high > gain antennas than with no antennas.... > > > > ---------------------------------------------------------------------------- ---- > WISPA Wants You! Join today! > http://signup.wispa.org/ > ---------------------------------------------------------------------------- ---- > > WISPA Wireless List: wireless@wispa.org > > Subscribe/Unsubscribe: > http://lists.wispa.org/mailman/listinfo/wireless > > Archives: http://lists.wispa.org/pipermail/wireless/ ---------------------------------------------------------------------------- ---- WISPA Wants You! 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