Hi Tom, Call me naive...not quiet sure what you are asking. specifically...
We have a number of the smaller Ubiquiti Sectors in use.... Prior to your email it never occurred to me that I have to worry about cross pol rejection with MIMO antennas... But on the other hand I am also not trying to put 10miles link using those antennas.... All I can say they work perfectly fine.. :) Regards. Faisal Imtiaz Snappy Internet& Telecom 7266 SW 48 Street Miami, Fl 33155 Tel: 305 663 5518 x 232 Helpdesk: 305 663 5518 option 2 Email: [email protected] On 8/10/2010 7:32 PM, Tom DeReggi wrote: > The Ubiquiti dual pol antennas have been around for a while now. > Has anyone gained any real world testing results regarding difference in > performance for MIMO based on which antenna used. > > The two Ubiquiti sector types 16/17db versus 19/20db models have > signficantly different specs on Cross pol rejection. > As well, NanoStation makes a good 45 deg sector, at 14db, (14dbi + 22dbm = > Max EIRP 36db for PTMP) with a bit less cross pol rejection than the others. > > > From past experience, in any MIMO product in general, using PTP, I've > observed that maximizing the Cross pol isolation is very advantageous to > gain a highest performing links. > (so pols dont interfere with each other at high modulations). In general, > I'd get numbers like anything less than 35db isolation would result in > quality loss. > BUT... I've never tested with Ubiquiti yet. > > So my question here is.... Have people been successful using the smaller > 16/17db Sector antennas successfully with MIMO? > > I can do the math and RF engineering, and I can predict that the larger > 19/20 db antenna's have much better cross pol rejection, and combined with > the third party shield made for them, to increase Front to Back ratio > signficantly, they are an ideal choice for serious cell site deployments. > > But, for less critical smaller area deployments, I can see the adantage of > using the smaller antennas to save space vertically. > So just wondering what experience others are having with the 16/17db > Ubiquiti Sectors. To be clear, the "gain" of the antenna is NOT my concern > here. I interested in whether the Cross Pol rejection is good enough on > shorter sector antenna to gain good MIMO quality. > > Note: short antenna speced at 22db cross pol isolation, whereas taller > antenna speced at 28db cross pol. > > Tom DeReggi > RapidDSL& Wireless, Inc > IntAirNet- Fixed Wireless Broadband > > > ----- Original Message ----- > From: "Butch Evans"<[email protected]> > To: "WISPA General List"<[email protected]> > Sent: Tuesday, August 10, 2010 6:11 PM > Subject: Re: [WISPA] RB1100 > > > >> On Tue, 2010-08-10 at 16:48 -0400, Chuck Hogg wrote: >> >>> It's the same. All these distributors "NAME" their gear as their >>> own devices. One distributor will support you without the added >>> fees, and the other will charge you the fees. It's cheaper at Titan. >>> When I owned QuickLink Wireless, it was these types of things that >>> separated us from other distributors; how the customer was supported. >>> >> This is exactly the point I was making. Titan is a great company to >> work with (this is from my own experience). My company is good to work >> with as well, though I didn't mention that. There are several companies >> out there that sell this (and other) hardware. The only difference is >> the company you end up dealing with. For some, Dennis is their >> choice..there is NO "secret sauce" in the routers themselves. >> >> -- >> ******************************************************************** >> * Butch Evans * Professional Network Consultation* >> * http://www.butchevans.com/ * Network Engineering * >> * http://store.wispgear.net/ * Wired or Wireless Networks * >> * http://blog.butchevans.com/ * ImageStream, Mikrotik and MORE! * >> ******************************************************************** >> >> >> >> -------------------------------------------------------------------------------- >> WISPA Wants You! Join today! >> http://signup.wispa.org/ >> -------------------------------------------------------------------------------- >> >> WISPA Wireless List: [email protected] >> >> Subscribe/Unsubscribe: >> http://lists.wispa.org/mailman/listinfo/wireless >> >> Archives: http://lists.wispa.org/pipermail/wireless/ >> > > > -------------------------------------------------------------------------------- > WISPA Wants You! Join today! > http://signup.wispa.org/ > -------------------------------------------------------------------------------- > > WISPA Wireless List: [email protected] > > Subscribe/Unsubscribe: > http://lists.wispa.org/mailman/listinfo/wireless > > Archives: http://lists.wispa.org/pipermail/wireless/ > > -------------------------------------------------------------------------------- WISPA Wants You! 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