I'd argue the largest reason for downtilt is to prevent interference with a far out cell site. Even with 5.8 I've had sectors interfere with other sectors 25 miles away,without downtilt. The problem is that downtilt can also cause more multi-path if shooting into urban concrete instead of rural dirt. Sometimes not having downtilt can result in a better quality link, believe it or not. But whats important is having the flexibilty to point the antenna the way you need to point when you need to. You dont always know in advance what is finally needed. One can only engineer and predict the appropriate downtilt, but predictions dont always come true.
Tom DeReggi RapidDSL & Wireless, Inc IntAirNet- Fixed Wireless Broadband ----- Original Message ----- From: "Lawrence E. Bakst" <m...@iridescent.org> To: "WISPA General List" <wireless@wispa.org> Sent: Monday, March 29, 2010 5:50 PM Subject: Re: [WISPA] Ubiquiti Sector Tilt angle > Technically speaking you're wrong. The highest gain area of a sector > antenna is the center point between the horizontal and vertical spreads. > If you don't downtilt you are sending the strongest part of the signal > parallel to the horizon. Why would you ever want to do that? The whole > reason you downtilt is to get the strongest signal pointed to the area you > want. > > Figuring this out takes some basic trig calcs using the tangent function. > > No one has asked the most important questions you need to know when > calculating downtilt: > > 1. How high up is the sector antenna? > > 2. How far out or in what range near to far do you want the sweet spot? > > 3. How close in to the tower do you need service? > > #2 and #3 can conflict with each other and you may have to make a > tradeoff. > > leb > > At 2:22 PM -0400 3/29/10, Faisal Imtiaz wrote: >>..... Technically speaking.. if you are not concerned about dealing with >>'near' customers.... less than 1 or 2 miles... then you can pretty much >>leave the sectors at '0' tilt.. and you have coverage to the horizon.... >> >>The built-in electrical down-tilt typically throws folks off...... only >>becomes a factor if you are needing to down tilt for near customers.. >> >>Faisal. >> >>On 3/29/2010 1:36 PM, Robert West wrote: >>> I'm having a heck of a time with the large UBNT sectors getting the tilt >>> angle to jive. With the smaller sectors, they behave perfectly and go >>> right >>> where the calculations say they will however, with the larger ones, >>> nothing >>> I do other than have someone 10 miles out with a CPE check levels while >>> I >>> tilt up and down seems to be good. I REALLY don't want to have to do >>> that >>> with all of them... >>> >>> >>> >>> Anyone having any success or insight with the proper tilt of these >>> things? >>> Using the 120 degree 5GHz flavors. >>> >>> >>> >>> Thanks! >>> >>> >>> >>> Robert West >>> >>> Just Micro Digital Services Inc. >>> >>> 740-335-7020 >>> >>> >>> >>> Logo5 >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> -------------------------------------------------------------------------------- >>> 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! 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/ > > > -- > l...@iridescent.org > > > > -------------------------------------------------------------------------------- > 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! 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/
