View Full Version : Omni or Sectors
zrob_12
01-04-2009, 08:00 AM
I need to create a 360 degree antenna array for 900Mhz. I've already decided to go with horizontal polarization, but I don't know what type of base antenna setup to go with. What are the advantages and disadvantages of each:
1.) 11dbi omnidirectional antenna
2.) three 120 degree 12dbi sectors
I need to create a 360 degree antenna array for 900Mhz. I've already decided to go with horizontal polarization, but I don't know what type of base antenna setup to go with. What are the advantages and disadvantages of each:
1.) 11dbi omnidirectional antenna
2.) three 120 degree 12dbi sectors
1.) 11dbi omnidirectional antenna - One AP or 30 to 36 active users
2.) three 120 degree 12dbi sectors - Three Aps or three times as many users, three times the cost.
Info and pricing for 900 Meg HPOL antennas:
http://www.doubleradius.com/Products/Omni_2
http://www.doubleradius.com/Products/Sector_2
zrob_12
01-04-2009, 10:03 AM
Any other advantages or disadvantages?
They make HPOL omni antennas, and VPOL downtilt antennas...but they don't make HPOL downtilts.
So the advantage of a sector compared to an omni, you can have downtilt with the sector.
Here's a spread sheet I created some time ago.
http://telecomanddata.com/WiFi_downtilt.pdf
zrob_12
01-04-2009, 01:40 PM
Cool, anyway you can post the file in excel format or send to me?
You should be able to recreate it from PDF, just copy the formulas to correct cell and add the "=" sign in front of them.
jcremin
01-04-2009, 05:57 PM
I have 4 towers with 120 degree 12dbi horizontal sectors, and one with an 11db horizontal omni. I'm planning on replacing the omni with sectors eventually because it just doesn't perform as well due to the increased noise it picks up from every direction.
The biggest downside to sectors (other than the cost) is the available frequencies for 900mhz. I usually only have 2 clean frequencies when using 5mhz channels. I have found that two 120 degree sectors pointed in opposite directions works well for me. I don't really need all 3 as enough signal comes off the sides.
