JAWUG

Ask your Questions here, and we'll answer them

Legend: Q = Question, A = Answer, O = Opinion

Q: Should you use omni directional antennas at all?

O1: Omnis are horrible things when it comes to use outdoors. Most people will use them because they're an easy solution for covering 360degrees, but there are a few things you'll have to keep in mind.
1) The range of an omni isn't as good as the range you'll get out of a directional of the same gain.
2) The more people you connect to an omni, the bigger the HiddenNode+ problem becomes.
3) You'll be picking up noise and interference from 360degree too!
See also OmnisAreBad.

Moral of the story, dont use omni's for point to point links. And if you absolutely have to cover 360degrees, consider going for a bunch of Sectorals (4 x 90degrees or 3 x 120degrees).
In response to {joey}: Ofcourse, use seperate radios for antennas. Anyone found using Splitters will be treated the same way as people found using amped omnis

O2: I disagree with the opinion, O1 above ({joey}).
In response to (1): That is the nature of RF, the greater the angular coverage, the lower the range. You don't always want longer range. There are times when a shorter, wider range is what is needed.
In response to (2): Agreed, but that holds for ANY antenna. However, the likelyhood of this happening may be greater with an omni.
In response to (3):This is not a well thought out argument. Remember that altough you are receiving only noise from a smaller degree, a directional antenna will amplify this noise proportionally and thus the overall noise floor will be the same. Unless, there are large point sources of noise that is, in which case a directional antenna can be better (if it points away) and worse (if it points in the direction of the noise source!).

In response to the moral of the story/opinion:
Agree with the 1st line, dont use omni's for point-to-point links, however, a bunch of sectors is NOT better for a 360 deg solution, unless you have indiviual radios for each sector! Your cable and connector losses needed to split a single radio will make it MUCH worse!

My moral of the story is, if you have people that want to connect from all directions and they don't live too far away (<3Km) and you don't have money to waste, then by all means, use an omni! If you have money to waste, buy three radios and a 120 degree sector for each one.