Spatial diversity is primarily used to combat multi-path. If you have clear los, your chances of bad multi-path are fairly small and you probably won't see a lot of benefit. If you have a lot of objects between you and the tower that can cause reflections, then it will help more. Simple enough?
On Wed, Aug 26, 2015 at 10:19 AM, Adam Moffett <dmmoff...@gmail.com> wrote: > There are a couple of products out there selling 4x4 MIMO (Telrad is one, > but there are others). > > In Telrad's case, two of the chains have a time offset from the other two, > so you get two chains on each of two polarities. Their default antenna is > a single sector antenna with 4 N-connectors on it, so there's no > significant spacial diversity. In the past it's been suggested that we use > two dual pol sector antennas and space them 3 feet apart to get spacial > diversity. > > When I asked why they do the single antenna, a source at Telrad told me > that spacial diversity "only helps a little". The party selling us the two > panels considers it to add 6db when they run coverage projections. I > suspect any gain from spacial diversity is going to depend on a lot of > circumstances and I doubt it could be as simple as adding 6db. > > I'm wondering if anyone here has any opinions on the topic? Maybe even > facts :) > > (I'm sort of eyeballing a certain guy in Utah who designs antennas and > isn't trying to sell me anything.) >
