We are replacing an epmp 2K AP with a 3K AP, I was thinking about using two 65 degree antennas vs one 90 degree antenna. My question is sort of two fold. 1) I am assuming I would gain coverage area by having two antennas, but at what performance cost if any? 2) do I lose the advantage of MU MIMO? or ??? Thank you
We recently did some comparative testing between the original e3k 70deg? 4x4 OEM antenna w/BSA and the new RFE 90deg 4x4 horn array and found…
So first the good stuff…
- Provides a noticeable increase in gain (around 3dB on average) vs. the OEM antenna
- Can help push an SM up 1 modulation level if it was on the edge
- Provides a wider more consistent/predictable coverage area when compared to the OEM antenna
The not so good stuff…
- Is significantly heavier and more bulky then the panel antenna, more difficult to deploy. This is not an antenna that you want at the top of a small/skinny tower.
- Significantly more expensive than the panel antenna
- Requires a stand off to mount to tower, adds to time/expense/difficulty in deployment
These two items are a bit more fuzzy and results could possibly be tainted by the OEM antenna being mounted about 10’ higher on the tower above the 4x4 horn array…
- Seems to have trouble triggering MU-MIMO… tests needed to be run over and over to trigger MU-MIMO. SM’s that were triggerable on the OEM antenna are sometimes not triggerable on the 4x4 horn array
- While RSSI might be slightly better with the horn antenna, it might not result in meaningful throughput gains. When averaged both the OEM antenna and the 4x4 horn array produced similar speed test results
In conclusion…
I think it makes most sense for operators that are deploying this out of the box with a new radio. I don’t think it makes sense to swap out an existing OEM antenna for this. I think that operators that are used to horn antenna’s predictable coverage area and the ability to plan their deployments around this will most likely enjoy this antenna the most.
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I totally forgot about the horn antenna, I was looking at the KP 65 degree sector antenna. Good idea? bad idea? LOL
Sorry, I should have asked. It seems as though most operators that want to split up the e3k 4x4 (or the upcoming 4500c 8x8 AP) are wanting to do so using multiple horns or horn arrays. Unfortunately I don’t have experience using the KP 65deg antenna. I do know however that it is a little tricky getting MU-MIMO working across multiple antennas (as indicated in my write up above). I think if your goal is for optimal MU-MIMO performance that works out of the box without any tweaking, I’d stick to Cambium’s OEM 4x4 sector antenna. It will provide around the same coverage area as a 65deg sector and the same gain for slightly less money… and if you have any BSA’s left over from your e2k deployments, you can use those with the e3k OEM antenna, as there are mounts for it at the bottom of the panel.
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Once again your insight has been very helpful and valuable. Thank you Eric!!!
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The problem with the RFE 4x4 dual horn and Mu-MiMo is that the horns cover the exact same zone with no separation. This means in theory that all SMs are Mu-MiMo companions but in reality they do not trigger until the AP is fairly loaded and busy. By offsetting the two horns by 15 to 20 degrees you break this behavior as some SMs (which are 2x2) have a better signal on one half vs the other. This gives better metrics for Mu-MiMo coordination and thus more Mu-MiMo traffic.
Personally I do like the new mount for back to back operation. This makes it easy to get things aligned 180deg and makes mounting much easier with a small foot print; but yes these are much heavier than a panel but with a much better RF edge roll off and no back lobes or problems with rear null requirements as the antennas are mounted side by side in the null, which gives a much improved signal quality that leads to higher sustained modulation rates.
Now if the upcoming 4500C 8x8 can do four way split sector then we would have a mid density tower AP that would be an absolute winner!