In relation to my other post:http://forum.mikrotik.com/t/3x3-6x6-mimo/47191/1
the question arose; Why does most manufacturers for 2x2 mimo use different polorized antenna’s and not 2 x V or 2 x H?
3x3 or 6x6 MIMO I found are all V-polorized? So, if interference of same polorization would be the issue, how do they solve that with 3 antennas?
Any dis/advantages for either of the solutions? Anybody with any experiances?
For one, dual polarity really seems to help get signal through trees.
More than a few people were comparing dual polarity 802.11n 2.4GHz to 900MHz performance.
I’ve got a few AP’s that are MIMO and V pol only. I don’t have enough feedback or info to say whether they are really benefiting from it or not. My CPEs are all single radio/antenna.
Also, you have to figure that 30dB difference between polarity has to make more of a difference at a distance. With a consumer router and a laptop the noise issue just really isn’t there.
hmm, strange. It is the vapour in the leafs that actually consume the radio wave energy. I do not really see that polarity of the signal would have any influence on that. Or it must be that some part of the signal is also reflected by the leafs. But that could happen to the same extend for both of the polarities. It can only be in certain circumstance one polarity would do better compared to the other. But it could change by the minute.
Also, you have to figure that 30dB difference between polarity has to make more of a difference at a distance. With a consumer router and a laptop the noise issue just really isn’t there.
I work with a fixed P2MP network where all clients have directional antennas.
Thanks for your comments.
I didn’t mean to imply otherwise. The only MIMO I’ve seen that wasn’t dual polarized was short range equipment. I was just stating the differences I’ve observed.
From my experience a -85 in my home or yard is a very stable signal. The same signal 15 miles out is highly dependent on a number of factors. My earlier point being that two short range signals using the same polarity will behave very differently than the same signal strength on long range links. The dual polarity offers more resistance to self interference, as well as interference in general.
I agree with you that dual polarity is the best because it stops self interference. However if you use 1 spatial stream you are doing multipath. Which the same data is sent over both antennas giving you redundant signal. Doing this you dont self interfere unless you are getting some bad reflections that delay a signal. Thus receiving 2 signals at different times.