The standard of 802.11n offers the connection in MIMO technology. There is a possibility to use 1-4 polarizations in that standard. These days the most popular are 2x2 connections using Horizontal and Vertical polarizations. For more than 2 antennas to separate radio streams there are needed more polarization options. We achieve them by the rotation of antennas achieving X polarity, so simply speaking means +45 and -45 deg polarity (with relation to V or H polarity).
The standard of 802.11n offers the connection in MIMO technology. There is a possibility to use 1-4 polarizations in that standard. These days the most popular are 2x2 connections using Horizontal and Vertical polarizations. For more than 2 antennas to separate radio streams there are needed more polarization options. We achieve them by the rotation of antennas achieving X polarity, so simply speaking means +45 and -45 deg polarity (with relation to V or H polarity).
I. Polarizations
First of all I’d like to explain how to see on the polarizations in X-pol antennas. On the picture below (Pic. 1) there are shown polarizations including X polarity (+/- 45 deg) – left side and how they are seen as the mirror reflection – right side.
Pic. 1 Polarizations in WiBOX SA D4M5-90-17HVX, WiBOX PA D4M5-20HVX and WiBOX PA D4M6-20HVX antennas.
II. MIMO Connections
The point is to understand that in the mirror reflection, so when antennas are situated in front of each other, in X-pol, PORT 3 „becomes” into PORT 4 and PORT 4 „becomes” into PORT 3
1. MIMO 1x1
There are 4 possible connections:
2. MIMO 2x2
There are 6 possible connections:
3. MIMO 3x3
There are 6 possible connections:
4. MIMO 4x4
There are 2 possible connections:
III. More about this solution
These antennas apart from standard given above configurations can work in any other MIMO connections, for example 1x2, 2x3, 4x2 etc. About MIMO read this text 802.11n standard - essentials, advantages and changes .
There can be also another type of combinations as two separate connections 2 x MIMO2x2, the point is to remember that in mirror reflection PORT 3 must be connected with PORT 4 and PORT 4 with PORT 3 of another antenna.
Important thing is to use high quality pigtails for the connections inside WiBOX system, and if possible don’t cross the cables to avoid interferences.