Gain using single antenna on Aironet 4x4 MIMO device

[KevinHowJones]

I'd like to configure a CAP-3602E in order to use with a single element grid antenna, as I have several of them laying around.

I assume that when I'm in full 4x4 MIMO mode (all antenna ports enabled), if I have Tx power set at 23dBm, each antenna port is receiving 17dBm (1/4 power). When I configure to use "a" port, (thus turning off b, c and d) I am wondering what happens in regard to the Tx power. Is all 23dBm then available at port "a"? Or will it still only be 17dBm, thus effectively making the radio operate at 1/4 power?

[Flavio Miranda]

Hi @KevinHowJones 

 I understand this a bit different then you. I dont think the TX power is divided by antennas but by channel. On the 3600 Data sheet you can read this:

"Note: The maximum power setting will vary by channel and according to individual country regulations. Refer to the product documentation for specific details."

5 GHz

●  802.11a

◦   23 dBm: 4 antennas

●  802.11n (HT20)

◦   23 dBm: 4 antennas

●  802.11n (HT40)

◦   23 dBm: 4 antennas

We do have the 17dBm option but it would be for any antenna. 

5 GHz

●  23 dBm (200 mW)

●  20 dBm (100 mW)

●  17 dBm (50 mW)

●  14 dBm (25 mW)

●  11 dBm (12.5 mW)

●  8 dBm (6.25 mW)

●  5 dBm (3.13 mW)

●  2 dBm (1.56 mW)

[KevinHowJones]

Hmm, I only have a very limited understanding of how MIMO works but the way I understand it is that the 4 antenna array is used to provide a beam-forming pattern by heuristically adjusting the phase of the signal at each antenna based on where it makes the strongest connection(s).  IIUC, the total energy in the beam from a phased-array system (which I believe is what this constitutes) is a result of the sum of the power to each antenna.

What I am trying to ascertain here is, will this radio set at 23dBm, single antenna port option selected, have the same power at the antenna port as a single antenna (non-MIMO) device set at 23dBm?

[Flavio Miranda]

Thats what I understand.

[KevinHowJones]

"Thats what I understand"

To the first paragraph or the second or both?