IWR1443: question about transmit simultaneously from 3 Tx

Hi,

I have a question about the number of simultaneously transmit antennas in IWR1443.

The IWR1443 data sheet states that simultaneous transmission is possible with two Tx.

However, I am confused because the OOB demo is capable of transmitting 3 Tx and Cfg notifying 3 antennas.

I compare the IWR1443 with the IWR1642 and I understand that the added third antenna is an antenna with resolution in the elevation direction.

Using the OOB demo as an example, if 3 Tx is set, are you transmitting at the same time, or you are using one of the two azimuth antennas and one elevation antenna at the same time?

If it is not transmitting simultaneously on 3 Txs, I also want to know how to realize MIMO for azimuth and elevation direction.

(I understand that implement MIMO using 3 antennas, two in azimuth and one in elevation.)

Best Regards,

Takuma