SWRA689 February 2022 AWR6843 , AWR6843AOP , IWR6843 , IWR6843AOP
Number of Tx Antenna is first enabled by parameter txChannelEn, which is the 2nd parameter of channelCfg. The value is configured as a bitmask, thus the value 5 corresponds to enabling of Tx 1 and Tx3.
Furthermore, the antennae are configured with the parameter Tx Antenna Enable Mask, which is the 8th parameter of the chirpCfg parameter set.