IIRC, in this case the origin of the "antenna" command is a spreadsheet from Samsung that lists it among the discrete commands for the newer models. Most of the commands listed work but AFAIK, no one has found the "Antenna" command to work.

So, to reinforce John Fine's point (and mine earlier), it is NOT a problem of tweaking the IR command, Samsung apparently forgot to set their firmware in the TV sets to accept the Antenna command.