Their transmissions would more than likely be omni-directional. It's the most likely configuration of a portable HF or VHF radio setup or satellite phone.
Even if they had sent these transmissions using a directional antenna, at least two receiving stations would be needed to properly determine the location the transmission came from (Which I'm sure we've had setup and listening for sometime).
You could determine direction with one receiver and a specialized type of antenna but you'd have to be close and get very lucky.