To find the second SIM card, you will have to go to the Industrial District located in central Arkham, to the North of the bridge. After you approach the destination, I recommend that you take a vantage point. That is because this area is being patrolled by three enemies equipped with firearms. I recommend that you take the enemies by surprise, because Batman could quickly die in direct fights. First of all, target the single enemy shown in the screenshot, and attack him from above. I would be good if you already had the Dive Bomb attack unlocked because the enemy will then die on the spot. If you still have not unlocked this one, make sure that you finish off the gangster.
Right after the successful attack, use the hook to leave this place quickly. What is even more, if you have been spotted, drop the smoke pellet, which will allow you to blind the remaining enemies temporarily. There are two more enemies to eliminate. Wait for them to scatter and attack one of them from above. Run away again and end up by eliminating the last one of the bandits.
The radio that you are looking for is in the spot shown in the above screenshot. Wait for Batman to collect the SIM Card and start the Cryptographic Sequencer. Decipher Penguin's transmission, which will allow you to determine that he is staying aboard a ship moored near the Amusement Mile.