SdKfz 261, 4 Rad, Radio - SdKfz 261, 4 Rad, Radio was a development of the SdKfz 222 armored car.  The obvious difference was the massive radio antenna that surrounded the top of the vehicles.  Long range radios took up a lot of space and required large antennas.  These armored cars operated from the beginning of the war to the end, but were scarce by the middle of the war.