My first idea was that it's a HuffDuff, a high frequency direction finder (HF/DF), used in WW2 to triangulate and pinpoint the position of moving enemy radio transmitters (that is, radio transmitters on German U-boats).

It was featured prominently in Neal Stephenson's Cryptonomicon. Of course Wikipedia shows that those machines looked way more complicated, so the antenna finder in the other comments are more probable.

That's pretty harmless as long as it's only about parking tickets; but did you hear about the German diamond heist where police found DNA but couldn't detain the suspect because they couldn't prove whether it was him or his identical twin? They both got away.
Link:
http://www.spiegel.de/international/germany/0,1518,614245,00.html