After paying a rather large amount to keep my car in a car park with a ticket to get out. Should of taken the caterham and driven under barrier

To get in you have to drive up to a barrier and push a button and it gives you a ticket to let you in

To stop you getting a ticket with no car there is some sort of loop in the ground to detect said car.

Is it possible to build a pocket sized device to stick near this loop to pretend to be said car ?