Jps,
The ultimate aerial for an AM Radio set is a long wire Inverted-L type arrangement.
When AM radio was all they had, radios used one wire to the aerial itself and another to a Ground stake nearby.
However, it must be said that any loop aerial used for AM radio reception will be inherently directive (ie: they must be pointing side-on to the station to be recieved).
For extending wiring to a loop aerial in this fashion, you neeed to use 300 ohm ribbon (Twin-lead) or you will end up with a mis-match between the aerial and the connecting wire and this will result in signal degradation.
Hope this helps. [Linked Image]