Answer:
It will receive whatever its internal circuitry can pick up with its inductance and capacitance.
In AM receivers in the last 60 years a coil with a ferrite core called a “loopstick” was often used to pick up the B (magnetic) field of the radio signal. In portable radios this can always be spotted as a the large, usually rectangular, black core having windings around it. It qualifies as “part of the radio circuit” and it substitutes for any externally-connected input.
FM receivers work at frequencies higher than the ferrite can handle and usually have a “whip antenna” (a telescoping metal tube, sometimes pivoted) that will pick up the E (electric) field of the radio signal. Even when it is retracted it will still pick up some signal.
