I propose a simple radio microphone circuit with a range of up to 30 meters. The signal can be received on the radio (cell phone, player or on a regular, etc.) If everything is assembled correctly works without settings.
The coil contains 7 turns, I used 0.45mm, after you solder the coil, it is advisable to fill it with glue so that the turns do not move.
I think the length of the antenna you pick up the longer, the farther.
For food, you can use the crown.
The very idea of this microphone is that when it is received, the receiver does not hiss.