The first thread about AM antennas fizzled out so I'm starting another one. I won't bore anyone with details of the AM radio I just designed and built. I'm working on the antenna. I have a tuner taken from an old radio having a variable 22pF to 470pF capacitance. For the AM broadcast band I calculated an optimum inductance of 300uH. I wound a loop stick to this value and experimentally discovered the math to be right. To get the whole HF range I will tap this inductor at various points. But here's my question: Once I put this capacitor and the loop stick in a metal box and that box is grounded don't I need an external wire to attach to the loop stick so that radio waves can accumulate on a conductor that isn't grounded or shielded? I mean couldn't I run the hot end of the loop stick winding out to the roof via coax and there install a metal rod or a long wire for an antenna? It seems to me the old radios had a loop stick plus a point of attachment for a long wire -- just a slotted screw usually. The car antenna comes to mind due to the fact the radio is shielded. Just a hollow metal mast to collect radio waves and feed the tuner. I'm wondering if the original radio designers didn't just discover by accident that the loop stick they had merely planned as an inductor was enough to be an antenna in and of itself? But the original plan was to attach an external antenna -- just some metal -- to the loop stick.