Aux Cord as FM Antenna

179

01:21:54

So, I noticed my phone's FM app worked when I plugged in my headphones, yet when they weren't plugged in, my phone couldn't receive a single FM station. So I came to a conclusion: My phone must be using a technology similar to some MP3 players where the cord to the headphones/speakers was used as an FM antenna. So I thought: "Ok, but how? I still would have to filter lower frequencies." Then I remembered, " HIGH PASS FILTER" And thats how I came to the conclusion to make this circuit.

10KHz is a standard audio from the Aux alone

100MHz is an FM station

published 7 years ago

hurz

7 years ago

As antenna the ground shield is used. Its importante as you said to avoid AF into tuner input. But tuner do have all filtering as bandpass SAW filter already in, AF is easily rejected. More importante is to avoid short circuit RF to ground by use of a choke coil e.g. lets say 10uH which let pass AF but block RF

hurz

7 years ago

http://everycircuit.com/circuit/5373466592411648

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