My piece last week on FMX, the discarded radio technology that faded from view, drew a comment from reader Conrad Kramer, who was drawn to one of the side elements, where I discussed efforts by the broadcasting industry to get FM radio functionality enabled in smartphones.
He pointed out something interesting that I thought was worthy of sharing with the rest of you guys:
The WiFi + Bluetooth chip that Apple uses in every iPhone does indeed have an FM transceiver built in, but it requires an antenna in order to function, one larger than any of the internal antennas. The only way people have gotten this to work (on Android phones) is by plugging in analog headphones and having the headphone wire double as an antenna.
This, as it turns out, is not something unique to smartphones. It’s actually a design feature of pretty much every portable audio device that includes an FM (but not AM) radio. It’s an approach that dates to the days of the Walkman.
For example, the iPod Nano, the only iPhone variant that natively supports FM radio functionality, requires headphones to be plugged in for this purpose, per its manual. And Sony’s Walkman manuals recommend that, if your radio signal quality is low, you stretch out your headphone cable.
All of this is because, due to the design of FM radio technology, you need an antenna of at least a meter to pick up a decent signal. (Per Explain That Stuff, 1.5 meters is the ideal length for a good antenna.)
Clearly, there’s no room for an antenna to protrude out of the device, so the wire already connecting out of the device has to do the job. In other words, headphones have a somewhat clever hidden design feature that most people don’t think about.
And it’s one thing that Bluetooth won’t be able to replace.
(Photo by Jon Pinder/Flickr)