4 ms·
How big an antenna would a cellphone with an AM receiver need?
by pkaye 7y ago
How big an antenna would a cellphone with an AM receiver need?
- 0b0001 7y agoIf I remember correctly, cellphones with radio receivers tell you to plug in headphones whenever you're tuning in. My guess is the headphones cables act as the antenna. [Edit: TIL AM stations seem to transmit at frequencies way smaller than FM]
- AWildC182 7y agoAM is around 1Mhz so that's a 300 meter wavelength. For a half wave dipole (basic high efficiency antenna) that's 150 meters of wire. A vertical antenna (like on your car) using a ground plane as the other end of the dipole would be 1/4 wave so 75 meters. All this said, AM @ 1Mhz propagates very efficiently regionally and they broadcast at insane power levels so efficiency on your end isn't that big a concern if you're within a couple hundred miles of the transmitter. You can get away with a meter long antenna just fine.
- deleted 7y ago[deleted]