"KaitoWRX911" wrote in message
...
Why does FM and SW use whip antennas, while AM uses directional
internal ferrite-bar antennas? Couldn't the internal antenna be used
for SW and FM, or vise-versa? Thanks... excuse my ignorance...


Loop antennas are more efficient at lower frequencies, along with being more
directional, and less prone to noise pickup.

Many cheap shortwave radios used internal ferrite antennas (separate coils
on the same bar as the AM/MW antenna) for the main antenna tuned circuits on
the SW bands. This did allow some reception without using the whip.

For VHF/FM, the whip is more efficient because it can approach a 1/4
wavelength of the received signal.