Question About AM Loops
- I'm trying to understand this loop thing conceptually. Given the two
different configurations, why does a small loop or coil with a ferrite
rod work well inside a radio, whereas a long Beverage type antenna
also work just as well? Is it the length of the total wire? Does the
3 dimensional configuration of the loop/coil catch the wave better,
especially since reception is directional? If you build a coil, like
a hula hoop type antenna with a few turns, no ferrite rod is
required. I'm thinking the magenetic component of the radio wave
induces a modulated voltage in the wire, but not sure what the key is
here. The better I understand it, the more ideas I'll have to try.
> I'm trying to understand this loop thing conceptually. Given theLoops are magnetic field antennas instead of electrostatic field
antennas. The larger the area of the loop, the more lines of magnetic
flux it intercepts. That is why a ferrite bar antenna works - the
ferrite concentrates magnetic flux in what would ordinarily be a loop
that is too small to be effective.
Having never built a beverage antenna for these frequencies due to lack
of space, I can't really speak to why it works. However, I suspect it
is because - even with low gain - it is large enough to intercept the
magnetic flux. It is therefore a great broadband solution, if you have
the land to construct it.
The smaller tuned loops we discuss here take advantage of parallel
resonant bandpass filter characterisitics to have gain.