What specific kind of signals are you trying to pick up, and what is
it that will prevent you from hearing them? That is, if the signals
are buried in atmospheric noise, a more "sensitive" antenna that also
picks up more noise as well as more signal isn't going to help the
signal-to-noise ratio. For that, you may need to use some additional
knowledge about the signal that you can use to differentiate it from
the noise. At 457kHz, atmospheric noise is very high amplitude, and
it doesn't take much of an antenna plus receiver to get all the signal
that will do you any good.

On the other hand, if the thing that keeps you from hearing the
desired signal is an interfering signal, the null of a loop (or
ferrite rod) antenna can be used to get rid of that signal that comes
from one direction (which lets you listen more easily to the desired
signal, provided your desired signal isn't coming from the same
direction).

Cheers,
Tom


The signal itself is coming from an avalanche transceiver ( a pulse at
457khz every second or so) which has a relatively small antenna and
the signal attenuates quickly , most receivers only have about a 25m
straight line range and I'm trying to improve on that. I thought the
small range was due to the weakness of the signal, I'm a bit clueless
as to how much of the problem would be from radiant noise, although
these posts are starting to give me some insight. Thanks for the help
thus far.

-Chris