On Sat, 8 Apr 2017, Gareth's Downstairs Computer wrote:

When you consider the reduction in the size of antennae when going
from dipoles et al to magnetic loops, I wonder why those
on wildlife safaris who have attached beacons to animals
use full size yagi-udas to track the animals?

Surely the same reduction in size should be possible
with mag loops for VHF?


Because the frequencies are high enough that a full antenna can be used.

The bigger/better the antenna, the more gain it has, useful for finding
those low power transmitters, and the more diectionality the antenna has,
which is really useful for tracking small animals.

A lot of direction finding in general has been at "low" frequencies like
the AM broadcast band (all those beacons, and of course broadcast stations
were once used for homing), and those used loopsticks. But low
frequencies don't work so well when you want a small transmitter and
antenna.

Loop antennas have been used for direction finding, but that seems well in
the past. The move has been to bigger antennas for the gain and
directionality.

Michael