The loop antenna goes back to the early days of radio when
every ounce of signal you could get was needed. Long wire antennas picked up
more signal but they also picked up all the static and other interference, often
resulting in bad reception.
Fig.1: the circuit of the tuned antenna could hardly be simpler: a tapped coil with a variable capacitor across it. That forms a "tuned circuit" and at one particular frequency, which depends on the setting of the tuning capacitor, the tuned circuit becomes resonant.
The loop antenna improved the situation in being both tuneable
and directional, thus maximising the wanted signal and minimising the unwanted
signals and noise.
The end result was a greatly improved signal-to-noise ratio and
the possibility of digging almost unreadable signals out of the noise.
A loop antenna of reasonable size will pick up far more signal
than the more modern ferrite rod antenna which was introduced mainly because it
was smaller and fitted in with receiver miniaturisation.
This new loop antenna, called the Techniloop MS1, supersedes
the model PX1 which was described in the June 1989 issue of SILICON
The new model has contemporary styling plus the addition of
shielding (Faraday shield) to further reduce noise and give a deeper directional
null of interfering signals.