LW- MW Huge Receiving Loop Antennas for Broadcasting
and Direction Finding
old radio textbooks you can find description of old magnetic receiving
loop antennas. As a rule, old magnetic receiving loop antennas
had a triangle or square shape, a side of the triangle or square
had length in 10-20 meters. The huge square was put on to a corner.
The distance from the ground up to lower wires of the magnetic
receiving loop usually was not less than 4 meters.
Fig. 1A shows a triangular receiving loop antenna consisting
of two perpendicular loops, used for direction finding at airports
, Fig. 1B shows a square receiving loop antenna
used on Broadcasting Radio Centers of the USSR at the end of 30s
of the 20 Century .
Usually the receiving magnetic loop contained from one up to eight
Fig. 2 shows a typical connection of the above mention huge
magnetic receiving loop antennas designed for working on one fixing
frequency to the receiver. To a resonance the loop A1 is tuned
by lengthening coil L1 (sometimes two lengthening coils switched
symmetrically to both side of the loop were used) and variable
air- dielectric capacitor C1. T1 did connection with antenna feedline.
L1, C1 and T1, as a rule, are placed directly near the antenna
keeping minimum length for wires from the antenna to the parts.
Certainly, there were others circuits for connection magnetic
loops to a receiver, but the circuits were insignificantly distinguished
from Fig. 2.
Small- Sized Magnetic Loop of a Local Broadcasting
loop antennas were used for cities Broadcasting Radio Centers,
for local Broadcasting Radio Centers a small- sized loops were