ARLA/CLUSTER: Transmissor e antenas da Estação russa ZEVS para Submarinos.

[João Gonçalves Costa]

[http://www.vlf.it/submarine/subtxf.jpg]
RECEPTION OF SUBMARINE COMMUNICATION SYSTEMS



The Russian ELF transmitter Zevs,consists of two swept-frequency generators of sinusoidal voltage and two parallel horizontal grounded antennas, each about 60 km long. The generators provide 200-300 A currents in the antennas, in the frequency range from 20 Hz to 250 Hz.

But there is one correction to be made; the two parallel 60 km long antennas is not the antenna at all, but the feedline. The actual antenna is the earth itself. By building the antenna at a location with a poor effective conductivity of the ground, and by grounding the ends of the feedline / antenna, the signal is forced deep down into the earth, making the earth itself the effective radiating element.

The actual look of the visible part, the feedline, of this giant antenna, is much like the old telegraph wires hung up on telegraph poles. Down from the last pole at the end of each antenna leg, there is a thick copper wire down to the ground and installed deep in a borehole, making up for the earth connection. (See the open Lab article "Reception of submarine communication systems" by IK1QFK and OH2LX for an principal sketch of an ELF antenna system ).

Calculations performed on data collected back in 1990, also show us that the 82 Hz Zevs ELF transmitter is 10 dB more powerful then the US Navy 76 Hz ELF transmissions from the dual WMT/MTF sites.



Fonte: ZEVS, THE RUSSIAN 82 Hz ELF TRANSMITTER A Extrem Low Frequency transmission-system, using the real longwaves By Trond Jacobsen at ALFLAB, Halden in Norway.
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