ELF

These are my presentation notes from the Maxwell City workshop in June this year.

Extremely low frequency transmitters were developed for communication with deeply submerged submarines at depths of more than 200 metres and under polar ice-caps. Submarines below this depth are undetectable by radar and other non-acoustic systems.

Conventional radio communications on the VLF range have wavelengths that only penetrate the water to between 10-40 metres, depending on the salinity (or conductivity) of the water. This is barely periscope depth for a modern sub eg a radio signal propagated at 20Khz (which has a wavelength of approx 30 km) will only penetrate water by a matter of metres. To receive communications at this frequency, subs have to surface and de-crease operational speed.

ELF makes use of the principal that the ‘absorption’ (please note the unscientific language – ‘attenuation by’ is the correct phrasing) of radio waves in the sea water, increases with the frequency of the wave, therefore the lower the frequency, the deeper the useable signal will travel.

As stated before, a VLF of 20Khz will only travel into water for a matter of metres; the ELF system uses frequencies of 76-82 Hz, the wavelengths of which are over 3500km – a quarter of the earths diameter; because of the slowness of the frequency, only a few character per hour can be communicated.

As antennae lengths needed to propagate signals has to be half the length of the cycle of the wave, this would mean that the antennae needed to produce a 76Khz signal would be 1800km long.

Use is therefore made of a combination of vast amounts of overhead cable and geographical locations that contain base-rock formations such as igneous granite, which provide a low-conductivity site for the antennae. Bore-holes are drilled into the rock into which are inserted thick copper wire. The geological formations channel ELF currents deep into the ground, increasing the size of the antennae; in effect making the Earth itself an antennae.

The ELF travels round the world through the atmospheric layer between the Earths surface and the zone of charged particles, the ionosphere. As the electromagnetic waves pass over the oceans surface, some of their energy passes into the water. This energy reaches subs worldwide, however, because of the large amounts of power, large-scale transmitters and antennae needed to propagate ELF signals, it is a one-way communications system only.

Three sites in the world have ELF transmitters. Two of them are in North America – Chequamegan National Forest in Wisconsin and Copper County in Michigan. These are dual antennae transmitting systems. The Wisconsin antennae consists of two above ground lines each 22km long with a site area of two acres. The Michigan system uses three above ground lines, two of 22km and one of 44km. The transmitter site area is six acres. The two sites are connected by a 264km underground cable which has an operating frequency of 76Khz. The power required was taken from the national grid, with a back up generating system capable of providing three million Kilo Watts of power to the site (that means nothing to me oh Vienna, bad 1980’s number)

Transmission from these sites started in 1989, with a synchronised ELF transmission to the U.S Submarine fleet 24 hrs a day seven days a week. Final transmissions ceased in 2003 (?) after much public speculation over the environmental impact, an example of which is that freshly planted trees reportedly grew quicker in these areas.

One ELF transmitter is still in operation. This is the ZEVS transmitter (just up the road from Atelier Nord) in the Kola peninsula near Murmansk in Russia. This operates at 82Khz and uses two underground parallel antennas of 60km. again the antennae is situated in granite bed-rock.

This site was only detected in 1990 after radio transmissions at 82Khz were received at various locations throughout the world including Arrival Heights in Antarctica. The system is still in use but is now also used for geophysical surveys and seismic investigations.

I have also read reports that the US are using the HAARP site in the Arctic to test out ELF as well as VHF propagation.

Please note that all references are plagiarised from various internet sites, and all kilometric measurements are approximate as I had to convert them arithmetically (manually) from miles.