Hi Neil, Then only published info that I'm aware of is the ELF antenna used by the USA to transmit ELF signals on 76 Hz to submarines. This was 'Project Sanguine'. It used about 15 miles of power cable
suspended on 30 foot poles above ground and was earthed at each
end. A TX of around 5 Megawatts, about half way along this cable supplied the 76 Hz at a few hundred Amps. The radiated power was around 3 Watts, and was just sufficient to travel the globe. Project Sanguine
was abandoned some years ago, as it fell obsolete as new sophisticated comms replaced it, such as satellites etc.. It was very expensive, only one way comms, and the 15 mile of cable was constantly being attacked by vandals and metal thieves. Russia still
uses a similar system on 82 Hz (Zevs), and they shoot to kill anyone tampering with their cable!!!
There is an excellent Wikipedia page on Project Sanguine. Basically, it was a very inefficient monster narrow loop.
Otherwise, conventional Marconi vertical masts tuned against ground are used for VLF TX'ing the vertically polarised signals, at any
VLF frequency up to the LW broadcasting band.
From my experience, long low metal structures of any kind do not make good VLF / ELF TX antennas, and for that reason are never employed.
Also, they do not generate a vertically polarised signal, which is very necessary for VLF and ELF propagation.
The historic 'Beverage' type of horizontal wire antenna is long, but only suitable for reception (very inefficient as a TX antenna).
Vertical
balloon suspended wires do work, but you must observe the maximum height restrictions allowed in any particular location.
I hope this is useful.
Kind regards, David
This sounds interesting. Can you point at any published results to explain what technique was used, what power was used to obtain those results, and how the signal was launched? I imagine lots of people are considering the use of long lengths of metal
infrastructure (on private land, with the express permission of the landowner), so if there is a solution which is demonstrably better, it would save a lot of unnecessary trouble for experimenters.
Do you have any numbers comparing the technique used in these experiments against those obtained from using long lengths of armco or metal fencing or huge bridges, (putting aside any arguments about the rights and wrongs). It would be good to see a documented
comparison to show by what margin the experimental technique used is superior to using low steel structures with a large horizontal extent.
Neil
On 10/01/2019 18:37, David Hine wrote:
... TX connexions to motorway
guard rails, railway infrastructure, electric / gas supply utilities and fences etc. are totally unnecessary for the transmitting of ELF
signals.
These DO NOT make good VLF / ELF TX antennas ..
