The result is an antenna that operates at very low frequencies, around 35–36 kHz, while remaining far more compact than the conventional electrical antennas that work at those same frequencies.
They are using a super low frequency.
show comments
DoctorOetker
this transduces between magnetic <-> acoustic <-> electric domains, via acoustic pressure.
does this result in some acoustic side channel emissions? can an adversary track subs by correlating acoustic with EM noise if this were employed on second strike submarines?
conceptually its like a 3 port device: a magnetic port, an electric port and an acoustic port.
One would be especially interested in the scattering parameters S_mag-acou , S_acou-mag , S_elec-acou, S_acou-elec at the used frequencies, for passive detection, and for wider frequency range for active detection...
show comments
raffael_de
my first association here would be steering of torpedoes. the US Navy must have been on this for decades and very deep pockets.
show comments
peter_d_sherman
"At 36 kHz, the wavelength shrinks from roughly 8,327 m (27,320 ft) in air to just 170 m (558 ft) in freshwater..."
Yes, waves apparently compress or expand depending on the medium they are in...
I'm curious as to what the extremes of potential medium might be... on one end, we might have the densest of heavy metals and on the other, we might have the vacuum of outer space...
Also, what role does/would temperature play?
If a heavy metal was frozen and its temperature brought as close to absolute zero as possible, then would that shrink or expand any propagated waves through it, if even by the smallest amount?
Also, if so, might there be a definable relationship between that phenomena, if it exists, and superconductivity?
Anyway, great article, and it's interesting to learn about Magnetoelectric Antennas!
(I had never heard about them before!)
show comments
cyanydeez
youd think optic fiber like Ukraine is diing would be viable to some extent.
show comments
rpaddock
In World-War-One J.H.Rogers invented and patented an antenna that worked well underground or underwater. It was used to communicate with Subs at the time.
According to the late, and somewhat controversial, T.E.Bearden the Rogers system has been rediscovered and then "lost" at least five times since WW1.
"James H. ROGERS
Underground & Underwater Radio
( Static-free Reception & Transmission Underwater & Underground )"
While not indented for water use the Sutton & Spaniol et.al.'s "Black Hole" Antenna is always of interest when it comes to VLF/ELF. This work was done for NASA. Dr Sutton described it to me this way:
"Re: ACTIVE ANTENNA
From: John and Helen
Date: 10/02/05 10:54 pm
Hi Bob,
The synchronous detectors were used in temperature monitors and temperature controllers designed to control temperatures on spacecraft at 60 milliKelvin +/- a few ucroKelvin. The preamplifier had to have a gain of 10E5 after which the demodulated signal had to be converted by a 16 bit ADC, with +/- 1LSB allowable error.... so of course, you can see that we were working with extremely small signals buried in the noise, and we had to go all out in an effort to beat down the noise. That's why we had to use a new improved synchronous demodulator. This project was as close to being impossible as you can get! I still have trouble believing that we actually made it work.
The active ("Black Hole") antenna was developed in another project, where we didn't want to transport a two meter long antenna that weighed 200 pounds.....so we miniaturized the hardware while simultaneously expanding the antenna field cross section. We wanted to receive the entire ELF-VLF bands all at once, so we had to have an extremely broadband antenna....like four decades of bandwidth or more. You wouldn't believe the arguments I had with the reviewer at Physics Essays. He just couldn't believe that one could do what we did....and if it was indeed true, then why hadn't someone done it years ago?.., "and what makes you so smart", .so, of course, "this must be nonsense, etc....." Progress in physics is so bloody difficult because most physicists think that everything worthwhile has already been discovered....so they expect nothing new. This is negative feedback which, of course, makes the system stable, I suppose.
The one text book that includes diagrams of the antenna-external field interaction is listed as one of the references in the Physics Essays paper. Sorry, I can't remember the name of the author or the title.
I was wondering how this could make sense until:
The result is an antenna that operates at very low frequencies, around 35–36 kHz, while remaining far more compact than the conventional electrical antennas that work at those same frequencies.
They are using a super low frequency.
this transduces between magnetic <-> acoustic <-> electric domains, via acoustic pressure.
does this result in some acoustic side channel emissions? can an adversary track subs by correlating acoustic with EM noise if this were employed on second strike submarines?
conceptually its like a 3 port device: a magnetic port, an electric port and an acoustic port.
One would be especially interested in the scattering parameters S_mag-acou , S_acou-mag , S_elec-acou, S_acou-elec at the used frequencies, for passive detection, and for wider frequency range for active detection...
my first association here would be steering of torpedoes. the US Navy must have been on this for decades and very deep pockets.
"At 36 kHz, the wavelength shrinks from roughly 8,327 m (27,320 ft) in air to just 170 m (558 ft) in freshwater..."
Yes, waves apparently compress or expand depending on the medium they are in...
I'm curious as to what the extremes of potential medium might be... on one end, we might have the densest of heavy metals and on the other, we might have the vacuum of outer space...
Also, what role does/would temperature play?
If a heavy metal was frozen and its temperature brought as close to absolute zero as possible, then would that shrink or expand any propagated waves through it, if even by the smallest amount?
Also, if so, might there be a definable relationship between that phenomena, if it exists, and superconductivity?
Anyway, great article, and it's interesting to learn about Magnetoelectric Antennas!
(I had never heard about them before!)
youd think optic fiber like Ukraine is diing would be viable to some extent.
In World-War-One J.H.Rogers invented and patented an antenna that worked well underground or underwater. It was used to communicate with Subs at the time.
According to the late, and somewhat controversial, T.E.Bearden the Rogers system has been rediscovered and then "lost" at least five times since WW1.
"James H. ROGERS Underground & Underwater Radio ( Static-free Reception & Transmission Underwater & Underground )"
https://www.rexresearch.com/rogers/1rogers.htm
There is also
Wallace MINTO Hydronic Radiation Transmitter
Radio-Electronics (May, 1967), p. 37-38.
“Build a Hydronic-Radiation Transmitter”
by Jack Althouse
“Scientists in Florida have discovered a new form of electromagnetic radiation which propagates under water as well as radio does in air”.
https://www.rexresearch.com/hydronics/hydronics.htm
While not indented for water use the Sutton & Spaniol et.al.'s "Black Hole" Antenna is always of interest when it comes to VLF/ELF. This work was done for NASA. Dr Sutton described it to me this way:
"Re: ACTIVE ANTENNA From: John and Helen Date: 10/02/05 10:54 pm
Hi Bob,
The synchronous detectors were used in temperature monitors and temperature controllers designed to control temperatures on spacecraft at 60 milliKelvin +/- a few ucroKelvin. The preamplifier had to have a gain of 10E5 after which the demodulated signal had to be converted by a 16 bit ADC, with +/- 1LSB allowable error.... so of course, you can see that we were working with extremely small signals buried in the noise, and we had to go all out in an effort to beat down the noise. That's why we had to use a new improved synchronous demodulator. This project was as close to being impossible as you can get! I still have trouble believing that we actually made it work.
The active ("Black Hole") antenna was developed in another project, where we didn't want to transport a two meter long antenna that weighed 200 pounds.....so we miniaturized the hardware while simultaneously expanding the antenna field cross section. We wanted to receive the entire ELF-VLF bands all at once, so we had to have an extremely broadband antenna....like four decades of bandwidth or more. You wouldn't believe the arguments I had with the reviewer at Physics Essays. He just couldn't believe that one could do what we did....and if it was indeed true, then why hadn't someone done it years ago?.., "and what makes you so smart", .so, of course, "this must be nonsense, etc....." Progress in physics is so bloody difficult because most physicists think that everything worthwhile has already been discovered....so they expect nothing new. This is negative feedback which, of course, makes the system stable, I suppose.
The one text book that includes diagrams of the antenna-external field interaction is listed as one of the references in the Physics Essays paper. Sorry, I can't remember the name of the author or the title.
John Sutton, Ph.D."
https://web.archive.org/web/20120722112702/http://www.unusua...