A Mechanically Based Antenna. This is a new DARPA program to develop ULF (0.3-3 kHz) and VLF (3-30 kHz) antenna systems for underwater and underground radio communications (click image below to go to web page). Not exactly a "Newsworthy article about Amateur Radio", and we don't have a ULF or VLF allocation anyway, but I thought the article would be of technical interest to some hams. DARPA image usage policy: http://www.darpa.mil/policy/usage-policy
Ah yes...DARPA...the folks that invented the disparagement : 'fruits and nuts'. Funky way to scare off innovation, don't you think? ;-)
Sorry to spoil your fun Ron, but I am already writing up the patent;-) Ain't no fruit; ain't no nut :-> BTW the wavelengths are of order 300,000 meters...300 KM.
oh yes we do!! for ULF, we can do anything we want 9kHz and below! put megawatts in to the ground, make those earthworms suffer! seriously though, lots of great stuff to listen to in VLF; lots of natural science going on there. very curious things... enjoy
Very coincidental! Last week, I was reading a 1961 Popular Science article: https://books.google.com/books?id=V...&q=popular science earth-radio system&f=false
We all know where this is heading--- TESLA. See review and WARDENCLYFFE description begins p. 51: http://radioclubofamerica.org/wp-co...RCA_2016_Proceedings_Spring_public_lowres.pdf
In this regime, the propagation trumps production. Their mechanical exciters will have ERPs of micro to milliwatts....
To do with VLF: Just for interests sake, JJY in Japan, among others, TXs a time signal at 40kHz from their Fukushima Transmitter and 60kHz from their Kyushu Transmitter, that my wrist watch, a Citizen Skyhawk Gen III picks up, all the way down here in Melbourne, Australia. The receiver in the watch uses the signal to sync the watch's time to the atomic clock's time at JJY. I am truly amazed that a watch, that fits on your wrist, can RX a signal from 8000 kilometres away. Can you imagine the size of the antenna in my watch?? Cheers ... Pete
My /Portable and /Pedestrian Mobile Cave Radio equipment uses 185 kHz SSB and CW with loop antennas and transceivers of my own design. (in the LOWFER BAND) The loop has 10 turns of #18 wire and a high voltage capacitor (with 1 loop turn for coupling 50 ohms to transceiver). The bandwidth of the loop is about 2 kHz. I've talked 1 kilometer through limestone and marble rock with these units. To communicate from the surface transceiver to pedestrian units at more depth down in the cave, a simple (coil-loaded) wire dipole about 200ft long is placed on the ground surface. Also it provides RDF for cave survey. See photo: Cave Radio 185 kHz SSB / CW / Audio Beacon transceiver:
Careful Bonnie, DARPA may try to bestow its favorite moniker on you....as they did to me. Some abuse aint worth the money. Funny how the true innovations easily outlive the tenure of the program managers....of course they then try to recruit you to be a PM. Messed up culture. 73 Chip W1YW
I am a scuba diver and underwater radio comm systems have been around for at least 10 years (probably much longer). These systems are available to the consumer and are not restricted to military, law enforcement or dive teams. The ones I have used operate somewhere around 30khz SSB and are good for about 1/4 to 1/2 mile. I recently met a diver who was active on a local team who told me they have the underwater text devices as well as voice comms. He commented he really didn't use the text device that much because (1) where they normally work the visibility is only a few feet and (2) its difficult and cumbersome to compose a message wearing gloves and dealing with other matters such as current, debris, trees, etc that encountered under water.
Yeh, I have one dissected here on my table. It would be great to have a Made in USA product.... 73 Chip W1YW
The title is misleading: the program to be funded is for a **transmitter**, not an **antenna**. The idea is to come up with a mechanical TRANSMITTER system that matches free space well, thereby cutting down on the ohmic loss of components otherwise needed to cut the reactance of the antenna. The radiation resistance remains very low, but the ohmic loss of the 'tuner' no longer dominates. That's the idea, anyway. This is NOT an antenna. Its a mechanical transmitter.
