DARPA seeks to expand wireless underground
Fri 23 Dec 2016
DARPA is seeking input on its A Mechanically Based Antenna (AMEBA) project, which will use low-frequency electromagnetic waves to expand wireless communications underground, undersea, and to other areas previously inaccessible.
They have scheduled a proposer’s day for early January, when they will detail the requirements and answer questions from parties interested in contributing to the project.
The AMEBA project is designed to develop a new type of transmitter that exploits unique capabilities of electromagnetic frequencies at the very end of the scale – ultra low frequency (ULF) and very low frequency (VLF) waves. The transmitter should be small enough to be carried by a person and functional whether they are above ground, below ground, or underwater.
ULF waves range between hundreds of hertz and 3 kilohertz, and can penetrate water, soil, rock, metal and building materials. VLF waves range from 3 to 30 kilohertz and can use the atmospheric corridor between the Earth’s surface and the ionosphere as a radio waveguide, capable of continuing a radio signal halfway around the world. Combining the characteristics of ULF and VLF means that, conceivably, a person underground or underwater could generate a radio signal that could be projected to a receiver hundreds of miles away.
Previous experiments in putting the atmospheric corridor to use as a radio guideline for VLF frequencies have been huge and costly. For example, the VLF antenna in Cutler, Maine built in 1960 requires over 2 acres of land to house 26 radio towers, some up to 1,000 feet tall.
The challenge for the DARPA researchers is to condense the volume of the transmitter and power requirements, using innovations in chemistry, materials, design and engineering to make a smaller transmitter than any that has yet been achieved.
The key to meeting that challenge is to look at creating a radio transmission in an entirely new way. Traditional transmitters rely on oscillating electrical currents that initiate radio signals. Transmitters for the AMEBA program would instead use mechanically moving materials with strong electromagnetic fields to generate a signal.
Troy Olsson, program manager of the Microsystems Technology Office at DARPA, said, “Mobile low-frequency communication has been such a hard technological problem, especially for long-distance linkages, that we have seen little progress in many years.”
“With AMEBA, we expect to change that. And if we do catalyze the innovations we have in mind, we should be able to give our warfighters extremely valuable mission-expanding channels of communications that no one has had before.”