Small Antennas Could be a Big Deal for the Air Force

Ultra-compact antenna that is smaller than a flea shown in relation to a quarter and small surface acoustic wave (SAW) device

Ultra-compact antenna that is smaller than a flea shown in relation to a quarter and small surface acoustic wave (SAW) device

December 4, 2017 | Source: Armed with Scinece, science.dodlive.mil, 17 October 2017, Holly Jordan

Researchers at the Air Force Research Laboratory’s Materials and Manufacturing Directorate, in partnership with Northeastern University, recently developed an ultra-compact antenna that uses a whole different approach in transmitting and receiving signals. This breakthrough could be a big step in the miniaturization of many military and commercial communication systems.

Typical antennas rely on size to function effectively in the electromagnetic spectrum. If the antenna is not long enough to resonate at the proper frequency, the antenna will not be able to transmit or receive the desired electromagnetic waves efficiently

These ultra-compact antennas represent a whole different approach to this type of technology. Instead of using an electrically-conductive material to sense the electric field of microwaves, these antennas use special insulating materials, called “multiferroic composites.” These materials are composed of magnetostrictive materials, which convert magnetism to strain, and piezoelectric materials, which convert strain to voltage converting material. Using the multiferroic composites allows the ultra-compact antennas to function by sensing the magnetic field of microwaves.

“We miniaturized the antennas by borrowing a trick from acoustic filters in cellphones, which convert microwave voltages to strain waves. Strain waves travel much slower than the speed of light, so by doing this, we are able to shrink the wavelengths while keeping the frequency the same. This allowed us to make the antennas much smaller,” said AFRL materials scientist Dr. Michael McConney. He added that by coating conventional bulk acoustic wave filters with a magnetic material, these slower strain waves can be converted into radiation, which enabled them to break the inefficient scaling laws associated with shrinking typical antennas to very small sizes.

This new approach allowed the team to reduce the size of an antenna by over 90 percent. This development could result in smaller devices including wearable antennas, bio-implantable and bio-injectable antennas, smart phones, and wireless communication systems, to name a few.