Even though it works well, there are practical problems with the current technology.
“Electromagnets are fairly large,” said Page. “They can’t be miniaturized, and they use a lot of power. On a larger platform, that’s not an issue, but the way the Air Force is moving, we expect to have a lot of smaller autonomous platforms, drones, where you can’t use a big bulky filter with an electromagnet and a big power supply.”
Current technology is based on an yttrium iron garnet (YIG) magnetic sphere, which is, according to team member Dr. Piyush Shah, about the size of a hockey puck. “The power unit currently used is about the size of a shoebox,” added Shah. “Our filter is about half the size of a matchbox, everything integrated.”
Instead of a YIG electromagnet, the new design uses a layer of piezoelectric material, a material that becomes electrically charged when subjected to pressure. That layer is coupled with a very thin film of permanently magnetized material. “The result,” said Page, “is a low-power, frequency-agile, small, light-weight, RF-tunable device at a much lower cost. Maybe one percent of the cost of current technology.”
“At its heart,” said Page, “the technology we’re looking at is actually very similar to what’s used in modern cell phones. Cell phones have these types of filter banks, but they’re not tunable. The tunable technology depends on big bulky components. We’re trying to get the tunable capability in a compact device similar to the size of a cell phone.”
“Today’s top-tier smartphones use about 50-70 tiny filters to operate in different frequency bands,” said Shah. "More RF filters occupy too much valuable space on the smartphone circuit board, and therefore we believe our invention could potentially decrease the number of RF filters by replacing them with tunable filters.
“The technology is not restricted for cell phone devices, but other forms of wireless communication systems as well,” added Shah.
“AFRL began work on this technology about five years ago, but specifically the idea of the patented technology evolved in December 2016,” said Shah. “We have shown the fundamental physics of the device and possible functionality of the proposed invention,” said Shah. “Our next goal is to improve the application-relevant performance metrics of our device.”
Page hopes to have a workable prototype in three to six months. “We submitted the patent on the concept in 2017,” he said, “and we’ve been working on it ever since. So, we are actually farther ahead on the project now than we were when we filed the patent’s paperwork.”
The team hopes that their progress in developing the technology will be significantly accelerated as a result of their newly formed partnership with Sandia National Laboratory.
“The prototype will be as good as the type of technology it is replacing,” said Page, “but of course it will have its own advantages. It will be much smaller in size and weight and it will need much less power.”
The Air Force Research Laboratory is the primary scientific research and development center for the Department of the Air Force and Space Force. AFRL plays an integral role in leading the discovery, development, and integration of affordable warfighting technologies for our air, space, and cyberspace force. With a workforce of more than 11,000 across nine technology areas and 40 other operations across the globe, AFRL provides a diverse portfolio of science and technology ranging from fundamental to advanced research and technology development.
For more information, visit: www.afresearchlab.com.