TINY CIRCULATOR IN PHONES COULD DOUBLE BANDWIDTH

Engineers have found a way to dramatically shrink a critical component of cellphones and other wireless devices. A much smaller, more efficient radio wave circulator has the potential to double the useful bandwidth in wireless communications by enabling full-duplex functionality—meaning devices can transmit and receive signals on the same frequency band at the same time. The researchers did it by ditching the magnets. “We are changing the paradigm with which isolation and two-way transmission on the same frequency channel can be achieved. We have built a circulator that does not need magnets or magnetic materials,” says Andrea Alu, an associate professor at the Cockrell School of Engineering at the University of Texas at Austin.

Since the advent of wireless technology 60 years ago, magnetic-based circulators have been in principle able to provide two-way communications on the same frequency channel, but they are not widely adopted because of the large size, weight, and cost associated with using magnets and magnetic materials.

Freed from a reliance on magnetic effects, the new circulator has a much smaller footprint while also using less expensive and more common materials.

The prototype circulator is 2 centimeters in size—more than 75 times smaller than the wavelength of operation. The circulator may be further scaled down to as small as a few microns, according to the researchers.

The design is based on materials widely used in integrated circuits such as gold, copper, and silicon, making it easier to integrate in the circuit boards of modern communication devices.

HOW IT WORKS

The researchers’ device works by mimicking the way magnetic materials break the symmetry in wave transmission between two points in space, a critical function that allows magnetic circulators to selectively route radio waves.