RF circulator set to transform wireless communications?
Researchers in the US have given the humble RF circulator a makeover. Not only is their prototype smaller, lighter, cheaper and more efficient, it's also claimed to be easily adapted to different frequencies.
The team from the University of Texas at Austin says the device 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 current prototype measures 2cm – more than 75 times smaller than wavelength of operation – with the potential to be scaled down even further to just a few microns. It is based on materials commonly used in integrated circuits such as gold, copper and silicon, making it easy to integrate in the circuit boards of modern communication devices.
"We are changing the paradigm with which isolation and two-way transmission on the same frequency channel can be achieved," said project leader Andrea Alu. "We have built a circulator that does not need magnets or magnetic materials."
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.
With their new device, the researchers have accomplished the same effect, but they replaced the magnetic bias with a traveling wave spinning around the device.
"With this technology, we can incorporate tunable nonreciprocal components in mobile platforms," said Nicholas Estep, a doctoral student in the Department of Electrical and Computer Engineering. "In doing so, we may pave the way to simultaneous two-way communication in the same frequency band, which can free up chunks of bandwidth for more effective use."
What's more, because the design of the circulator is scalable and capable of circuit integration, it can potentially be placed in wireless devices.
"We envision micron-sized circulators embedded in mobile phone technology," Estep continued. "When you consider mobile phone traffic during high demand events such as a football game or a concert, there are enormous implications opened by our technology, including fewer dropped calls and clearer communications."
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