Researchers in the Cockrell School of Engineering at the University of Texas (UT) Austin have designed an antenna that is able to process incoming and outgoing radio-wave signals more efficiently and without the need for separate bulky and expensive electrical components commonly used in antenna systems. This new technology could lead to significantly faster, cheaper and clearer telecommunications in the future.

Traditionally, the angular patterns for antenna transmission and reception have been assumed to be the same—if the antenna opens a door to let signals out, signals can come back through that same door and leak toward the source. The research team’s design is an antenna that can break reciprocity, or the natural symmetry in radiation that characterizes conventional antennas. By breaking reciprocity, the UT Austin researchers’ antenna can independently control incoming and outgoing signals with great efficiency.

Diagram of a non-reciprocal signal. Image credit: UT Austin.Diagram of a non-reciprocal signal. Image credit: UT Austin.The main advantage of this technological advancement is the possibility of sending out a signal while keeping out noise and echoes that come back toward the antenna, enabling faster data rates and improved connections while requiring less bulky antenna systems. The researchers’ new antenna demonstrated a dramatic difference between transmission and reception capabilities, with reception efficiency from a given direction that is hundreds of times smaller than their transmission efficiency toward the same direction.

In the team’s experiments, the researchers, led by Andrea Alù, associate professor in the Department of Electrical and Computer Engineering, fed the antenna with two signals simultaneously: the radio-frequency signal that they wanted to transmit or receive, and a weak low-frequency modulation signal that slowly changes the properties of the antenna as the radio-frequency signal travels along it. This modulation breaks the inherent symmetry of the antenna in transmission and reception, overcoming the reciprocity constraints.

Currently in the telecommunications field, magnet-based isolators are commonly used as part of antenna systems to prevent received signals from traveling into the transmission amplifier. The researchers believe their new antenna may be an efficient solution to significantly reduce the need of isolators and reduce the size and cost of telecommunication systems.

The team is now looking into how this concept may be extended to other applications such as optics. They envision that by pushing these concepts to higher frequencies, it will be possible to break a similar constraint affecting energy-harvesting devices such as thermophotovoltaic cells. The researchers believe that their antenna experiment, extended to the infrared part of the spectrum, may provide a route toward more efficient energy-harvesting platforms.

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