A space-time coding metasurface antenna for efficient and secure communications

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{Photograph} of the space-time-coding metasurface antenna. Credit: Wu et al.

Antennas that may couple guided waves emitted from completely different sources in free house and manipulate these waves are essential to the event of quite a few applied sciences, together with wi-fi communication, optical communication and ranging programs. Metasurfaces, skinny movies made up of a number of parts, have proven promise for creating these kinds of antennas.

Researchers at Metropolis University of Hong Kong and Southeast University have lately created a brand new metasurface antenna that may extract and manipulate guided waves to create desired free-space waves in each the spatial and frequency domains. This antenna, launched in a paper printed in Nature Electronics, combines two completely different analysis developments, particularly amplitude-modulated (AM) leaky-wave antennas and space-time coding methods.

“Our paper is based on the invention of the amplitude-modulated leaky-wave antenna reported in the Ph.D. thesis of Dr. Gengbo WU at the City University of Hong Kong (CityU) and the groundbreaking research on space-time-coding metasurface led by Academician Tie Jun Cui at Southeast University,” Prof. Chi Hou Chan, one of many researchers who carried out the research, informed TechXplore. “The AM leaky-wave antennas are impressed by the amplitude modulation in classical communications concept. “

A key benefit of AM leaky-wave antennas is that their radiation sample can simply be synthesized or tailor-made for particular makes use of, by altering the antenna’s form and construction. As soon as an antenna is fabricated, nevertheless, its radiation traits will usually stay fastened.

“Around the same time when the AM leaky-wave antennas were presented in 2020, Dr. Jun Yan Dai joined the CityU research group from Southeast University for a postdoctoral research fellow appointment,” Prof. Chan stated. “He came from the research group led by Academician Tie Jun Cui and Professor Qiang Cheng and brought us the use of space-time coding, or software control, to dynamically reconfigure the antenna performance.”

A space-time coding metasurface antenna for efficient and secure communications
Measurement setup of the space-time-coding metasurface antenna in a microwave anechoic chamber. Credit: Wu et al.

Area-time coding, or space-time block coding, is a way that permits engineers to transmit a number of copies of a knowledge stream throughout a number of antennas, utilizing the completely different variations of the unique knowledge to switch knowledge extra reliably. Prof. Chan and his colleagues mixed space-time coding methods with AM leaky-wave antenna design to allow the modulation of emitted radiation patterns.

“By combining the two approaches, we achieve a designated radiation characteristic by controlling the on-off sequences and durations of the switches on the leaky-wave antenna through a space-time matrix that can be generated via analytical means,” Prof. Chan defined. “Due to the guided-wave nature of the leaky-wave antenna, unwanted harmonics generated by the switches can be filtered out by the waveguide, leading to sideband suppression. The reported research results are generated with synergistic efforts and complementary expertise by the two research teams at City University of Hong Kong and Southeast University.”

The brand new sideband-free and space-time coding metasurface antennas launched by the researchers in the end enable customers to achieve completely different radiation traits by software program management, with out requiring bodily alterations to the antenna’s construction. Because of this the undesirable sidebands or harmonics that hinder the efficiency of typical antennas primarily based on reconfigurable metasurfaces might be eradicated.

“For example, the same frequency beam steering is achievable with our antenna,” Prof. Chan stated. “As the space-time matrix is linear, different beams radiating at different frequencies can be generated simultaneously by the superposition of different space-time matrices. As the space-time matrix is linear, different beams radiating at different frequencies can be generated simultaneously by the superposition of different space-time matrices.”

Prof. Chan and his colleagues assessed the effectiveness of their antenna design in a sequence of exams and located that it enabled high-efficiency frequency conversion, fundamental-frequency steady beam scanning and the impartial management of a number of harmonics. Sooner or later, their antenna may very well be mixed with completely different base-band modulation schemes to attain extremely environment friendly and safe communications.

“In our next studies, we plan to modify the antenna’s structure to achieve more control over the radiation characteristics, including polarization of the radiated beams,” Prof. Chan added. “One unique feature of the antennas is that we can control the amplitude and phase distributions on the antenna aperture. Therefore, we can create all kinds of radiation characteristics, including linear sweeping of a focused spot along the length or perpendicular to the antenna surface.”

Extra data:
Geng-Bo Wu et al, Sideband-free house–time-coding metasurface antennas, Nature Electronics (2022). DOI: 10.1038/s41928-022-00857-0

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