More Like this

1. Conformal leaky-wave antennas for wireless terahertz communications

   https://doi.org/10.1038/s44172-023-00067-2  

   Guerboukha, Hichem; Shrestha, Rabi; Neronha, Joshua; Fang, Zhaoji; Mittleman, Daniel M. (December 2023, Communications Engineering)

   Abstract Future generations of wireless systems are expected to combine the use of high-frequency bands (the terahertz range) with smart interconnected devices (the Internet of Things). To realize this ambitious merging, systems will require antennas that can be mounted on nonplanar objects while generating highly directional beams. Here, we study conformal THz leaky-wave antennas at THz frequencies. We find a rich set of behaviors accessible at THz frequencies dictated by the interplay among the geometrical parameters and the wavelength. We develop simple models to describe the relevant physics, which we verify by an experimental implementation. We also demonstrate data transmission using a conformal THz antenna that can generate multiple high-gain beams with low bit error rates for increased coverage of THz wireless links. 

   more » « less
2. PropagationMeasurementsandPathLossModelsfor sub-THz inUrbanMicrocells

   Yunchou Xing, Theodore S. (June 2021, IEEE International Conference on Communications)

   Terahertz frequency bands will likely be used for the next-generation wireless communication systems to provide data rates of hundreds of Gbps or even Tbps because of the wide swaths of unused and unexplored spectrum. This paper presents two outdoor wideband measurement campaigns in downtown Brooklyn (urban microcell environment) in the sub-THz band of 140 GHz with TX-RX separation distance up to 100 m: i) terrestrial urban microcell measurement campaign, and ii) rooftop surrogate satellite and backhaul measurement campaign. Outdoor omnidirectional and directional path loss models for both line-of-sight and non-line-of-sight scenarios, as well as foliage loss (signal attenuation through foliage), are provided at 140 GHz for urban microcell environments. These measurements and models provide an understanding of both the outdoor terrestrial (e.g., 6G cellular and backhaul) and non-terrestrial (e.g., satellite and unmanned aerial vehicle communications) wireless channels, and prove the feasibility of using THz frequency bands for outdoor fixed and mobile cellular communications. This paper can be used for future outdoor wireless system design at frequencies above 100 GHz. 

   more » « less
3. Ultrafast modulation of terahertz waves using on-chip dual-layer near-field coupling

   https://doi.org/10.1364/OPTICA.469461  

   Zhang, Yaxin; Ding, Kesen; Zeng, Hongxin; Kou, Wei; Zhou, Tianchi; Zhou, Hongji; Gong, Sen; Zhang, Ting; Wang, Lan; Liang, Shixiong; et al (November 2022, Optica)

   As a key potential component of future sixth-generation (6G) communication systems, terahertz (THz) technology has received much attention in recent years. However, a lack of effective high-speed direct modulation of THz waves has limited the development of THz communication technology. Currently, most high-speed modulators are based on photonic systems that can modulate electromagnetic waves with high speed using sophisticated optoelectronic conversion techniques. Yet, they usually suffer from low conversion efficiency of light to the THz range, resulting in low output power of the modulated THz waves. Here, we describe a guided-wave modulator for THz signals whose performance nearly matches that of existing in-line fiber-optic modulators. Our results demonstrate a maximum modulation depth greater than 20 dB (99%) and a maximum sinusoidal modulation speed of more than 30 GHz, with an insertion loss around 7 dB. We demonstrate the capabilities of this modulator in a point-to-point communication link with a 25 Gbit/s modulation speed. Our modulator design, based on near-field coupling of a THz transmission line to a single resonant meta-element, represents a powerful improvement for on-chip integrated high-performance THz devices. 

   more » « less
4. Jamming a terahertz wireless link

   https://doi.org/10.1038/s41467-022-30723-8  

   Shrestha, Rabi; Guerboukha, Hichem; Fang, Zhaoji; Knightly, Edward; Mittleman, Daniel M. (June 2022, Nature Communications)

   Abstract As the demand for bandwidth in wireless communication increases, carrier frequencies will reach the terahertz (THz) regime. One of the common preconceived notions is that, at these high frequencies, signals can radiate with high directivity which inherently provides more secure channels. Here, we describe the first study of the vulnerability of these directional links to jamming, in which we identify several features that are distinct from the usual considerations of jamming at low frequencies. We show that the receiver’s use of an envelope detector provides the jammer with the ability to thwart active attempts to adapt to their attack. In addition, a jammer can exploit the broadband nature of typical receivers to implement a beat jamming attack, which allows them to optimize the efficacy of the interference even if their broadcast is detuned from the frequency of the intended link. Our work quantifies the increasing susceptibility of broadband receivers to jamming, revealing previously unidentified vulnerabilities which must be considered in the development of future wireless systems operating above 100 GHz. 

   more » « less
5. Real-time programmable metasurface for terahertz multifunctional wave front engineering

   https://doi.org/10.1038/s41377-023-01228-w  

   Lan, Feng; Wang, Luyang; Zeng, Hongxin; Liang, Shixiong; Song, Tianyang; Liu, Wenxin; Mazumder, Pinaki; Yang, Ziqiang; Zhang, Yaxin; Mittleman, Daniel M. (December 2023, Light: Science & Applications)

   Abstract Terahertz (THz) technologies have become a focus of research in recent years due to their prominent role in envisioned future communication and sensing systems. One of the key challenges facing the field is the need for tools to enable agile engineering of THz wave fronts. Here, we describe a reconfigurable metasurface based on GaN technology with an array-of-subarrays architecture. This subwavelength-spaced array, under the control of a 1-bit digital coding sequence, can switch between an enormous range of possible configurations, providing facile access to nearly arbitrary wave front control for signals near 0.34 THz. We demonstrate wide-angle beam scanning with 1° of angular precision over 70 GHz of bandwidth, as well as the generation of multi-beam and diffuse wave fronts, with a switching speed up to 100 MHz. This device, offering the ability to rapidly reconfigure a propagating wave front for beam-forming or diffusively scattered wide-angle coverage of a scene, will open new realms of possibilities in sensing, imaging, and networking. 

   more » « less