Tag Archives: #5G

Novel Fast-beam-switching Transceiver Takes 5G to the Next Level (Science and Technology)

Scientists at Tokyo Institute of Technology (Tokyo Tech) and NEC Corporation jointly develop a 28-GHz phased-array transceiver that supports efficient and reliable 5G communications. The proposed transceiver outperforms previous designs in various regards by adapting fast beam switching and leakage cancellation mechanism.

With the recent emergence of innovative technologies, such as the Internet of Things, smart cities, autonomous vehicles, and smart mobility, our world is on the brink of a new age. This stimulates the use of millimeter-wave bands, which have far more signal bandwidth, to accommodate these new ideas. 5G can offer data rates over 10 Gbit/s through the use of these millimeter-waves and multiple-in-multiple-out (MIMO) technology–a technology that employs multiple transmitters and receivers to transfer more data at the same time.

Large-scale phased-array transceivers are crucial for the implementation of these MIMO systems. While MIMO systems boost spectral performance, large-scale phased-array systems face several challenges, such as increased power dissipation and implementation costs. One such critical challenge is latency caused by beam switching time. Beam switching is an important feature that enables the selection of the most optimal beam for each terminal. A design that optimizes beam switching time and device cost is, thus, the need of the hour.

The proposed phased-array transceiver is fabricated using a 65-nm CMOS process and packaged with wafer-level chip-scale package. It is configured in an area as small as 5 × 4.5 mm. © 2021 Symposia on VLSI Technology and Circuits

Motivated by this, scientists from Tokyo Institute of Technology and NEC Corporation in Japan collaborated to develop a 28-GHz phased-array transceiver that supports fast beam switching and high-speed data communication. Their findings will be discussed at the 2021 Symposia on VLSI Technology and Circuits, an international conference that explores emerging trends and innovative concepts in semiconductor technology and circuits.

The proposed design facilitates dual-polarized operation, in which data is transmitted simultaneously through horizontal and vertical-polarized waves. However, one issue with these systems is cross-polarization leakage, which results in signal degradation, especially in the millimeter-wave band. The research team delved into the issue and developed a solution. Prof. Kenichi Okada, who led the research team, says, “Fortunately, we were able to devise a cross-polarization detection and cancellation methodology, using which we could suppress the leakages in both transmit and receive mode.”

One critical feature of the proposed mechanism is the ability to achieve low-latency beam switching and high-accuracy beam control. Static elements control the building blocks of the mechanism, while on-chip SRAM is used to store the settings for different beams (Figure 1). This mechanism leads to fast beam switching with ultra-low latency being achieved. It also enables fast switching in transmit and receive modes due to the use of separate registers for each mode.

Another aspect of the proposed transceiver is its low cost and small size. The transceiver has a bi-directional architecture, which allows for a smaller chip size of 5 × 4.5 mm2 (Figure 2). For a total of 256-pattern beam settings stored within the on-chip SRAM, a beam switching time of only 4 nanoseconds was achieved! Error vector magnitude (EVM)–a measure to quantify the efficiency of digitally modulated signals such as quadrature amplitude modulation (QAM)–was calculated for the proposed transceiver. The transceiver was supported with EVMs of 5.5% in 64QAM and 3.5% in 256QAM.

When compared with state-of-the-art 5G phased-array transceivers, the system has a faster beam switching time and excellent MIMO efficiency. Okada is optimistic about the future of the 28-GHz 5G phased-array transceiver. He concludes, “The technology we developed for the 5G NR network supports high-volume data streaming with low latency. Thanks to its rapid beam switching capabilities, it can be used in scenarios where enhanced multi-user perception is required. This device sets the stage for a myriad of applications, including machine connectivity and the construction of smart cities and factories.”

This research is supported by the Ministry of Internal Affairs and Communications in Japan (JPJ000254).

Featured image: Large volume SRAM and lookup table are used for supporting 256 beam settings. The mechanism supports fast switching in transmit (TX) and receive (RX) mode with direct external TX/RX enable pins. © 2021 Symposia on VLSI Technology and Circuits


  • Authors: Jian Pang, Zheng Li, Xueting Luo, Joshua Alvin, Kiyoshi Yanagisawa, Yi Zhang, Zixin Chen, Zhongliang Huang, Xiaofan Gu, Weichu Chen, Yun Wang, Dongwon You, Zheng Sun, Yuncheng Zhang, Hongye Huang, Naoki Oshima, Keiichi Motoi, Shinichi Hori, Kazuaki Kunihiro, Tomoya Kaneko, Atsushi Shirane, and Kenichi Okada
  • Session: Session 11 Advanced Wireless for 5G, C11-2 (June 17,8:50JST)
  • Session Title: A Fast-Beam-Switching 28-GHz Phased-Array Transceiver Supporting Cross-Polarization Leakage Self-Cancellation
  • Conference: 2021 Symposia on VLSI Technology and Circuits
  • Affiliations: Tokyo Institute of Technology, NEC Corporation

Provided by Tokyo Institute of Technology

Enhanced Ceramics Could Play Pivotal Role in Advancing 5G Technology (Engineering)

Some 5G technologies still considered the wild west in material, design development

5G, or the fifth-generation technology standard for broadband cellular networks, is touted as having finally arrived for ultrafast download speeds, an end to dropped calls and buffering, and greater connectivity to advance autonomous vehicle development, remote surgery, and the Internet of Things.

In truth, 5G technology adoption is still in its early stages, according to Michael Hill, technical director of Skyworks Solutions, a California-based advanced-semiconductor company. In their paper, published in Applied Physics Letters, by AIP Publishing, Hill and his colleagues provide an overview on nascent 5G technologies and show how enhancing ceramic materials could play a pivotal role in 5G development.

5G operates in two frequency bands: 3-6 gigahertz for long-distance links and a much higher frequency band in the millimeter wave region (20-100 GHz) for ultrafast data speeds.

Accommodating the lower frequency band, closer to the 4G spectral regions, is less problematic than the significant changes needed to fully realize 5G capability in the higher frequency ranges. For example, frequency type is tied to overall signal strength. The higher the frequency, the shorter the distance the wave can travel.

Ceramic materials have long been used in wireless communications network technologies for both mobile devices and base stations. Enhancing ceramics, therefore, has been a central focus in improving 5G capability. For their part, Hill’s research group has developed a ceramic to enhance a device that is critical for 5G applications, called a circulator.

Typically made of insulating ceramic materials based on yttrium iron garnet, circulators are three-port devices that serve as traffic circles to keep the signal flowing in one direction and enable a receiver and a transmitter to share the same antenna.

To significantly increase the energy density to accommodate the higher frequencies, the researchers have partially replaced yttrium with bismuth, a heavy element that increases the dielectric constant of the ceramic. The bismuth substitutions also enable the miniaturization of circulators.

As the 5G technology battle continues to heat up, circulators could be supplanted by high-power gallium nitride-based switches, which shows just how early the stage still is for 5G technology development.

“Millimeter-wave technology is likely to be the wild west for some time, as one technology may dominate only to be quickly supplanted by a different technology,” Hill said.

The article “Perspective on ceramic materials for 5G wireless communication systems” is authored by Michael David Hill, David Bowie Cruickshank, and Iain MacFarlane. The article will appear in Applied Physics Letters on March 23, 2021 (DOI: 10.1063/5.0036058). After that date, it can be accessed at https://aip.scitation.org/doi/10.1063/5.0036058.

Featured image: Advantages of 5G systems © Skyworks Solutions

Provided by American Institute of Physics

Artificial Emotional Intelligence: A Safer, Smarter Future with 5G and Emotion Recognition

Researchers introduce a 5G-enabled, AI-based emotion detection system and discuss its operation, applications, and potential security issues.

The combination of new 5G communication technologies with AI-based systems are ushering in a “smart generation” of vehicles, drones, and even entire cities. Now, researchers take things one step further by introducing a 5G-assisted emotion detection system that uses wireless signals and body movement. In their latest publication, they outline its working principle, application prospects, and potential security threats, highlighting the need for a robust, impregnable AI algorithm to drive it.

With the advent of 5G communication technology and its integration with AI, we are looking at the dawn of a new era in which people, machines, objects, and devices are connected like never before. This smart era will be characterized by smart facilities and services such as self-driving cars, smart UAVs, and intelligent healthcare. This will be the aftermath of a technological revolution.
But the flip side of such technological revolution is that AI itself can be used to attack or threaten the security of 5G-enabled systems which, in turn, can greatly compromise their reliability. It is, therefore, imperative to investigate such potential security threats and explore countermeasures before a smart world is realized.

In a recent study published in IEEE Network, a team of researchers led by Prof. Hyunbum Kim from Incheon National University, Korea, address such issues in relation to an AI-based, 5G-integrated virtual emotion recognition system called 5G-I-VEmoSYS, which detects human emotions using wireless signals and body movement. “Emotions are a critical characteristic of human beings and separates humans from machines, defining daily human activity. However, some emotions can also disrupt the normal functioning of a society and put people’s lives in danger, such as those of an unstable driver. Emotion detection technology thus has great potential for recognizing any disruptive emotion and in tandem with 5G and beyond-5G communication, warning others of potential dangers,” explains Prof. Kim. “For instance, in the case of the unstable driver, the AI enabled driver system of the car can inform the nearest network towers, from where nearby pedestrians can be informed via their personal smart devices.”

The virtual emotion system developed by Prof. Kim’s team, 5G-I-VEmoSYS, can recognize at least five kinds of emotion (joy, pleasure, a neutral state, sadness, and anger) and is composed of three subsystems dealing with the detection, flow, and mapping of human emotions. The system concerned with detection is called Artificial Intelligence-Virtual Emotion Barrier, or AI-VEmoBAR, which relies on the reflection of wireless signals from a human subject to detect emotions. This emotion information is then handled by the system concerned with flow, called Artificial Intelligence-Virtual Emotion Flow, or AI-VEmoFLOW, which enables the flow of specific emotion information at a specific time to a specific area. Finally, the Artificial Intelligence-Virtual Emotion Map, or AI-VEmoMAP, utilizes a large amount of this virtual emotion data to create a virtual emotion map that can be utilized for threat detection and crime prevention.

A notable advantage of 5G-I-VEmoSYS is that it allows emotion detection without revealing the face or other private parts of the subjects, thereby protecting the privacy of citizens in public areas. Moreover, in private areas, it gives the user the choice to remain anonymous while providing information to the system. Furthermore, when a serious emotion, such as anger or fear, is detected in a public area, the information is rapidly conveyed to the nearest police department or relevant entities who can then take steps to prevent any potential crime or terrorism threats.

However, the system suffers from serious security issues such as the possibility of illegal signal tampering, abuse of anonymity, and hacking-related cyber-security threats. Further, the danger of sending false alarms to authorities remains.

While these concerns do put the system’s reliability at stake, Prof. Kim’s team are confident that they can be countered with further research. “This is only an initial study. In the future, we need to achieve rigorous information integrity and accordingly devise robust AI-based algorithms that can detect compromised or malfunctioning devices and offer protection against potential system hacks,” explains Prof. Kim, “Only then will it enable people to have safer and more convenient lives in the advanced smart cities of the future.”

Featured image: With 5G communication technology and new AI-based systems such as emotion recognition systems, smart cities are all set to become a reality; but these systems need to be honed and security issues need to be ironed out before the smart reality can be realized. Photo Courtesy: macrovector on Freepik

Reference: H. Kim, J. Ben-Othman, L. Mokdad, J. Son and C. Li, “Research Challenges and Security Threats to AI-Driven 5G Virtual Emotion Applications Using Autonomous Vehicles, Drones, and Smart Devices,” in IEEE Network, vol. 34, no. 6, pp. 288-294, November/December 2020.
doi: 10.1109/MNET.011.2000245

Provided by Incheon National University

Pushed to the Limit: A CMOS-based Transceiver For Beyond 5G Applications at 300 GHz (Engineering)

Scientists at Tokyo Institute of Technology and NTT Corporation develop a novel CMOS-based transceiver for wireless communications at the 300 GHz band, enabling future beyond-5G applications. Their design addresses the challenges of operating CMOS technology at its practical limit and represents the first wideband CMOS phased-array system to operate at such elevated frequencies.

Communication at higher frequencies is a perpetually sought-after goal in electronics because of the greater data rates that would be possible and to take advantage of underutilized portions of the electromagnetic spectrum. Many applications beyond 5G, as well as the IEEE802.15.3d standard for wireless communications, call for transmitters and receivers capable of operating close to or above 300 GHz.

Unfortunately, our trusty CMOS technology is not entirely suitable for such elevated frequencies. Near 300 GHz, amplification becomes considerably difficult. Although a few CMOS-based transceivers for 300 GHz have been proposed, they either lack enough output power, can only operate in direct line-of-sight conditions, or require a large circuit area to be implemented.

To address these issues, a team of scientists from Tokyo Institute of Technology (Tokyo Tech), in collaboration with NTT Corporation (NTT), proposed an innovative design for a 300 GHz CMOS-based transceiver (Figure 1). Their work will be presented in the Digests of Technical Papers in the 2021 IEEE ISSCC (International Solid-State Circuits Conference), a conference where the latest advances in solid-state and integrated circuits are exposed.

One of the key features of the proposed design is that it is bidirectional; a great portion of the circuit, including the mixer, antennas, and local oscillator, is shared between the receiver and the transmitter (Figure 2). This means the overall circuit complexity and the total circuit area required are much lower than in unidirectional implementations.

Figure 2. Proposed bidirectional phased-array transceiver architecture © Tokyo Institute of Technology

Another important aspect is the use of four antennas in a phased array configuration. Existing solutions for 300 GHz CMOS transmitters use a single radiating element, which limits the antenna gain and the system’s output power. An additional advantage is the beamforming capability of phased arrays, which allows the device to adjust the relative phases of the antenna signals to create a combined radiation pattern with custom directionality. The antennas used are stacked “Vivaldi antennas,” which can be etched directly onto PCBs, making them easy to fabricate.

The proposed transceiver uses a subharmonic mixer, which is compatible with a bidirectional operation and requires a local oscillator with a comparatively lower frequency. However, this type of mixing results in low output power, which led the team to resort to an old yet functional technique to boost it. Professor Kenichi Okada from Tokyo Tech, who led the study, explains: “Outphasing is a method generally used to improve the efficiency of power amplifiers by enabling their operation at output powers close to the point where they no longer behave linearly—that is, without distortion. In our work, we used this approach to increase the transmitted output power by operating the mixers at their saturated output power.” Another notable feature of the new transceiver is its excellent cancellation of local oscillator feedthrough (a “leakage” from the local oscillator through the mixer and onto the output) and image frequency (a common type of interference for the method of reception used).

The entire transceiver was implemented in an area as small as 4.17 mm2. It achieved maximum rates of 26 Gbaud for transmission and 18 Gbaud for reception, outclassing most state-of-the-art solutions. Excited about the results, Okada remarks: “Our work demonstrates the first implementation of a wideband CMOS phased-array system that operates at frequencies higher than 200 GHz.” Let us hope this study helps us squeeze more juice out of CMOS technology for upcoming applications in wireless communications!

Featured image: Chip micrograph of 300 GHz-band phased-array transceiver implemented by 65 nm CMOS © Tokyo Institute of Technology

Reference: Ibrahim Abdo, Carrel da Gomez, Chun Wang, Kota Hatano, Qi Li, Chenxin Liu, Kiyoshi Yanagisawa, Ashbir Aviat Fadila, Jian Pang, Hiroshi Hamada, Hideyuki Nosaka, Atsushi Shirane, Kenichi Okada, “A 300GHz-Band Phased-Array Transceiver Using Bi-Directional Outphasing and Hartley Architecture in 65nm CMOS
[Technical paper are released at February 5 5:00 PM (PST), Live Q&As : February 17th 8:38 AM PST]”, Proceedings of the 2021 IEEE ISSCC (International Solid-State Circuits Conference), Session 22.2: Terahertz for Communication and Sensing
February 17th 8:30 AM (PST), 2021 IEEE International Solid-State Circuits Conference (ISSCC 2021) https://underline.io/log-in?eventId=74&redirectUrl=%2Fevents%2F74%2Fsessions%2F2402%2Flecture%2F13632-22.2—a-300ghz-band-phased-array-transceiver-using-bi-directional-outphasing-and-hartley-architecture-in-65nm-cmos

Provided by Tokyo Institute of Technology

RUDN University Mathematicians Developed New Approach to 5g Base Stations Operation (Engineering)

Mathematicians from RUDN University suggested and tested a new method to assess the productivity of fifth-generation (5G) base stations. The new technology would help get rid of mobile access stations and even out traffic fluctuations. The results of the study were published in the IEEE Conference Publication.

Stations of the new 5G New Radio (NR) communication standard developed by the 3GPP consortium are expected to shortly be installed in large quantities all over the world. First of all, the stations will be deployed in places with high traffic use and at public event locations (e.g. shopping malls, city squares, or stadiums). In these conditions, the number of active communication sessions continually changes, and such traffic fluctuations can dramatically reduce network capacity. Traditionally, this issue has been solved with mobile stations (drones or cars), but they cannot be used in a closed space such as a shopping mall. Moreover, they are unable to even out traffic fluctuations on the sub-minute scale (i.e. within periods less than 1 minute). A team of mathematicians from RUDN University suggested a 5G network deployment scheme that provides for the mitigation of traffic fluctuations on the sub-minute level and can be rolled out in closed spaces.

“The 5G NR technology promises exceptionally high speed on the final mile–a channel that connects a user’s device with a provider’s access point. The connection is expected to be extremely fast within the millimeter waves range. The new technology is supposed to satisfy the growing needs of users. Our approach could help deploy 5G in busy public places and effectively even out traffic fluctuations,” explained Anastasia Daraseliya, a postgraduate student at the Institute for Applied Mathematics and Telecommunications, RUDN University.

The idea suggested by RUDN mathematicians lies in using two technologies at once: NR and the so-called WiGig–60-gigahertz Wi-Fi with a data transmission rate up to 7 Gb/sec. By aggregating a licensed and a non-licensed band spectrum, one could shed some of the load to the non-licensed band and thus increase the transmission speed. Both technologies operate in the millimeter waves range and therefore are adjusted to each other by default. The team also assumed that both technologies would be widely supported by modern-day and future devices.

The team studied the joint user traffic query serving by base stations using a combination of NR and WiGig and analyzed the future applicability of this system. To do so, they used several methods of stochastic geometry, Markovian chain theory, and queueing theory. The team described the methodology of interaction between the two standards in one base station and concluded that the new approach would support continuous 5G communication in busy public places without losing transmission capacity even in cases of sub-minute traffic drops

“Having determined the density of base station and taking into account the density of user devices, we suggested a performance assessment structure for joint use of NR and WiGig. Although in the model the two systems are located close to each other, they do not exchange data. Therefore, such a structure can be deployed in any necessary configuration depending on conditions and requirements,” added Anastasia Daraseliya from RUDN Unviersity.

Featured image: Mathematicians from RUDN University suggested and tested a new method to assess the productivity of fifth-generation (5G) base stations. The new technology would help get rid of mobile access stations and even out traffic fluctuations. © RUDN University

Reference: A. Daraseliya, M. Korshykov, E. Sopin, D. Moltchanov, Y. Koucheryavy and K. Samouylov, “Handling Overflow Traffic in Millimeter Wave 5G NR Deployments using NR-U Technology,” 2020 IEEE 31st Annual International Symposium on Personal, Indoor and Mobile Radio Communications, London, United Kingdom, 2020, pp. 1-7. URL: http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=9217313&isnumber=9217048
doi: 10.1109/PIMRC48278.2020.9217313

Provided by RUDN University

Newly Developed GaN based MEMS Resonator Operates Stably Even at High Temperature (Material Science)

Promising as a highly sensitive oscillator toward 5G communication.

Liwen Sang, independent scientist at International Center for Materials Nanoarchitectonics, National Institute for Materials Science (also JST PRESTO researcher) developed a MEMS resonator that stably operates even under high temperatures by regulating the strain caused by the heat from gallium nitride (GaN).

Figure 1. The device processing for the double-clamped GaN bridge resonator on Si substrate. Figure Caption: (1) The as-grown GaN epitaxial film on Si substrate. Except for the AlN buffer layer, no strain removal layer is used. (2) Spin coating of the photoresist on the GaN-on-Si sample. (3) Laser lithography to define the pattern for the double clamped bridge configuration. (4) Plasma etching to remove the GaN layer without photo resist. (5) Chemical etching to release Si under the GaN layer. Therefore, the air gap is formed. (6) The final device structure of the double clamped bridge resonator. We use the laser doppler method to measure the frequency shift and resolution under different temperatures. © Liwen Sang

High-precision synchronization is required for the fifth generation mobile communication system (5G) with a high speed and large capacity. To that end, a high-performance frequency reference oscillator which can balance the temporal stability and temporal resolution is necessary as a timing device to generate signals on a fixed cycle. The conventional quartz resonator as the oscillator has the poor integration capability and its application is limited. Although a micro-electromechanical system (MEMS)*1 resonator can achieve a high temporal resolution with small phase noise and superior integration capability, the silicon (Si)-based MEMS suffers from a bad stability at higher temperatures.

In the present study, a high-quality GaN epitaxial film was fabricated on a Si substrate using metal organic chemical vapor deposition (MOCVD)*2 to fabricate the GaN resonator. The strain engineering was proposed to improve the temporal performance. The strain was achieved through utilizing the lattice mismatch and thermal mismatch between GaN and Si substrate. Therefore, GaN was directly grown on Si without any strain-removal layer. By optimizing the temperature decrease method during MOCVD growth, there was no crack observed on GaN and its crystalline quality is comparable to that obtained by the conventional method of using a superlattice strain-removal layer.

Figure 2. (a) The temperature coefficient of frequency (TCF) of the GaN resonator at different temperature; (b) The quality factor of the GaN resonator at different temperature
The temporal stability of a resonator is defined by temperature coefficient of frequency (TCF). TCF indicates a change of the resonance frequency with changing temperature. For the Si MEMS resonator, its intrinsic TCF is ~ -30ppm/K. Several methods were proposed to reduce the TCF of Si resonator, but the quality factors of the system were greatly degraded. The quality factor of a resonator in the system can be used to determine the frequency resolution. A high quality factor is required for the accurate frequency reference. The developed GaN resonator in this work can simultaneously achieve a low TCF and high quality factor up to 600 K. The TCF is as low as -5 ppm/K. The quality factor is more than 105, which is the highest one ever reported in GaN system. © Liwen Sang

The developed GaN-based MEMS resonator was verified to operate stably even at 600K. It showed a high temporal resolution and good temporal stability with little frequency shift when the temperature was increased. This is because the internal thermal strain compensated the frequency shift and reduce the energy dissipation. Since the device is small, highly sensitive and can be integrated with CMOS technology, it is promising for the application to 5G communication, IoT timing device, on-vehicle applications, and advanced driver assistance system.

The research was supported by JST’s Strategic Basic Research Program, Precursory Research for Embryonic Science and Technology(PRESTO). This result was presented at the IEEE International Electron Devices Meeting (IEDM2020) held online on December 12-18, 2020, titled “Self-Temperature-Compensated GaN MEMS Resonators through Strain Engineering up to 600 K.”

(1) Micro-electro mechanical systems (MEMS)

A device where mechanical components, sensors, actuators, and electrical circuit are integrated on a substrate, such as semiconductor, glass, or organic material through microfabrication technology. For the main component, three-dimensional shape and movable structures are built through etching.

(2) Metal organic chemical vapor deposition (MOCVD)

A useful crystal growth method to build a wafer for compound semiconductors. Organometallic compounds of the Group III and Group V are simultaneously provided to the heated crystalline surface of the substrate to achieve epitaxial growth.

Provided by Japan Science and Technology Agency

Ultrathin Spray-applied MXene Antennas Are Ready for 5G (Material Science)

Drexel’s MXene technology reaches telecommunications performance benchmarks.

New antennas so thin that they can be sprayed into place are also robust enough to provide a strong signal at bandwidths that will be used by fifth-generation (5G) mobile devices. Performance results for the antennas, which are made from a new type of two-dimensional material called MXene, were recently reported by researchers at Drexel University and could have rammifications for mobile, wearable and connected “internet of things” technology.

Drexel University researchers have produced flexible, spray-applied antennas made from a two-dimensional material called MXene, that have reached performance measures on par with current telecommunications technology. ©Drexel University (Meikang Han)

The MXene antennas, which have been in development at Drexel for just over two years, are already performing nearly as well as the copper antennas found in most mobile devices on the market today, but with the benefit of being just a fraction of their thickness and weight.

“This combination of communications performance with extreme thinness, flexibility and durability sets a new standard for antenna technology,” said Yury Gogotsi, PhD, Distinguished University and Bach professor of Materials Science and Engineering in Drexel’s College of Engineering, who is the lead author of a paper on the MXene antennas recently published in the journal Advanced Materials. “While copper antennas have been the best in terms of performance for quite some time, their physical limitations have prevented connected and mobile technology from making the big leaps forward that many have predicted. Due to their unique set of characteristics MXene antennas could play an enabling role in the development of IoT technology.”

While mobile communications companies currently are on the cusp of introducing 5G technology, which could capitalize on an less-used portion of the telecommunication spectrum to enable faster data transmission, it will likely become the standard range of operation for new technology.

Beyond reaching performance capabilities, antennas for devices of the future must also be able to acquit themselves well in a variety of environments outside of the circuitboards of phones and computers. According to Gogotsi, this makes MXene an appealing material for new antennas because it can be spray applied, screen printed or inkjet-printed onto just about any substrate and remains flexible without sacrificing performance.

“Generally copper antenna arrays are manufactured by etching printed circuit boards, this is a difficult process to undertake on a flexible substrate,” said Meikang Han, PhD, a post-doctoral researcher at the A.J. Drexel Nanomaterials Institute who contributed to the research.”This puts MXene at a distinct advantage because it disperses in water to produce an ink, which can be sprayed or printed onto building walls or flexible substrates to create antennas.”

Ultrathin, spray-applied MXene antennas, developed by researchers at Drexel University, performs on par with antennas currently used in fifth-generation telecommunications technology. ©Drexel University (Meikang Han)

In the paper, Gogotsi and his collaborators, including Professor Gary Friedman, PhD, and Kapil Dandekar, PhD, E. Warren Colehower Chair Professor of the Electrical and Computer Engineering Department in Drexel’s College of Engineering, reported on the performance of three sets of spray-coated MXene antennas, which were between 7-14 times thinner and 15-30 times lighter than a similar copper antenna – even thinner than a coat of paint. They tested the antennas in both lab and open environments for key performance measures of how efficiently the antenna converts power into directed waves – gain, radiation efficiency and directivity. And they did the testing at the three radio frequencies commonly used for telecommunication, including one in the target frequency of operation for 5G devices.

In each instance, the MXene antennas performed within 5% percent of copper antennas, with performance increasing with thickness of the antenna. The best performing MXene patch antenna, about one-seventh the thickness of standard copper antennas, was 99% as efficient as a copper antennas operating at 16.4 GHz frequency in an open environment. MXenes were also 98% as effective as their copper counterparts operating in the 5G bandwidth.

Their performance exceeded that of several other new materials being considered for antennas, including silver ink, carbon nanotubes and graphene. And, siginificantly, these performance numbers did not waiver when the MXene antennas were subjected to as many as 5,000 bending cycles – a mark of durability that far surpasses its peer materials.

“MXene’s scalability and environmental sustainability in manufacturing has been well estabilished, for this material to now achieve performance goals on pace with the best materials on the market today is certainly a significant development,” Gogotsi said. “As we continue to test various coating patterns and techniques while additionally optimizing the composition of MXene materials, I expect their performance to continue to improve.”

References: Meikang Han, Yuqiao Liu, Roman Rakhmanov, Christopher Israel, Md Abu Saleh Tajin, Gary Friedman, Vladimir Volman, Ahmad Hoorfar, Kapil R. Dandekar, Yury Gogotsi. Solution‐Processed Ti 3 C 2 T x MXene Antennas for Radio‐Frequency Communication. Advanced Materials, 2020; 2003225 DOI: 10.1002/adma.202003225

Provided by Drexel University