Olav Breinbjerg received the M.Sc. and Ph.D. degrees in electrical engineering from the Technical University of Denmark (DTU) in 1987 and 1992, respectively. He was on the Faculty of DTU’s Department of Electrical Engineering as Assistant Professor from 1991 to 1995, Associate Professor from 1995 to 2005, and Full Professor from 2006 to 2021. From 1997 to 2021 he was also Head of the Electromagnetic Systems Group and the DTU-ESA Spherical Near-Field Antenna Test Facility, and he founded the DTU Electromagnetic Test Centre. He resigned his position at DTU in 2021 and founded ElMaReCo for independent research consultancy. Olav Breinbjerg was a Visiting Scientist at Rome Laboratory in 1988, a Fulbright Research Scholar at the University of Texas at Austin in 1995, and a Visiting Professor at the University of Siena in 2011 and 2022. His research is generally in applied electromagnetics - and particularly in antennas, antenna measurements, computational techniques, and scattering - for applications in wireless communication and sensing technologies. He is the author or co-author of more than 75 journal papers, 250 conference papers, and 250 technical reports. Dr. Breinbjerg was a recipient of a U.S. Fulbright Research Award in 1995, the 2001 AEG Elektron Foundation's Award, the 2003 DTU Student Union's Teacher of the Year Award, the 2013 and 2015 European School of Antennas Teacher of the Year Awards, the 2020 Hans Christian Ørsted Award, and the 2023 AMTA Distinguished Achievement Award. Dr. Breinbjerg is Fellow of AMTA, Fellow of IEEE, Knight of the Order of Dannebrog, and the 2024-2025 AMTA Distinguished Speaker.

Jasmin Grosinger is an Associate Professor at the Institute of Microwave and Photonic Engineering at Graz University of Technology in Austria. Her research is focused on sustainable wireless electronics and systems. Jasmin also works as a Visiting Associate Professor at the Graduate School of Engineering at Tohoku University, Japan. She is a Senior Member of IEEE and has co-authored several peer-reviewed publications, book chapters, and invention disclosures. Jasmin serves as an Associate Editor for IEEE Microwave and Technology Letters and as a Guest Editor for IEEE Microwave Magazine. Additionally, she chairs the Wireless Power Technologies (WPT) Journal Exploration Working Group (IEEE WPT Initiative) and is a member of the IEEE Microwave Theory and Technology Society (MTT-S) Technical Committees 25 (Wireless Power Transfer and Energy Conversion) and 26 (RFID, Wireless Sensors, and IoT). Jasmin has been recognized as a Distinguished Microwave Lecturer of MTT-S and is an Elected Voting Member of its Administrative Committee, chairing the Meetings and Symposia Committee in 2024.

The ongoing digital transition has the potential to revolutionize our economy, society, and daily lives. Digitalization is changing how we communicate, access information, learn, and conduct business. It is driven by the vast new opportunities it creates. The Internet of Things (IoT) is one example of digitalization, which combines multiple digital technologies with the potential to revolutionize industries and society. Wireless devices, sensors, and wearables have been adapted due to smartphones and other internet-connected devices, driving their growth. There are expected to be over 75 billion IoT-connected devices by 2025 [1]. The expansion of digital infrastructure must be kept in line with the aims of the green transition, particularly regarding the energy consu mption and the environmental footprint of IoT-connected devices. The green transition is necessary to mitigate the consequences of climate change and environmental degradation. However, the costs associated with the green transition can significantly hinder change. Yet, both the green and digital transitions can reinforce each other. For example, cities are responsible for approximately 75% of global CO2 emissions [1]. Smart cities and communities exploiting digitalization using the Internet of Things are possible solutions to reduce these emissions and show how the green and digital twin transitions can take place holistically and systematically.

Sensing by means of reflected signal patterns [2] can significantly contribute to achieving the green and digital twin transitions. The sensor approach uses the antenna as the sensor transducer, with no additional power and hardware costs. It allows the addition of sensing capabilities into wireless devices regardless of their communication technology and operating frequency. The wireless device – consisting of an antenna and chip – can perceive its environment using a specifically designed sensor antenna. This talk details a custom-built ultra- high frequency (UHF) radio-frequency identification (RFID) sensor transponder (tag) based on signal-pattern- based sensing [2]. A literature review on antenna-based RFID sensor tags shows prototypes using analog modulation concepts to enable antenna-based sensing and high sensor system performance. The UHF RFID sensor system performance is affected by two significant factors. The system performance degrades due to a non- sufficiently high wireless power transfer towards the batteryless tag chip. Additionally, the sensor system performance degrades due to a dependence of the detected sensor data on the distance between the reader and tag and, thus, on the wireless channel. The sensor tag presented in Figure 1 uses signal patterns to communicate the sensor state, i.e., a specific tag signal pattern relates to a set of discrete sensor states using a sophisticated analog modulation concept. As a result, the system constantly offers a high wireless power transfer and setup independence. Figure 1.Signal-pattern-based UHF RFID sensor tag [2]: The sensor tag uses the antenna as a sensing device and consists of a dipole antenna and an NXP UCODE 7 chip to monitor a water canister’s full or empty status.

References
[1] S. Muench, E. Stoermer, K. Jensen, T. Asikainen, M. Salvi, and F. Scapolo, “Towards a Green & Digital Future,” 2022, doi: 10.2760/977331.
[2] L. Görtschacher and J. Grosinger, “UHF RFID Sensor System Using Tag Signal Patterns: Prototype System,” IEEE Antennas and Wireless Propagation Letters, 18, 10, September 2019, pp. 2209–2213, doi: 10.1109/LAWP.2019.

Prof. SIM Chow-Yen-Desmond was born in Singapore in Feb. 1971. He received a B.S. degree in electrical and electronic engineering from the University of Leicester, Leicester, UK, in 1998, and a Ph.D. degree in the radio system group from the University of Leicester, in 2003. Since 2003/07, he has been with the Feng Chia University, Taiwan, where he is currently a Distinguished Professor since 2017/08. His research interests mainly include small antenna designs and RFID applications, focusing on 5G sub-6GHz/mmWave antenna, RFID antenna, antenna array, and laptop antenna. He has published over 200 SCI journal papers based on the abovementioned research. Prof. Sim is a Fellow of the Institute of Engineering and Technology (FIET), a Senior Member of the IEEE Antennas and Propagation Society (APS), and a Life Member of the IAET. He was an Associate Editor (AE) of the IEEE Access during 2015/08-2022/01, and has served as the AE of IEEE AWPL during 2017/08-2023/08. He is now serving as the AE of IEEE Journal of RFID, IEEE Open Journal of Antenna and Propagation, and International Journal of RF and Microwave Computer-Aided Engineering. He has served as a member of organizing committees of many conferences, such as General Chair/Co-Chair and TPC Chair/Member, etc. He was invited to serve as the Workshop/Tutorial/Invited Speaker in many conferences. He has served as the Chapter Chair of the IEEE AP-Society, Taipei Chapter (2016/2017) and the founding Chapter Chair of the IEEE Council of RFID, Taipei Chapter (2017-2020). He received the IEEE APS Outstanding Reviewer Award (IEEE Transaction Antennas and Propagation) for eight consecutive years between 2014 and 2021. He also received the Outstanding Associate Editor Award from the IEEE Antennas Wireless and Propagation Letters in July 2018. Prof. Sim has recently been appointed as the Distinguished Lecturer of the IEEE AP-Society, serving from 2024 to 2026.

The history of laptop computers began with IBM's first portable computer, the IBM 5100, introduced in 1975. Wireless internet connections and antenna designs for laptops were nonexistent until the release of the 802.11 protocol in 1997, which provided up to 2 Mbit/s link speeds. The 802.11b standard, introduced in 1999, allowed laptop connections on the 2.4 GHz band with speeds up to 11 Mbit/s [1]. Early laptops required an additional PCMCIA card for wireless connectivity, typically using monopole antennas with dual polarization [2]. Between 1999 and 2000, companies like IBM (ThinkPad T20 series) [3] and Apple (iBook) [4] introduced laptops with integrated WLAN antennas. This innovation led to more frequent appearances of WLAN antenna designs in the literature. In 2003, the 802.11g standard was introduced, offering speeds up to 54 Mbit/s using the 2.4 GHz frequency band [5]. The 802.11n standard, known as Wi-Fi 4, was released in 2007 and became widespread by 2009. It operated on both 2.4 GHz and 5 GHz bands, utilizing MIMO technology to achieve data rates up to 600 Mbit/s [6]. Consequently, from 2001 to 2007, many dual-band antenna designs for WLAN 2.4/5 GHz bands in laptops appeared in the literature [7, 8]. In 2013, the 802.11ac standard, also known as Wi-Fi 5, was introduced, exclusively using the 5 GHz band and enhancing speeds through wider channel bandwidths of up to 160 MHz, supporting speeds up to several gigabits per second. From 2013 to 2019, antenna designs focused more on tablet computers with metallic frames rather than conventional laptop designs [9, 10].

In 2019, the advent of 802.11ax, commonly referred to as Wi-Fi 6, improved on previous standards by increasing efficiency and capacity. Wi-Fi 6 operates on both 2.4 GHz and 5 GHz bands, offering speeds up to 9.6 Gbit/s. In 2020, Ofcom and the FCC announced the opening of the 6 GHz band for unlicensed use to provide additional spectrum for increased bandwidth and reduced congestion. Consequently, the Wi-Fi Alliance extended Wi-Fi 6 into the 6 GHz band, making it usable for 802.11ax as well, now known as Wi-Fi 6E. At this time, many laptop antenna designs covering the entire Wi-Fi 6E spectrum—2.4 GHz (2400-2480 MHz), 5 GHz (5150-5925 MHz), and 6 GHz (5925-7125 MHz)—were reported [11, 12]. In 2021, Wi-Fi 7, also known as IEEE 802.11be, was first discussed and announced. It is expected to utilize techniques such as 320 MHz channel bandwidth and 4K-QAM, with speeds up to 30 Gbit/s, making it suitable for advanced applications such as augmented reality, virtual reality, and ultra-high-definition video streaming. As 2024 marks 25 years of Wi-Fi and the official release of Wi-Fi 7, this Keynote Talk will focus on the evolution of laptop antenna designs over this fascinating quarter century.

References
[1] [On-line] https://www.digitaldreamsjaipur.com/the-rise-of-laptops-1975-2020/
[2] Shyh-Tirng Fang, A novel polarization diversity antenna for WLAN applications, in IEEE Antennas Propag. Soc. Int. Symp. Dig., pp. 282-285, 2000.
[3] [On-Line] https://en.wikipedia.org/wiki/IBM_ThinkPad_T20_series
[4] [On-Line] https://en.wikipedia.org/wiki/IBook
[5] C.M. Su and K.L. Wong, “Narrow flat-plate antenna for 2.4 GHz operation,” Electronics Letts, 39, 4, February 2003, pp. 344-345.
[6] [On-line] https://www.draytek.co.uk/information/blog/blog-wifi-history
[7] Y. L. Kuo, T. W. Chiou, and K. L. Wong, “A novel dual-band printed inverted-F antenna,” Microwave and Opt Technol Letts, 31, 5, December 2001, pp. 353-355.
[8] C. M. Su, W. S. Chen, Y. T. Cheng, and K. L. Wong, “Shorted T-shaped monopole antenna for 2.4/5 GHz WLAN operation,” Microw. Opt. Technol. Lett., 41, May 2004, pp. 202-203.
[9] K. L. Wong and C. Y. Tsai, “Low-profile dual-wideband inverted-T open slot antenna for the LTE/WWAN tablet computer with a metallic frame,” IEEE Trans. Antennas Propag., 63, 7, July 2015, pp. 2879-2886.
[10] C. Y. Tsai and K. L. Wong, “Half-loop frame antenna for the LTE metal-casing tablet device,” IEEE Trans. Antennas Propag., 65, 1, January 2017, pp. 71-81.
[11] S. W. Su and C. C. Wan, “Asymmetrical, self-isolated laptop antenna in the 2.4/5/6 GHz Wi-Fi 6E Bands,” in Proc. Int. Symp. Antennas Propag., Taipei, Taiwan, pp. 1-2, 2021.
[12] C. Y. D. Sim, et.al. “Low profile laptop antenna design for Wi-Fi 6E band,” IEEE Antennas Wireless Propag. Lett., 22, 1, Jan. 2023. pp. 79-83

Ying Liu received the M.S. and Ph.D. degrees in Electromagnetics from Xidian University, Xi’an, China, in 2001 and 2004 respectively. From 2006 to 2007, she carried on postdoctoral research in Hanyang University in Seoul Korea. She is currently full Professor in the School of Electronic Engineering, Xidian University. She is the author of two books Prediction and Reduction of Antenna Radar Cross Section (Xi’an: Xidian University Press, 2010), and Antennas for Mobile Communication Systems (Beijing: Electronics Industry Press, 2011). She Has authored or coauthored over 200 peer-reviewed journal articles. Her current research interests include low-RCS antennas, base-station and terminal antennas, characteristic modes and multi-mode technology, and metasurface.
Dr. Liu received the 17th China Young Women Scientist Award in 2021 and the 17th China Youth Science and Technology Award in 2022. She received the Award for Science and Technology Achievement (First Class) from Guangdong Province Government in 2017, the Award of Natural Science Achievement (First Class) from the Shaanxi Province Government in 2021, the Award of Science and Technology Achievement (First Class) from Chinese Institute of Communication in 2023. She is also a Fellow of IET (Institution of Engineering and Technology), CIE (Chinese Institute of Electronics), and CIC (China Institute of Communications), and a Senior Member of IEEE. She served as General Chair for International Applied Computational Electromagnetics Society Symposium in 2024, the TPC Co-Chair for IEEE International Symposium on Antennas and Propagation in 2019, the TPC Co-Chair for IEEE Asia-Pacific Conference on Antenna and Propagation in 2020, and the Publicity-Publication Chair for IEEE Asia-Pacific Conference on Antenna and Propagation in 2017. She is currently the chair of IEEE AP-S Xi’an Chapter, an Associate Editor of IEEE Antennas and Wireless Propagation Letters, a member of IEEE AP-S Distinguished Lecturer Program Committee, and a member of IEEE AP-S Technical Committee on Antenna Measurement.

Dr. Tadashi Takano was born in Tsukuba, Japan in 1945. He received B. S., M. S., and Ph. D. degrees in Electric and Electronic Engineering from the University of Tokyo, Tokyo, in 1967, 1969, and 1972, respectively.

In 1972, he joined the Electrical Communication Laboratories of NTT P. C. In 1984, he moved to the Institute of Space and Astronautical Science (ISAS), Japan, where he was Professor in Radio Tracking. In 1991 he became Professor in Electronic Engineering in the Graduate School of the University of Tokyo. In 2008, He moved to Nihon University, as Professor, and retired in 2014 to be now a Fellow Researcher in the same university. He is the author of three books, more than 150 articles, and more than 70 inventions. His research interest includes antenna engineering, radio wave applications to space debris monitoring and natural hazard detection, wireless power transfer, and space commercial utilization

Dr. Takano is a member of IEEE (Fellow), IEICE (Fellow), Institute of Electrical Engineers of Japan, URSI, Japan Society for Aeronautical and Space Science, Japan Rocket Society, Space Solar Power Systems Society (Director), Society for the Space Travel of Japan (Chairman of the Board), and Japan Space Elevator Association (Adviser) . He received the 1975 Yonezawa Award and the 1992 Excellent Paper Award both from the Institute of Electronics, Information and Communication Engineers (IEICE) of Japan, the 1983 Kajii Award from NTT, the 1998 Prize of Japan Society for the Promotion of Machine Industry, and iWAT2010 Best Paper Prize.

Yuichi Kimura received a B.S., M.S., and D.E. in electrical and electronic engineering from Tokyo Institute of Technology, Tokyo, Japan in 1996, 1998 and 2001, respectively. He was a Research Associate from 2001 to 2006 and is currently an Associate Professor at the Graduate School of Science and Engineering, Saitama University. His research interests include microstrip antennas and slotted waveguide array antennas. He received an IEEE AP-S Japan Chapter Young Engineer Award in 2006. He is a Member of IEICE and IEEE.

Multi-band and wideband planar antennas have been strongly demanded for various wireless applications. Microstrip antennas (MSAs) are widely used as practical planar antennas because of their attractive advantages of small size, low profile, light weight, and low manufacturing cost. The authors have developed multi-ring microstrip antennas (MR-MSAs) as multiband planar antennas. The MR-MSA consists of multiple ring patches arranged concentrically and an L-shaped feeding probe (L-probe) with a double-layered dielectric substrate. The MR-MSAs exhibit flexible multiband design capability because the resonant frequencies can be controlled flexibly and because stable unidirectional radiation patterns can be preserved against the frequencies. Furthermore, linear and circular polarizations can be also designed individually at the resonant frequencies. The MR-MSAs fed by an L-probe with a single-layered dielectric substrate have been also developed as linearly-polarized multiband planar antennas.

Another challenge of the MR-MSAs fed by an L-probe is wideband design. When a thin dielectric substrate is used for the MR-MSAs, bandwidths of the MR-MSA become narrow. The authors have developed single- and dual-band MR-MSAs fed by an L-probe with a thick dielectric substrate for wideband operation. The single-band and wideband ring MSA provides more than 40% fractional reflection bandwidth below –10 dB reflection, where a thick double-layered dielectric substrate with a thickness of approximately 0.15 wavelengths at the center frequency is used. The dual-band and wideband MR-MSA with a thick triple-layered substrate offer 20.3% and 15.7% fractional bandwidths. Furthermore, linearly dual-polarized and wideband MSAs fed by two L-probes arranged orthogonally with a multi-layered or single-layered substrate. have been proposed. In this talk, design examples of multiband and wideband MR-MSAs fed by an L-probe are presented.