Tutorial 1: RF energy harvesting system
Energy harvesting, also known as energy scavenging, is a method that converts surrounding ambient energy into useful DC power for low power devices. RF energy harvesting system is demanding research area of interest in recent times. A RF energy harvester consists of a receiving antenna, matching, and rectifying circuits. Receiving antenna works to receive RF waves/energy from the surrounding and a rectifying circuit converts the EM waves into a DC power. The RF energy harvesting antennas are instigated in the receiver side to receive the EM waves from the various ambient RF sources, which are broadly available such as digital TV broadcasting (500-MHz band), mobile phone services (UHF-band down link), and several other wireless systems. Research on RF energy harvesting is going on in several areas such as low power wireless sensors, RFID (radio frequency identification) tags, IoTs, and biotelemetry. With the advances and popularity of wireless communication devices, large amount of abundant RF energy from surrounding sources are scattered in our environment. Using an appropriate antenna, these EM waves can be converted into electrical energy. Linearly polarized antenna receives only noise signals when the receiving antenna is not aligned with the transmitting antenna. The ambient EM waves exist in all sorts of orientation and polarization, thus high performance circularly polarized antennas or dual-polarized antennas are preferred for RF energy harvesting applications. A circularly polarized antenna is insensitive to the multi-path effects and is able to harness RF energy regardless of the device’s orientation. For energy harvesting systems, a circularly polarized antenna connected to rectifier circuit is expected to convert RF to dc power independent of source polarization. Different type of antenna and rectenna structures will be discussed in details for RF energy harvesting applications. An overview of the antennas for RF energy harvesting will be covered and the specifications for these antennas such as low profile, wideband, high gain, widebeam, lightweight, compact size, polarization, multiband, planar/conformal structure, etc.
About the speaker:
Dr Nasimuddin received his B.Sc. degree in 1994, from Jamia Millia Islamia, New Delhi, India, and his M.Tech. (Microwave Electronics) and Ph.D. degrees in 1998 and 2004, respectively, from the University of Delhi, India. Dr Nasimuddin has worked as a Senior Research Fellow (1999-2003) in DST sponsored project on “Optical Control of Passive Microwave Devices” and Council of Scientific and Industrial Research (CSIR), Government of India, Senior Research Fellowship in Engineering Science for the project entitled “Investigations of microstrip antennas as a sensor for determination of complex dielectric constant of materials” at Department of Electronic Science, University of Delhi, India. He has worked as an Australian Postdoctoral Research Fellow (2004-2006) in awarded Discovery project grant from Australian Research Council for project entitled “Microwave sensor based on multilayered microstrip patch/line resonators” at the Macquarie University, Australia. Currently, he is a scientist at the Institute for Infocomm Research, A-STAR, Singapore. He has published 201 technical papers in journals/conferences and granted/filed four US patents with several antenna technologies licensed to companies on microstrip-based microwave antennas and components. He has edited two books (“Microstrip antennas” and Elements of Radio Frequency Energy Harvesting and Wireless Power Transfer Systems) and contributed two book chapters. His research interests include multilayered microstrip-based structures, millimeter-wave antennas, radio-frequency identification reader antennas, Global Positioning System/Global Navigation Satellite System, ultra-wideband antennas, metamaterials-based microstrip antennas, beamforming/beam-steering antennas, satellite antennas, RF energy harvesting systems, circularly polarized microstrip antennas, and small antennas for TV white space communications.
He is a Senior Member of the IEEE/IEEE APS and Chair/executive committee member of IEEE MTT/AP chapter/CRFID chapter Singapore. He has been organizing committee member of international/national conferences related to antenna and propagation. He was awarded a senior research fellowship from the Council of Scientific and Industrial Research, Government of India in Engineering Science (2001-2003); a Discovery Projects fellowship from the Australian Research Council (2004-2006); Singapore Manufacturing Federation Award (with project team) in 2014, the Young Scientist Award from the International Union of Radio Science (URSI) in 2005, and Exceptional performance reviewer award certificate in 2019 (IEEE Trans. Antennas and Propagation).
Tutorial 2: Inter-antenna interaction and its effects in MIMO wireless
It is a well-established fact that Multiple-input-multiple-output (MIMO) wireless is already employed in 5G wireless and it is a technology expected to be used in beyond 5G and 6G wireless. The main advantages of the MIMO wireless in comparison to the conventional Single-input single-output (SISO) wireless are its two major gains viz. diversity gain (DG) and multiplexing gain (MG). The MG can be derived from the channel capacity of the MIMO system. But due to utilization of multiple antennas at the transmitter and receiver, the problem of interantenna.
Interaction (IAI) is inevitable in the MIMO wireless. The two most important IAI parameters for MIMO antennas are envelope correlation coefficient (ECC) and antenna correlation coefficient (ACC). The ECC can be accurately calculated from the 3-D radiation patterns of the MIMO antenna. From the ECC, ACC can be obtained. Once ACC matrix of the MIMO antenna is available, it can be used to observe the effect of MIMO antenna on the MIMO system’s performance such as the DG and the MG. It can be also utilized for the calculating the channel capacity loss (CCL). The CCL for single-user MIMO (SU-MIMO) and multi-user MIMO (MU-MIMO) will be calculated and investigated for some typical point-to-point MIMO and distributed MIMO systems respectively. It has been apparent that the ECC for MIMO antenna is the most important IAI parameter which decide the performance of the MIMO antenna in the MIMO systems. So the aim and objective of MIMO antenna engineers should be minimizing the ECC. In wireless domain, IAI has been completely eradicated by techniques such as Spatial modulation. A brief discussion on such techniques will be initiated. Several MIMO antenna examples will be provided which minimize mutual coupling and the ECC to a great extent and study their effect on the MG and the DG will be carried out.
A brief discussion on the evolution of the MIMO systems, from SU-MIMO to MU-MIMO, MU-MIMO to massive MIMO (mMIMO), mMIMO to cell-free massive MIMO (CF-mMIMO) will be pursued in this talk.
About the speaker:
Rakhesh Singh Kshetrimayum (Senior Member, IEEE) received the Ph.D. degree from the School of Electrical and Electronics Engineering (EEE), Nanyang Technological University, Singapore in 2005 and the B.Tech. degree in Electrical Engineering (EE) from the Indian Institute of Technology (IIT), Bombay, India in 2000. Since 2005, he has been a faculty member with the Department of EEE, IIT Guwahati, presently working as a Professor and was the former Head of Centre for Career Development from 2018 to 2020. He did postdoctoral research at the Department of EE, Pennsylvania State University, USA, in 2005 and the Department of Electrical Communication Engineering, Indian Institute of Science, Bangalore, from 2004 to 2005. From 2000 to 2001, he worked as a Software Engineer with the Mphasis, Pune. His current research interests are in the areas of antennas, RF circuit designs and performance analysis for beyond 5G technologies. He has authored or co-authored four books and more than 130 papers in international journals and conference proceedings.
Dr. Kshetrimayum is an Editor of the IEEE COMMUNICATIONS LETTERS and an Associate Editor of the IEEE OPEN JOURNAL OF ANTENNAS AND PROPAGATION. He has also served on the editorial board of the IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES and on the program committees of several international conferences including IEEE GLOBECOM, IEEE ICC, and APMC. He has received multiple Best Paper Awards such as IEEE ANTS 2017 Best Paper Award (Third Prize). He is a Fellow of the IET (UK) and a Member of Sigma Xi (USA).
Tutorial 3: Electromagnetic and Microwave Applications of Superconducting Devices
This tutorial aims at familiarizing electrical engineers with the electromagnetic properties and models of superconducting materials and devices at microwave frequencies. The simple electrical models and working principles of superconducting devices, e.g., Josephson junction (JJ) and superconducting quantum interference devices (SQUIDs), are presented without delving the audience into detailed quantum mechanics. Instead, we try to get along using Maxwell’s equations, circuit theory, hands-on examples with Spice® and Simulink®.
Since the invention of JJ and SQUID, their applications in scientific instrumentations, microwave and millimeter-wave electronics, biomedical systems (e.g., MRI), and high-speed processors are incessantly on the rise. Examples include scientific instrumentations, astronomical detectors, compact microwave filters for satellite and mobile communications, digital multi-GHz processors using Josephson Junctions (RSFQ gates) as well as quantum bits (qubits). The advent of high-temperature superconductors (HTS) and more compact and affordable cryogenic techniques have also made these materials’ applications in power engineering systems more beneficial than early days.
The trends mentioned above promise job opportunities for electrical engineers who can design, analyze and work with superconductive circuits and devices. And in this tutorial, I try to convey some of the skills and know-how’s to electrical engineers who do not have the ime to delve into hefty tomes on BCS and Ginzburg-Landau’s theory of superconductivity.
About the speaker:
Daryoush Shiri received his Ph.D. degree in electrical and computer engineering in 2013 from the University of Waterloo, Canada. Prior to this, he worked in Kuala Lumpur, Malaysia, as a radio-frequency/analog CMOS design engineer and team leader. His thesis was devoted to the computational study of electron transport in silicon nanowires which led to proposing lasing in silicon nanowires. As a postdoctoral fellow at the Institute for Quantum Computing, Waterloo (2013–2015), he collaborated in developing a scalable package for quantum-computing circuits. He came to Sweden in 2016 as a postdoctoral fellow at the Department of Physics, Chalmers University of Technology, to work on heat transport in 2D materials. Among his research contributions are Gunn effect in silicon nanowires, heat-to-mechanical energy conversion and voltage-controlled heat-diode in graphene. Currently, he is a researcher at Quantum Technology Laboratory in the same university, working on the electromagnetic simulation of superconducting circuits for quantum computing. He co-supervised several Ph.D. and master’s degree students during these years. He loves teaching and always quotes John Archibald Wheeler: “If you would learn, teach.” In his free time, he enjoys cycling, cooking, translating, and reading historical/comparative linguistics. He is a Member of IEEE, APS, and German Physical Society.