Using a novel broadband microchamber, electrical detection of live and dead single cells was demonstrated. Tests on Jurkat cells showed that live cells had lower resistance but higher capacitance than that of dead cells. The test results were compared with the limited literature on broadband electrical detection of single cells and the discrepancies, both qualitative and quantitative, were discussed. These results indicate that, while broadband electrical detection at the single-cell level is becoming feasible, many challenges remain in impedance match, calibration, sensitivity, cell manipulation, solution effect and modeling.

1. Introduction (Power/Signal Integrity & EMI design)
2. Conventional Simulation Techniques (SPICE or FDTD-based techniques)
3. Advanced Simulation Techniques (Leapfrog technique and derivatives)
4. Numerical Examples in the PI/SI/EMI Issues (Full wave/ many core simulations)

In this seminar, I will present the recent advances on metamaterials conducted at Southeast University in China in three perspectives: microwave metamaterial lenses, transformation electrostatics, and plasmonic metamaterials.
In the first part, I will introduce several types of microwave lenses which are composed of homogeneous or inhomogeneous metamaterials based on different physics principles, including super-resolution imaging lenses, polarization convention lenses, and high-gain lens antennas.
Transformation electrostatics is a d.c. reduction of the transformation optics, which provides a freedom way to control the electric currents and potentials. Transformation optics has been used to design and create a lot of novel devices theoretically and numerically, but few of them have been realized due to the difficulties in fabrications of inhomogeneous and anisotropic permittivity and permeability. However, transformation electrostatics provides us an efficient methodology to design and realize novel d.c. devices freely. Using the analogy between electrically conducting materials and resistor networks, such d.c. devices can be designed using the circuit theory. In the second part, I will introduce a series of transformation electrostatics devices.
Finally, I introduce a kind of planar plasmonic metamaterial on thin metal films with nearly zero thickness. For the theoretical simulations and experiments, we show that spoof SPPs can propagate along a thin metal film by corrugating its edge with periodic array of grooves. Such a planar plasmonic metamaterial can sustain highly localized SPPs along two orthogonal directions in the terahertz and microwave regions in broadband by keeping good modal shape and propagating long distance with low bending loss. The ability to bend spoof SPPs freely on thin film makes the planar plasmonic metamaterial more practical to produce plasmonic devices. Based on the above idea, we also present the concept of conformal surface plasmons (CSPs), i.e., the surface plasmon waves that can propagate on ultrathin and flexible films to long distances. The flexible ultrathin films can be bent, folded, and even twisted to mould the flow of CSPs.

Additive manufacturing technologies, often called 3D printing, have received much attention recently with impressive demonstrations ranging from musical instruments, to vehicles, to housing components or even entire buildings. Different structural materials including metal, polymer, ceramics, biological tissues and even concrete, have been incorporated in various 3D printing technologies. Printing dimension ranging from nanometers to meters has been reported. This presentation will highlight several research projects being carried out at Prof. Hao Xin’s group in the area of 3D printed electronics such as waveguides, antennas, lenses and holographic devices for GHz to THz operation. Interesting applications enabled by 3D printed structures such as a new type of lens array for electronic beam scanning will also be described. Some of important future research directions will be discussed as well.

The presentation focuses on the development of wireless medical micro devices for endoluminal applications. The technology platform is based on wireless energy transfer for batteryless implants, miniature electrochemical and MEMS sensors, and wireless communication. Batteryless endoluminal sensing telemeter architectures will be discussed including esophagus and stomach sensor implants and a wireless bladder volume monitoring implant for urinary incontinence management. The talk will discuss wireless power transfer that enables long-term gastrostimulation applications. These miniature batteryless devices can help to empower patients in managing their own health and assisting better quality of life.

This talk introduces inkjet printing as an emerging new technique to realize low cost, flexible and large volume systems in the field of Radio Frequency (RF) electronics. Inkjet printing is being used for printing texts and graphics since decades, but has recently found application in electronics. Though the major focus of printed electronics has been in photovoltaic cells and flexible displays, recently applications such as RFIDs, wireless sensors and wearable electronics have also received a lot of attention.  The recent interest in inkjet printed RF electronics is due to the latest developments in nano-particles based conductive inks which can achieve conductivities close to that of bulk metals.  This has opened doors to print passive components such as antennas, inductors, transmission lines, etc on low cost and flexible substrates such as plastics and papers. The talk will present many inkjet printed designs on paper substrate for a variety of applications, such as wireless sensing and tracking. In addition to conductive inks, this talk will also discuss dielectric and semiconducting inks to realize all inkjet printed multilayer RF components. The promising results of these designs indicate that the day when electronics can be printed like newspapers and magazines through roll-to-roll and reel-to-reel printing is not far away.

Body-centric wireless communications refer to human-self and human-to-human networking with the use of wearable and implantable wireless sensors. It is a subject area combining wireless body-area networks (WBANs), Wireless Sensor Networks (WSNs) and Wireless Personal Area Networks (WPANs). Body-centric wireless communications has abundant applications in personal healthcare, smart home, personal entertainment and identification systems, space exploration and military.
This talk presents a review of some current work conducted at Queen Mary University of London, related to antennas and propagation for body-centric wireless communications. Aspects related to measurement setup, numerical modelling, channel characteristics are briefly discussed. Applications and future trend of this research will be also presented.

The terahertz band (0.3 -10 THz) is associated with several attractive applications, including spectroscopic identification, security, non-destructive imaging and wideband proximity wireless communications. However, exploitation of the terahertz band is still at its infancy. This is due to the lack of portable sources, transceivers and low cost portable imaging devices. Recently, Ohio State acquired several sub-terahertz and terahertz equipment for signal generation, spectroscopy, imaging, testing and evaluation of components and systems. In this presentation, we will review several new developments in terahertz as relates to sources, communications, and imaging. Unique equipment set-ups will be presented along with demonstrations that exploit the potential of terahertz for near-zone communications, imaging and security.

Recent breakthroughs in the theory of Transformation Electromagnetics, such as the possibilities concerning cloaking and invisibility, have caught both the scientific and popular imagination, and have stimulated a huge growth in related research around the world. The potential of the underlying Transformation Electromagnetics approaches however have much wider applicability than cloaking alone, in arguably more important applications that span communications, energy transfer, sensors and security. However, theory and concepts are outstripping practical demonstration and testing, leading to a mismatch in what may be theorised and computed and what can be realised for impact in society and commerce. In this talk, Prof. Hao will review the history of research on transformation electromagnetics and metamaterials for achieving the invisibility. He will demonstrate potentials and physical limitations of metamaterials through numerical simulations and microwave experiments. The roadmap for developing radically novel devices based on transformation electromagnetics and metamaterials engaging UK leading theorists, modellers and material scientists will be discussed.

Microwave Doppler radar is capable of detecting human heartbeat and respiration or mechanical vibrations from a distance away. This noncontact detection method has many potential applications In healthcare, veterinary medicine, biology, industrial manufacturing, etc. Through understanding of its detection mechanism and advances in hardware and software, the once bulky Doppler radar systems can be miniaturized while achieving the same or even better performance. In this seminar, I will introduce several integrated radar sensors demonstrated by my research group in University of Florida. These micro--‐radars, whether integrated in PCB modules, CMOS chips, or System-in-Package (SiP), and whether they are operating at 5.8 GHz or 60 GHz band, enable small portable systems that can be conveniently carried around to measure vital signs and vibrations for many different applications. The small integrated radar sensors can potentially be used in wireless sensor network for pervasive healthcare monitoring.

The social impact of innovations in electronics is undisputed. From hundreds of megahertz to millimeter-wave frequencies, the evolution of wireless has brought convenience into our day-to-day lives in the form of communication through smart phones, navigation by GPS, information sharing through wireless sensor networks and safety by automotive radars. The next in the line are intelligent, wearable, sensing and wireless communication devices. The demand for sensing and accessing information everywhere and all the time is driving the innovation in miniaturized, light-weight and low cost wireless technologies. The focus of this talk is to demonstrate miniaturization possible through highly integrated systems at the chip (system-on-chip “SoC”) as well as package (system-on-package “SoP”) levels for power efficient sensing and wireless communication applications. Representative designs in technologies such as standard CMOS, 3D LTCC packaging and inkjet-printing on paper will be presented.

Dr. S. Sendhil Velan, Laboratory of Molecular Imaging, Singapore Bioimaging Consortium, A*STAR, Singapore

28 November 2013, 1530-1730 hrs @ Franklin Seminar Room (Fusionopolis, 11th floor, Connexis South Tower), Institute for Infocomm Research

Magnetic resonance imaging (MRI) and Magnetic Resonance Spectroscopy is currently used widely in both pre‐clinical and clinical settings. This technology is based on a wide variety of physical parameters, which, in principle, can influence the image contrast, resolution, signal to noise, and contrast to noise. The MR technology is continuously evolving in terms of hardware and new generation of pulse sequences for achieving quantitative information in human and animal models. In this seminar I will cover the fundamentals of both imaging and spectroscopic hardware and physics.

In this talk, we will first discuss new challenges in small antenna design for high speed data transfer (gigabit rate) and energy harvesting, both of which topics have been receiving considerable attention recently. Next, we will describe a new domain decomposition technique for analyzing MMIC circuits, useful for rapid prototyping of electronic packages, and reducing the time-to-market as well as the cost.

In the era of information communication technology (ICT), RFID has been going through tremendous development. RFID market surpassed $7.6 bn in 2012. RFID technology has the potential of replacing barcodes due to its large information carrying capacity, flexibility in operations and versatilities in applications. However, the penetration of RFID technology is hindered due to its high price tag. Many projects had been stalled only due to the cost of the tag. The application specific integrated circuits (ASICs) in RFID tags are the most expensive item. Fully printable chipless tags will provide competitive advantages over barcodes. If chipless RFID can be made less than a cent, the chipless RFID market will surpass $4 bn by 2019.
With unique features of identification, tracing and tracking capabilities, RFID also gives value added services incorporating various sensors for real-time monitoring of assets, public installations and people from various backgrounds. Chipless RFID sensors for temperature, relative humidity, pH, impact and presence of noxious gas monitoring have opened new prospects.
Since the chipless tag has no intelligence, the signal processing is done only in the reader. Therefore, a full new set of requirements and challenges is needed to be incorporated and addressed, respectively, in the chipless RFID tag reader. This seminar addresses the development made in new chipless RFID tags and sensors, reader architecture and signal processing techniques at Monash University.

Radar is a technology that is over 100 years old ‐ the first example of what we would now call a radar was actually demonstrated and patented by a German inventor, Christian H¨¹lsmeyer, in 1904, though it was not a commercial success. Nowadays radar is used for a wide range of purposes, including Air Traffic Control (ATC), marine navigation, geophysical monitoring of Earth resources from space, automotive safety, weather tracking, as well as numerous applications in defense and security.
Bistatic radar, in which the transmitter and receiver are at separate locations rather than being co-located, has a history almost as long as radar itself. Not surprisingly, the separation of transmitter and receiver introduces some complications, but there are some advantages as well. A quotation from the philosopher George Santayana reads: 'Those who cannot learn from history are doomed to repeat it'. And that is just as true in engineering, not only in understanding just how things were conceived and made to work, but also in understanding ideas from the part which maybe didn't work, but only because the technology was not then available. The lecture will look at some historical developments of bistatic radar-some of which have only just come to light - and to show how they can help guide our thinking in present‐day radar engineering.

The researchers from Tongji University have long been working on research of metamaterials. The latest progress in the microwave metamaterials research at Tongji University will be introduced. In particular, the study of microwave metamaterials in time-domain will be discussed in details. The energy transportation in metamaterials and some of potential applications of metamaterials at microwave will be reported as well.

The Fabry-Perot (FP) resonator was originally found in optical research. It was named after two French physicists, Alfred Perot and Charles Fabry, who developed the classical FP interferometer at the beginning of the 20th century. The principle of FP resonator is based on multiple reflections of waves between two closely spaced reflective mirrors. Today, applications of FP resonator have been extended to submillimeter-wave, millimeter-wave, and even microwave frequencies. In recent years, significant attention has been paid on applying FP cavities for designs of high-gain millimeter-wave antennas. Conventionally, the objective of using the FP resonator is to focus the energy and, thus, enhance the antenna gain. In other words, the FP resonator has been used as a focusing element. Using this method, high antenna gains of ~20dBi or more were obtained. Practically, whether or not a high-gain antenna is needed depends on the actual application and propagation environment. For example, a highly directive antennas will be needed if a long transmission distance or suppression of multipath problems is required. But for mobile communications, a broad-beam or low-gain antenna will be more desirable even at millimeter-wave frequencies. In this seminar, antennas using the FP resonator as a non-focusing element are presented. The antenna is called Fabry-Perot resonator antenna (FPRA). Although there are other kinds of resonant-type antennas (e.g., microstrip antennas and dielectric resonator antennas), their physical sizes when operating in low-order modes may be too small to fabricate precisely at millimeter-wave frequencies. In contrast, since the FPRA is an open resonator, it is relatively easier to fabricate it in the millimeter-wave band. Both the basic and differential FPRAs will be covered in this seminar.

In this talk, a novel measurement method for adaptive interference suppression in in-situ radiated emission test will be presented. The first step of the method is to obtain multi-channel data for directions of arrival (DOA) estimation of the signals from equipment under test (EUT) and ambient interference sources by using such spatial spectrum estimation technique as multiple signal classification algorithm (MUSIC). Then, broadband minimum variance distortionless response (MVDR) beamforming algorithm combined with short time Fourier transform (STFT) was taken to form the beam pattern null traps in the directions of interferences, thus realizing the suppression on interferences. The factors affecting the accuracy of DOA estimation and the angular resolution of beamforming will be discussed and the suppression effects on different kinds of interferences will be presented. The experimental evaluation results will also be presented with analysis of the performance. The results show that single tone and pulse modulation interferences can both be suppressed considerably.

Computational electromagnetics (CEM) research is important for producing simulation softwares that have been used for virtual prototyping and the design of major electrical and electronic components. Solving electromagnetics problem is a challenging task, especially when the structure is electrically large and involves multi-scale structures. This kind of structures is often encountered in circuits in electronic packaging, small antenna designs, RFID sensor designs, and antennas on complex platforms.
In this presentation, we will give a brief introduction to the physics of electromagnetic fields. Then we will give an overview of past and recent progress in large scale computing in electromagnetics by our research group, and by other groups around the world. We will discuss various methods to overcome multi-scale problems such as some domain decomposition method using equivalence principle algorithm (EPA), and some difficulties associated with it. Various methods to stabilize and improve the accuracy of numerical methods will be discussed. We will propose some high-frequency techniques when ray-physics becomes important.

Even though Maxwell’s equations have been completed in 1864, which is close to 150 years ago, their enormous impact on various areas of science, and many forms of technologies is undisputable. Despite its age, electromagnetic theory has inspired other modern fields such as Yang-Mills theory which is intimately related to geometry, and quantum electrodynamics, which is the quantum version of electromagnetic theory. Hence, opportunity arises to marry classical electromagnetics with modern physics and mathematics in order to inject new life in this discipline. Without doubt, this marriage will be an active area of research for future science and technology development. This talk will give a brief introduction on the historical development of electromagnetics comparing the development between optics and electromagnetics. Then the three physical regimes of electromagnetics: circuit physics, wave physics, and ray physics, will be discussed. Often mathematical finesse and physical insight are needed to solve electromagnetic problems. Closed form solutions were derived many years ago, inspired by knowledge inherited from fluids and acoustics. In addition, in the early days, approximate methods were used to solve many problems. Review of some of these methods will be given. Then we will talk about computation methods and fast algorithms for solving highly complex problems, as well as inverse problems. Due to advances in nano-fabrication technologies, sub-optical wavelength structures are routinely made. This gives rise to the field of nano-optics where computational electromagnetics is becoming increasingly important. The relation of electromagnetics to geometry will be discussed, as well as recent development in quantum electromagnetics.

Plasmonic and metamaterials have introduced tremendous research interest within last decade and has become an increasingly important field in nanophotonics. The extraordinary optical properties of plasmonic structures and metamaterials have opened up a variety of novel applications such as super resolution imaging, deep-subwavelength waveguides, ultrasensitive sensors and etc. In this talk I will review some of our recent work on active and passive control of light by using plasmonics and metamaterials. Plasmonic structure illumination microscopy, combining structured illumination technique and surface plasmon interference, represents a unique approach for high speed super resolution optical imaging. Our most recent experimental results will be presented with resolution improvement factor ~3 compared to that of conventional microscope. Metalens, comprising metal-insulator-metal waveguides, are designed to perform super resolution focusing and Fourier transform. Such lens can also act as “Janus lens” to break the forward backward imaging symmetry and the detailed imaging characteristics will be discussed. An integrated plasmonic OLED structure will also be introduced for super contrast biomedical imaging. Other topics such as plasmonic enhanced high efficiency high speed LEDs, dispersion engineering in compound lenses, and super resolution optical lithography will also be briefly discussed.

Transformation optics as a tool has generated much interest in recent years. It offers revolutionary ways to manipulate light (from radio frequencies to the visible) and also other forms of electromagnetic waves, such as the surface plasmons. Among the plethora of its applications, it is perhaps the demonstration of invisibility cloak that has sparked the greatest excitement. Other novel applications of Transformation optics, involves the direct manipulation of EM waves, and these include the flatten Luneburg lens, super-scatterers, field rotators, just to name a few. The application of Transformation optics in plasmonics has also generated new developments, such as surface plasmon guiding and focusing. The possibility of manipulating surface plasmons has open up more alternative means of information transfer beyond the traditional electron transport, promising much faster data transfer rates. The ability to focus surface plasmons can also vastly improve the sensitivities of chemical detectors and enhance the efficiencies of photovoltaic devices. Indeed, this new strategy of manipulating light has posed fascinating possibilities and challenges for experimentalists and theorists, driving forward new techniques and conceptual approaches to old problems. In this talk, I will talk about the progress in the study of transformation optics, and the resolution to the challenges of realizing these ideas. The focus of the talk would be on how to simplify the required material parameters while optimizing the performance of Transformation optics devices. Specifically, I will highlight a special sub-class of transformations, i.e. linear transformations, which enables devices to be more easily implemented using natural birefringent crystals or homogeneous grating structures. As examples, I will show how to design macroscopic invisibility cloak at optical frequencies, full-parameter omni-directional cloak, broadband SPP bending structures, and abrupt SPP focusing, using these linear transformations.

Metallic nanoparticles that support localized surface plasmon resonances can concentrate light into a deep-subwavelength volume, thereby achieving very large field enhancements. Many emerging nano-photonic technologies rely on the careful control of this field enhancement, including cancer therapy, improved photovoltaic devices, and optical antennas for enhanced light-matter interactions. However, at deep subwavelength scales, classical continuum electrodynamics fails to describe the optical responses of nanoparticles owing to nonlocal screening and the spill-out of electrons. Electron correlations that are driven by these effects require a new model of nonlocal transport, which is crucial in nanoscale optoelectronics. In this talk, I will present a systematic strategy, based on transformation optics, to study analytically the plasmonic interaction at subnanometer scales. Our approach incorporates radiative, nonlocal, and quantum tunnelling effects, and thus can be applied to design realistically sized plasmonic systems. As an example, I will use this method to elucidate the optimum shape of a nanoparticle that maximizes its absorption and field enhancement capabilities.

This talk mainly focuses on how metamaterials can be used to control direction of the emission of an EM source. In the first part of this presentation, I will introduce and compare three different approaches to achieve directive emission with metamaterials, i. e. by embedding a single line source in a slab of (a) a zero-refractive-index metamaterial (b) an extremely anisotropic metamaterial (c) a transformation medium with a spatially-variant refractive-index. The emitted energy is concentrated around the surface normal of the slab, and thus a far-field directive radiation can be achieved. In the second part of my talk, I will show that a transformed current distribution with an appropriately designed metamaterial coating produces similar radiation characteristics as the original antenna. This method thus provides a possible route to achieve conformal antennas.

The 60 GHz band has been an active subject of research during the last 15 years. This is due to its unique properties: a worldwide unlicensed bandwidth, a small wavelength and a high path loss. Several standards have emerged and integrated transceivers in CMOS processes following these standards have been published. This opens the path to low cost solution for high volume market 60 GHz modules. The Antenna-in-Package is here the chosen approach. We will study it using several technologies through its conception and measurement.

Integrated Passive Devices (IPD™) technology offers an aggressive process in terms of drawing lines, on a low loss glass substrate. This process is widely used at low frequency circuits (1-10 GHz) to design baluns, filters and matching network. In this presentation, we will investigate the potential of IPD™ to deliver affordable and high performance solutions for circuits and antennas in the millimeter-wave bands. A Butler Matrix at 60 GHz will be presented. Influence of the integration schemes on the system performance will be also studied.

In this talk, I will present a 2.45 GHz wireless microphone for cochlear implant. The transmitting part of the system consists in an analog part (ramp generator and comparator) from a simple ramp ADC (Analog-to-Time converter only) as well as the RF transmission part. The digital part of the ADC is shifted to the receiver, where the signal picked-up by the antenna is amplified by an LNA and then demodulated into its OOK form by an envelope detector. The PWM signal is sent to a counter and transformed into digital for which the equivalent number of bits depends on the clock frequency of the DSP and the envelop detector performance. Especially the digital part is replaced by an analog filter in order to restore the analog signal.

In this talk, we will first present the development of a Millimeter-wave Measurement Setup and dedicated techniques to characterize the matching and radiation performance of Probe-fed Antennas. Indeed, the measurement of the radiation and matching performance of millimeter-wave antennas is a very challenging topic. As a single antenna has usually a size of few square millimeters, the feeding scheme can’t be as simple as a connector, especially if strong measurement accuracy is needed. That’s why a microelectronic probe feeding technique is a possible improvement. However, the final choice depends about the antenna technology and also the way the antenna is integrated. On-chip antennas using silicon substrates or antennas integrated into ceramics or organic packages are today the most popular solutions, the latter being the most efficient. The measurement setup we present has been developed from a classical microelectronic probe measurement set-up but has been mechanically modified to operate in almost a metal free environment, especially around the antenna-under-test (AUT). It is then possible to measure the gain of linearly and circularly-polarized radiators in several cut-planes with a ± 0.8 dB computed accuracy at 60 GHz. It is also possible to measure the radiated field over a quasi-3D sphere, the microelectronic probe being the only blocking object of the electromagnetic waves transmitted by the AUT. Therefore, several methods have been implemented to be able to compute the axial ratio, the total and radiation efficiencies from these radiation measurements. Then, several examples of Antenna-in-Package for Mm communications are presented to demonstrate the capabilities of the set-up.

28 March 2013, 1000-1130 hrs @ Franklin Seminar Room (Fusionopolis, 11th floor, Connexis South Tower), Institute for Infocomm Research

The fundamental concepts of radiometers (passive imaging) and imaging arrays (active imaging) will be covered. This includes the definition of responsivity, noise-equivalent power (NEP), Dicke switching and 1/f noise, integration time and NEDT, antenna coupling efficiency especially when using on-chip antennas, will be first presented. The talk will then cover some of the latest chips developed by academia and industry at 94-160 GHz (radiometers) and 160-800 GHz (detectors and active imaging arrays) using SiGe, CMOS and advanced CMOS SOI nodes.

A hybrid simulation algorithm judiciously combines several numerical solvers to fully exploit the accuracy of rigorous schemes and the efficiency of approximate schemes to provide viable design tools. This approach is particularly important when dealing with the electrically small and large (in terms of the wavelength of the signals) features within the same geometry/modeling space, which is often the case in the sub-mm/THz devices, systems and in a large complex Radio propagation environment.
In this Seminar we describe a hybrid EM modelling technique based on combining ray tracing method with FDTD method, which uses ray tracing to analyze wide areas and FDTD to treat areas close to complex discontinuities, where ray based solutions are not sufficiently accurate. Besides much improved accuracy, the hybrid method only applies FDTD to a small portion of the entire modeling environment, which ensures practicality in terms of computational resources.
The hybrid method also enables the study of effects of generic indoor structural features, furniture, inhomogeneity inside walls and any objects that may have significant effect on signal coverage and statistics inside buildings. Furthermore, the method provides solution to the problem of outdoor-indoor signal coupling in the presence of inhomogeneous walls by using the ray tracing - FDTD – ray tracing approach. The method makes it possible to study the effect of inhomogeneity inside walls more accurately without adding much to the computational complexity; especially when the incident waves can be approximated by plane waves and the wall structure is periodic. Examples are given to show that in the areas where the specular signal is blocked by metallic structures, the proposed method can accurately predict signal coverage by taking into account the fields scattered by the inhomogeneity inside walls while the ray tracing method is not satisfactory. The ability of the developed method to analyze fading in signal strength, Doppler spread and time dispersion caused by multipath is also demonstrated in this seminar.    

Prof. George V. Eleftheriades, Department of Electrical and Computer Engineering, University of Toronto, Canada

20 March 2013, 1530-1730 hrs @ Potential I & II (Fusionopolis, 13th floor, Connexis North Tower), Institute for Infocomm Research

In this seminar we will describe our efforts towards sub-diffraction imaging and sensing. First, the problem of sub-diffraction imaging will be introduced and then solutions in the near-field will be summarized using transmission-line metamaterial superlenses. Subsequently, we will introduce the concept of the "shifted beam theory" which enables launching sub-wavelength spots in the near-field using metascreens (arrays of non-periodic and sub-wavelength spaced antenna arrays). Several sub-wavelength focusing and imaging metascreens will be presented. This will be followed by describing the challenging problem of sub-diffraction imaging in the far-field and its potential solution using the concept of ‘super-oscillations’. First, we will demonstrate how to synthesize (in principle) arbitrarily narrow pulses in the time domain while only utilizing a given, fixed, bandwidth. Based on this ‘beyond the Fourier Transform’ approach we will show experimental results from a super-resolution radar for range detection. Subsequently, we will explain how super-oscillations can be used to establish sub-wavelength beams in space at the multi-wavelength range. We will then present microwave and optical arrangements that can launch sub-diffraction beams in free-space at the multi-wavelength range and discuss our latest super-resolution imaging experiments.

Prof. George V. Eleftheriades, Department of Electrical and Computer Engineering, University of Toronto, Canada

19 March 2013, 1530-1730 hrs @ Potential I & II (Fusionopolis, 13th floor, Connexis North Tower), Institute for Infocomm Research

Over the past decade there has been intense interest in artificial materials with unusual electromagnetic properties that cannot be found in nature. Therefore these materials are referred to as “metamaterials” (meta means beyond in Greek). The most representative metamaterial is characterized by a negative index of refraction. The feasibility of media which simultaneously exhibit negative permittivity and negative permeability, hence a negative refractive index, has been known since the sixties. However it is only in the past decade that people invented ways to realize them. In this seminar we will first describe the fundamentals of transmission-line metamaterials (MTMs). We will then present a number of device applications of transmission-line metamaterials including leaky-wave antennas, small multi-band MTM-inspired antennas, reduced mutual-coupling antennas for MIMO, non-Foster antennas, multi-band/broadband passive and active RF/microwave components, and broadband cloaking.

Integration of all photonic components on a single solid state platform has long been a critical issue for optical community. One of the most promising techniques for optical integrated circuit is the Photonic Crystal (PC) technology. In the recent years, emerging PC technology compatible with Complementary Metal-Oxide Semiconductor (CMOS) technology, has paved the way for implementation of an integrated hybrid optics and electronic circuit. Using PC, compact optical elements can be implemented on a solid state platform. The bottleneck of this technology and in general optical integrated circuit is the strong polarization dependence of wave propagation. Thus, the performance and propagation characteristics of the integrated circuit elements are polarization dependent. Hence, our goal here is to overcome the polarization sensitivity of PC integrated circuit by introducing integrated PC based polarization controlling devices that are capable of controlling and manipulating of the polarization of the propagating wave. One of the crucial elements of polarization controlling devices is the polarization rotator. The polarization rotator is utilized to manipulate and rotate the polarization of light. In this work, we have proposed, designed and implemented an ultra-compact passive PC based polarization rotator.
Passive polarization rotator structures are mostly composed of geometrically asymmetric structures. The polarization rotator structure here consists of a single defect line PC slab waveguide. The geometrical asymmetry has been introduced on top of the defect line as an asymmetric loaded layer. The top loaded layer is asymmetric with respect to the z-axis, the propagation direction. To synchronize the power conversion and avoid power conversion reversal, the top loaded layer is alternated around the z-axis periodically. The structure is called periodic asymmetric loaded PC slab waveguide.
We also extended the method to SOI based PC membrane technology for sub-mm/THz applications. The device layer is made of highly resistive silicon to maintain low loss propagation for THz wave. The PC slab waveguide and polarization rotators were fabricated employing this technology. Finally, a-SiON based PC slab waveguide structures were also fabricated at low temperature for optical applications. This technology has the potential to be implemented on any substrate or CMOS chips. 

Due to the rapid growth of the bio-sensing and the imaging application systems, the interest in the development of compact and flexible sub-mm/THz radiation sources has grown significantly. In this work we propose a novel source design to address this need. Taking advantage of the Photonic Crystal (PC) structure’s propagation characteristics, a metallic defect-PC, with no axial discontinuities, was designed as a Slow Wave Structure (SWS). The SWS was then used in a high power Cerenkov-transition based oscillator/amplifier working in sub-mm/THz frequency regime. The designed SWS allows electron beam to travel axially in it, facilitating the beam-wave interaction required for the desired signal generation. Two coaxial transitions are used as input and output ports for the proposed device. The analysis of the proposed device was done using a combined Finite Difference Time Domain (FDTD) / Particle-In-Cell (PIC) simulation. Using the FDTD thin wire model, coaxial transitions were modeled to feed/extract the input/generated signals. To show the potential of the proposed device, two design examples; one for the amplifier and the other for the oscillator, are presented. Although the practical implementation has not been undertaken yet, other experiments reported in literature required an electron gun (75Kv and 6.8A), which is almost 5 times the requirements in our design.

Mr. D. Lesselier, Laboratoire des Signaux et SystèmesCentre National de la Recherche Scientifique (CNRS), SUPELEc-Univ., Paris-Sud Univ., France

12 March 2013, 1400-1600 hrs @ Franklin Seminar Room (Fusionopolis, 11th floor, Connexis South Tower), Institute for Infocomm Research

The presentation will attempt to outline some key issues in Non-destructive Testing and Evaluation (NdT-NdE) and corresponding advances in electromagnetic modeling, with some attention, in particular, being devoted to fast non-iterative imaging and to adaptive database tools. Special focus will be also on a research work on-going about the modeling of the electromagnetic response of anisotropic, fiber-reinforced panels, such panels being increasingly found in aeronautic and automotive industries, and tested/evaluated either via eddy current sensors or microwave sensors depending upon their material characteristics. This will in addition allow the speaker to emphasize the strong co-operation established between his laboratory and Singapore entities and opportunities thereof. Overall, it is expected that the audience should get a fair idea of Ndt-NdE needs and complexities in electromagnetics, while being presented some upstream solutions in the modeling field.

Metamaterials have entered into the mainstream of electromagnetics, high-frequency engineering, and materials science research within a relatively short period. Even if the rapid progress in this field owes very much to earlier studies, it has managed to find a distinct profile and visibility within the first decade of the 21st century. Seminars, workshops, sessions, and even congresses dedicated to metamaterials are being organized, and the journal Metamaterials, published by Elsevier, runs already its third yearly volume. Several books on the topic have appeared during the latest years. The potential for applications of metamaterials in the nanoscale, by manipulation of optical waves, has given rise to the field of metatronics. The prominence of metamaterials research wave is affecting the way electromagnetics problems and questions are approached even to the extent that one may talk about a metamaterials paradigm in research. The essential property in metamaterials is their unusual and desired qualities that appear due to their particular design and structure. These advantageous properties are not straightforward linear functions of the constituents from which the metamaterial is built up. A sample of metamaterial is more than a sum of its parts, analogously to the taste of ice-cream, which is not a direct sum of the flavors of ice and cream. Taking a more general perspective, we may observe that in the field of electromagnetic materials, there are several examples of media that fully deserve to be labeled metamaterials. Chiral (spatial-parity-breaking structures) materials, artificial magnetism, magnetoelectric materials, percolation processes, extremely anisotropic media, and other special media are complex enough to fall in the category of metamaterials. This lecture discusses fundamental issues associated with metamaterials, like possibilities to find a unique definition for them, the spatial scales and geometrical constellations for which one can talk meaningfully about metamaterials, and meta-type characterization of engineering structures and systems in general.

This talk will give a brief introduction to fundamentals of military radio communications from a communication guru with comprehensive practical experience from the leading defense company. The talk will cover the origins and history of radio, antenna and coding applications, system architecture and design considerations. The speaker will also share his experience and lessons in developing some big projects.

High-gain and high-performance waveguide slot arrays in millimeter-wave band are being developed in our laboratory for commercial applications. In the first half of this talk, the realization of a plate-laminated double-layer waveguide slot array in Q-band will be presented. The antenna is designed for a broadband point-to-point fixed wireless access (FWA) system with the maximum throughput of 1 Gbps. The designed antennas are fabricated by diffusion bonding of laminated thin metal plates, which is a promising process of high-precision and high mass-productivity. In a practical manner, the installment of antenna on the wireless terminal as well as the isolation enhancement between two antennas for simultaneous transmission and reception are also investigated. In the second half of this talk, an E-band waveguide slot array with a larger bandwidth will be presented. A PMC termination associated with the symmetry of the feeding waveguide is newly proposed to realize dense and uniform slot arrangement free of high sidelobes. A 16x16-element array with uniform excitation is designed and fabricated by diffusion bonding of laminated thin copper plates. The antenna efficiency of 83.0% is measured at the center frequency. The 1dB-down gain bandwidth is no less than 9.0% and a wideband characteristic is achieved.

As the data rate increases to tens of gigabits per second, the interference issues risen from printed circuit board, bonding wires, various of interconnects and electrically small antennas becomes more and more critical to designers. Accurate modeling of these electrical characteristics requires a full-wave description of various electromagnetic (EM) wave phenomena, including mutual couplings as well as radiation losses. On the other hand, the number of radio systems in a wireless handheld device has been increased rapidly. How to better understand the mechanism of the interferences and the issues of radiation efficiency vs antenna geometry from circuit point of view become crucial. To meet the needs, a full-wave circuit representation of the problems would never be complete without considering the radiation effect.
In this talk, a new generalized partial element equivalent circuit (PEEC) formulation will be introduced first for a full-wave circuit representation of a general multi-conductor problem with not only inductive and capacitive couplings but also the radiation effect. In this frequency-domain formulation, the imaginary part of the generalized complex partial inductance takes account for the radiation loss by means of a frequency-dependent resistance. It will be shown that, for a short electric dipole in free-space, the contribution to the radiation effect in the PEEC model is exactly the same as the radiation resistance of a short dipole antenna learnt in the classical antenna theory.
Then, the concept of the generalized PEEC will be extended to an accurate description of the radiation resistance for a small dipole on microstrip substrate. Using the semi-analytical Green’s functions for microstrip substrates, the imaginary part of this complex inductance can be shown to represent a frequency-dependent resistance containing contributions from spatial radiations (spherical and lateral) and surface waves (cylindrical). It is the first time that the composition of radiation power from various waves for a microstrip structure is revealed. Finally, the generalized PEEC model is used as a starting point to extract a Derived Physically Expressive Circuit (DPEC) model of an electrical small antenna, from which the radiation resistance and efficiency can be easily found.

Radio Frequency IDentifcation (RFID) is one of the fastest growing technologies in recent decades. RFID is an omnipotent identification technology that has many significant applications. As for an example, car immobilizers use RFID technology. However, the penetration of RFID in low cost item level tagging is hindered due to its high cost. The application specific integrated circuit (ASIC) micro-chip in the RFID tag is the most expensive item in a tag. Researchers have been working to remove the chip from the tag so that the tag can be made fully printable and low-cost. However, printing microwave circuits on low grade packaging and labeling materials is not a trivial task. Tremendous design flexibility and high precision printing with high conductivity ink are needed to design microwave circuits on these materials. Additionally to these stringent requirements, reading of this tag is tremendous challenging due to its low fidelity response. No conventional protocols can be added in the chipless RFID tag as they have no on-board signal processing capability. Therefore, a fully new development of chipless RFID reader is needed. This seminar will present chipless RFID tag and reader for low cost item level tagging.

Microwave filter is a compulsory sub-system in all the communication systems. Its electric properties and characteristics decisively determine the overall performance of a communication satellite and a wireless communication network. To meet the high demand on more stringent frequency selections, faster manufacturing turnaround, and more compact size, researches for a better understanding of the business from the theory to practices are never stopped.
This talk will focuses on the recent research progress in microwave filters in The Chinese University of Hong Kong. Although the theories and techniques to be presented are for advanced non-planar microwave bandpass filters and multiplexers in particular, the basic principle is also applicable to planar filters in general.
The contents of this presentation consist of three parts: (1) the latest progress on the analytical synthesis of a microwave filter that optimally matches to a frequency variant complex load will be presented first; a direct application of this theory is the optimal synthesis of microwave diplexers and multiplexers; (2) the generalized inverter model that relates the synthesized coupling matrix and the EM parameters for automatic design of dual mode circular waveguide filters and multiplexer (MUX), with which solving the challenging problems such as spurious mode issue in designing wide band contiguous multiplexers using dual mode circular waveguide channel filters for satellite communications becomes very straightforward; (3) a new dual TM11 dielectric resonator filter architecture will be also presented. In the new architecture all the coupling elements including inter-cavity coupling elements are accessible from the top lid of the filter cavity; and (4) the basic concepts in analytical microwave filter computer-aided tuning (CAT) technique will be presented. The CAT technique, which allows a deterministic tuning of narrowband resonator coupled filters, is a very useful tool for enhancing the productivity and bridging the synthesized filter circuit model and the real world filters.