Invited Speaker Program

European Research New Trends
Andreu Mas-Colell, Secretary General of the European Research Council

The interactions between education, research and competitiveness (innovation, industry) will be analyzed in an international context. Research in Europe will be addressed and some of its main characteristics discussed, including strengths and weaknesses. In this context the policies of the European Research Council (ERC) will be presented, with an emphasis on its universality of coverage. 

Industrial Antenna Research
Nick Alexopoulos, Broadcom (Univ. Californ. Irvine)

Knowledge, in all of its  manifestations , establishes the foundation of our society. However, without  its  transformation  through technology into various forms of human activity it is essentially evanescent.  Technology, albeit in it's most primitive stage, must have emerged simultaneously with the first humans  as a primary need for survival. Since that time, it has been an integral part of evolution always propelling humans to a higher status.  It is a fact that the periods of human history are defined and distinguished by a critical technological advancement.  We are present now within the Information Age  not only as active participants but also as contributors to it's evolution through the technologies  provided by Engineering Science . It is within this context that I will discuss the Pyramid of Knowledge , how Engineering Science makes all human activities possible , and how Engineering Science education must be connected to industry through the theme of University-Industry Relations.   
I will provide my personal experience of the necessary evolution  of this theme  in the modern era . I will use as an example my practical experience as a faculty member and administrator at UCLA. I will briefly  highlight  the emergence of several high tech companies. I will then focus on  Broadcom Corporation, and its  rising  impact to our society in general but especially through the support of faculty and  student research at many universities.
Since this is a conference on Antennas and Propagation, I will mention current progress in Broadcom's development of antenna products. Being in  Barcelona, a major centre of fractal antenna theory and design , I will summarize our activities in the design of miniaturized elements using a special fractal geometry and the use of this fractal for filter, metamaterial and absorber design. I will  furthermore discuss novel Broadcom single and dual band MIMO  antennas, our efforts on Tracking Radar on Chip, and I will conclude with our pioneering work on the concept of Projecting Artificial Magnetic Mirrors and their potential application for WLAN and 60GHz antennas.

A New CEM Algorithm for Solving Real-world Antenna and Scattering problems
Raj Mittra, Penn State University (USA)

It is quite well known that computational electromagnetics is a rather mature field. There are a number of well-established algorithms for solving EM simulation problems, such as the Method of Moments (MoM); Finite Element Method (FEM); Finite Difference Frequency Domain (FDFD); Finite Integration technique (FIT); and, the Finite Difference Time (FDTD) method. Of these, the first three are frequency domain techniques that require the solution of matrix equations, which is typically carried out via the use of iterative schemes. For certain types of kernels, such as those associated with perfectly conducting scatterers, the matrix-vector operation required in typical iteration schemes is often carried out efficiently by using the Fast Multipole Method (FMM).
In contrast to the frequency domain methods, CEM algorithms for the time domain solution of EM problems are based upon matrix-free recursive methods, which generate the solution by using a leap-frog scheme. There are advantages and disadvantages of both the frequency and time domain methods, and we will not discuss them here because they are quite well known.
In this paper we will present a new general-purpose CEM algorithm, which combines the salutary features of both the frequency and time domain algorithms, and is called RUFD (Recursive Update Frequency Domain). The proposed algorithm has been designed to handle real-world problems that may be inhomogeneous, involve dispersive materials, and may be multiscale in nature. Illustrative examples would be included in the presentation to demonstrate the versatility, wide-range applicability, as well as numerically efficiency of the RUFD algorithm when compared to the existing methods.

Scattering By Load-Modulated Small Antennas: Background And Sensing Applications
Jean Charles Bolomey, Supelec

This paper consists in a unified and comparative presentation of various scattering load-modulated systems. This generic designation covers different conceptual approaches, which are based on the same scattering mechanisms. Until now, these approaches have been rather separately conducted.
Possible synergy opportunities are analysed in view of microwave sensing applications of practical relevance. Beyond the available state of the art, new procedures are suggested to overcome the limitations of current systems.

The transmission-Line Paradigm for Metamaterials: Fundamentals & Applications
George V. Eleftheriades, University of Toronto

In this presentation we will describe the fundamentals of negative-refractive-index transmission-line (NRI-TL) metamaterials (MTMs) and outline some of their applications. We will discuss the issue of the excitation of spatial harmonics in these structures and show why a single backward-wave can be used to characterize them in the long wavelength limit. Subsequently, we will discuss the origin of the broad left-handed bandwidths and low transmission losses characterizing NRI-TL metamaterials. Results of the phenomenon of negative refraction of Gaussian beams in transmission-line metamaterials will be shown to address recent objections raised against the reality of negative refraction in sub-wavelength periodic structures. Subsequently, we will present selected applications of transmission-line metamaterials including super-lensing in free space, multi-band and active microwave components, peculiar couplers that support complex waves, leaky-wave antennas, and compact multi-frequency / broadband antennas inspired by MTM concepts. Finally we will describe our recent work with closely packed end-fire dipole antennas for achieving sub-diffraction focusing and imaging in the near field. 

Propagation Models for Nano Communication Networks
Ian F. Akyildiz, School of Electrical and Computer Engineering, Georgia Institute of Technology

Nanotechnology is enabling the development of devices in a scale ranging from one to a few one hundred nanometers. Nanonetworks, i.e., the interconnection of nano-scale devices, are expected to expand the capabilities of single nano-machines by allowing them to cooperate and share information. Traditional communication technologies are not directly suitable for nanonetworks mainly due to the size and power consumption of existing transmitters, receivers and additional processing components. All these define a new communication paradigm that demands novel solutions such as nano-transceivers, channel models for the nano-scale, and protocols and architectures for nanonetworks. In this talk, first the state-of-the-art in nano-machines, including architectural aspects, expected features of future nano-machines, and current developments are presented for a better understanding of the nanonetwork scenarios. Moreover, nanonetworks features and components are explained and compared with traditional communication networks. Novel nano-antennas based on nano-materials as well as the terahertz band are investigated for electromagnetic communication in nanonetworks. Furthermore, molecular communication mechanisms are presented for short-range networking based on ion signaling and molecular motors, for medium-range networking based on flagellated bacteria and nanorods, as well as for long-range networking based on pheromones and capillaries. Finally, open research challenges such as the development of network components, molecular communication theory, and new architectures and protocols, which need to be solved in order to pave the way for the development and deployment of nanonetworks within the next couple of decades are presented.

Millimeter Wave Array Antennas
Makoto Ando, Tokyo Institute of Technology, Japan

Novel design/fabrication techniques of high gain waveguide arrays are presented for millimeter wave. It focuses upon the realization of wide bandwidth and high efficiency of the large arrays. The reduction of computational load in the design of large arrays is also discussed.
(Bandwidth widening of the arrays)
An ultra wide band double layer waveguide arrays with a corporate feed is fabricated by diffusion bonding of laminated thin metal plates. In 60GHz band, ultra high    antenna efficiency more than 80% and 1dB-down wide bandwidth of more than 10% are measured at the high gain range of 33dBi. On the other hand, the Long Line Effects in Single-layer Slotted Waveguide Arrays with series feed are reduced by introducing an Embedded Partially Corporate Feed.
(Full-Wave Design of Two-Dimensional Waveguide Slot Arrays with Perfect Input Matching)
A novel design technique for two-dimensional waveguide slot arrays, by using a combination of a full-wave method of moments (MoM) analysis and an equivalent circuit with the explicit restraint of input matching is proposed.  Two 2427-element arrays with uniform and Taylor distributions were designed and fabricated at 25.3 GHz. The measured overall reflections for both antennas were suppressed below -18dB over the 24.3~26.3 GHz frequency range. Aperture efficiencies more than 85% and 55% were realized for the antennas with uniform and Taylor distributions, the latter of which has very low sidelobes, below -30dB.
(Simplified array design using MoM for only dominant mode on slot with equivalent length)
By introducing equivalent slot length instead of actual one, slot design optimization using MoM for only one mode for the slot aperture field attains enhanced accuracy. Since the correction length is almost constant for the changes in slot coupling and for types of slot (shunt, transverse etc), the array design/optimization is straightforward once the correction length is specified for some slot, theoretically or experimentally.

Challenges in Propagation and Channels in the Networks of the Future
Luis M. Correia, IST/IT-TUL, PT

Telecommunications are evolving fast, with many trends being observed at the several layers of the system/network structure.  “Networks of the Future” and “Future Internet” became trends that encompass many views and goals, namely within mobile and wireless communications, most of them related to network aspects, as well as services and applications.  This paper reviews the trends mentioned above, and then maps them onto the challenges that can be identified in the area of propagation and radio channel.  These challenges extend beyond the usual concept of mobile and wireless cellular and local area networks, including application driven areas, like sensor and in- and on-body networks, device-to-device and machine-to-machine communications, and ambient and context awareness.  On the other hand, more “classical” challenges are also at stake, coming from, e.g.: increase in data rates, hence bandwidth, hence carrier frequency; energy efficiency; efficient MIMO/beamforming; channel estimation and awareness; inclusion of antennas.

Mitigation Techniques for Multi-Beam Broadcast Satellite Services
Aldo Paraboni, Politecnico de Milano

The transmission of huge quantities of data required today by the information society has brought to a compulsory need of new and very wide available frequency bands for both Multimedia and Broadcasting transmission. This, in turn, has implied to resort to very high and relatively new frequency bands. Presently the Ka- and, in perspective, the Q/V-bands are the most promising candidates to sustain this trend. This inevitably leads to the necessity to face the strong atmospheric attenuations (oxigen, water vapour. Clouds and rain) encountered at these frequencies without resorting, especially in the case of satellite transmission, to excessive power or antenna gains (the so called “brute force” solution). According to the opinion of many operators today, the way out from these difficulties consists in the adoption of some form of Propagation Impairments Mitigation Techniques (PIMTs) that can assume various forms. One of these is certainly the adoption of multibeam antennas on-board of the satellite for the down link, a countermeasure that offers the possibility to radiate the power in adaptive way by privileging the sub regions affected, at a particular instant, by strong atmospheric attenuation. The paper will concentrate the attention on the broadcasting application, surely the most demanding one in terms of beam-forming network and determination, at a given time, of the excitation coefficients which must be derived from available (and uncertain) meteo information. In addition the driving procedures must face big problems related to the difficulty to work-out, in a reasonably short time, the needed signals to drive the antenna in the two technologies foreseeable today for beam-forming networks: the multi-port amplifiers and the flexible travelling wave tubes. The technical solutions to approach this goal are presented and discussed in the light of the preliminary tests carried out so-far and of the best optimization techniques which have been selected and finalized for this purpose.

Nano-radio and related topics
Peter J. Burke, University California Irvine

In this talk, I will present an overview of nano-antennas for RF frequency ranges. The talk will focus initially on the smallest antenna possible (using a single carbon nanotube), it’s predicted properties, advantages & disadvantages. Next, I will discuss the transition from nano-antenna to classical antenna. Final, I will discuss possibly applications in biomedical engineering, with the realistic potential to build a fully functional radio that is smaller than a living cell. 

Antenna Modeling and Performance on Complex Structures and Airframes
Constantine A. Balanis, Arizona State University

Antenna elements have basic radiation characteristics when they radiate in an infinite medium or in the presence of basic structures, such as infinite ground planes.  When the same elements have to perform in the presence of more complex structures, their radiation characteristics can be altered considerably.  In practice, all of the antenna elements have to perform in the presence of complex structural environments, such as finite ground planes and cylinders, mobile wireless devices, electronic packages, ground based vehicles, airborne platforms (such as airplanes and helicopters), ships, just to name a few.  To model, simulate and interpret the performance of radiating elements in the presence of such complex structures, many methods are available that have been developed over the years.  The method of choice is usually dependent on the complexity of the structure and its electrical size.  In this presentation the performance of basic elements, such as monopoles, apertures, and microstrip patches, when mounted on finite ground planes, ground-based vehicles and airborne platforms are modeled and simulated using high-frequency asymptotic methods [such as diffraction techniques GTD/UTD] and full-wave methods [such as IE/MoM, FDTD and FEM].  While GTD/UTD shed more physical inside into the modeling, they are limited by the types of structures, constituent parameters, and electrical sizes.  Full-wave simulators, such as IE/MoM, FDTD and FEM, are more versatile although usually are limited by physical interpretation and electrical size.  The basic antenna characteristic examined will be radiation pattern formation and distortion due to edge diffractions and rotor blade rotation. Typical amplitude patterns of radiators mounted on complex airframes, such as airplanes, helicopters and even the space shuttle, will be presented.   In some cases simulated data are compared with measurements on scaled-model structures.  

Review on Terrestrial Propagation Channel Modeling
Marlene S. Pontes, CETUC Rio de Janeiro

Design and implementation of wireless systems, comprising mobile, portable and fixed radios, requires the knowledge of the propagation characteristics of the channel. The random nature of the radio channel and the complexity of the propagation phenomena suggest that the characterization of the channel can be achieved based on statistical analysis of field measurements. This approach leads to the statistical empirical models of the propagation channel. Alternatively, deterministic modeling, based on approximate solutions of the wave equation can be applicable in some situations. This paper presents a brief review of propagation effects on terrestrial links and corresponding channel models. It also includes a survey of available measured data for testing of the existing methods and for the development of more accurate empirical and semi-empirical models.
 
For terrestrial systems, channel propagation modeling involves the prediction of the path loss, small and large-scale fading and depolarization effects. Measurements of path loss allow the probabilistic modeling of additional attenuation over free space loss. Additional attenuation is produced by propagation mechanisms such as atmospheric absorption, reflection, refraction, obstacle diffraction, multipath propagation effect, tropospheric scintillation, attenuation by foliage and attenuation by hydrometeors. Multipath fading is the major outage causing mechanism on links longer than a few kilometers operating at frequencies below 10 GHz. On the other hand, precipitation attenuation dominates in microwave and millimeter bands above 10 GHz. The distribution of the received signal during rain depends on the climatic characteristics of the site or region where the link is located. In free space optical channels modeling, atmospheric absorption and scintillation must also be taken into account.

Large-scale fading in narrowband systems can be modeled from single frequency measurements. In clear-air conditions, the log-normal distribution usually describes the behavior of large-scale fading. Small-scale fading occurs mainly due to multipath effects and is characterized by deep and fast fluctuations on the signal envelope in a short period of time or distance. Minor displacements of the receiver modify the relationship between the phases of several components of signal generated by multipath. For mobile communications system, small-scale fading is also influenced by the receiver velocity.

For narrowband channels, the envelope of the received signal can be statistically described by Rayleigh, Rice or m-Nakagami probability density functions. Signals composed only by multiple path components have envelopes described by the Rayleigh distribution. Signals composed by multiple path components and a line-of-sight component are statistically described by Rice or m-Nakagami probability density functions.

For wideband modeling, the channel impulse response can be represented as a sum of weighted delta functions, each component corresponding to a propagation path. The channel is usually described by the power delay profile and several related parameters as the RMS delay spread and mean delay spread in the time domain, and the Doppler spectra in the frequency domain [3]. A channel exhibits frequency-selective fading when the delay spread is greater than the symbol period. This condition occurs whenever the multipath components of a received symbol extend beyond the time duration of the symbols. When the delay spread is less than the symbol period, a channel is said to exhibit flat fading, and there is no channel induced distortion. But there can still be performance degradation, due to irresolvable phasor components that add up destructively resulting in substantial reduction in signal-to-noise ratio at the receiver.

Antenna Measurement Range Characterization and Compensation
Ed Joy, Georgia Institute of Technology, Georgia, USA

This paper reports on research at the Georgia Institute of Technology to compensate test zone fields of fixed-line-of-sight far-field, anechoic chamber, compact and near-field antenna measurement ranges for measured imperfections in the amplitude, phase and polarization of the test zone fields of these antenna measurement ranges.  Knowledge of the amplitude, phase and polarization of a test zone field throughout a spherical test zone volume is obtained by outward probing over the surface of the test zone sphere to measure the amplitude, phase and polarization of all fields entering the test zone from all intentional and unintentional range sources and from all directions. The spherical surface probing measurements are expanded into spherical modes and compensated for the pattern and polarization of the probe.  The spherical mode spectrum is used to determine the field at any point within the test zone volume and to determine the plane wave spectrum of the total field entering the test zone volume. The response of an antenna-under-test (AUT) located within the test zone of the range can be thought-of as the sum of the responses of the AUT to each of the incoming plane wave sources. Thus this sum has only one unknown: the complex, vector pattern of the AUT and the sum equals the measured complex vector response of the AUT as rotated throughout the test zone volume.  This sum is solved using a described iterative technique.  The number of iterations is typically three or four.  Measured results are presented for a phased array antenna measured on a quasi far-field anechoic chamber range.  These results show an effective range reflectivity reduction of over 20 dB.

Computational Electromagnetics
Weng Cho Chew, University of Hong Kong

In the beginning, electromagnetic analyses, like many science and engineering analyses, were done with pencils and papers. Closed form solutions were sought. Later on, approximate solutions were sought. With the advent of computers, computer solutions were sought. This development not only happens in electromagnetics, but in other fields in engineering and science, such as computational mechanics, fluid dynamics, and physics.   Nowadays, computational electromagnetics replaces pencil and paper analyses.   Computational electromagnetics has changed how modern-day scientists and engineers work as electromagnetic simulation tools are used as a virtual laboratory where ideas can be tested, and virtual proto-typing can be performed.

Unbeknownst to many, much physical insight of wave and field physics is needed in order to design fast and efficient algorithms for computational electromagnetics. We will discuss some of the pertinent physics involved relevant to the design of fast computational algorithms.   For instance, wave field is oscillatory and static field in smooth. This difference has affected the development of fast algorithms for computational electromagnetics: it is a lot easier to accelerate static field calculation, but very difficult to develop fast algorithms for wave physics problems.

While wave physics is important in electromagnetics, it is also important in many modern physical concepts such as mesoscopic physics, coherence and decoherence in quantum systems, and Casimir force calculation. When the dimensions of electronic devices are on the order of the mean free path of the electrons, wave physics and interference phenomenon are important in describing the behavior of electrons in these mesoscopic scale devices.  Another wave physics phenomenon that appears in quantum physics is the concept of coherence and decoherence.  For instance, this concept is important in optics in the electromagnetic spectrum because of the short wavelength at optical frequencies.  Due to the high momentum of electrons, the electronic wavelength is much smaller than optical wavelength. This makes the coherence length of electrons to be much smaller than those in optics.  As a result, a quantum system becomes decoherent rapidly.  Again, a quantum system can never be isolated, and the coupling of one quantum system to another rapidly decohere a quantum state.  Hence, the design of quantum computers is extremely difficult.   Lastly, the meaning of nothingness does not exist in quantum electromagnetics, because there is fluctuating electromagnetic field even in vacuum where classical electromagnetics implies zero field. The vacuum fluctuation gives rise to attractive forces between objects that are in close proximity to each other.  We will show some calculations of Casimir force using combination of computational electromagnetics, statistical physics, and quantum electromagntics.

Photonic Antennas
Niek van Hulst, ICFO

Scaling up antennas to the 500 THz frequency (the visible regime), while scaling down to the nanometer scale, opens up the unique opportunity to interface such photonic nano-antennas with single photon emitters: individual molecules, quantum dots, color centers, proteins... The fabrication, losses and dispersion of metals at optical frequencies offer major challenges, yet once surmounted, new avenues in the fields of active photonic circuits, bio-sensing and quantum information technology are opened up.
In this presentation the optical analogue of monopole, dipole, multipole and multi element antennas will be presented, focusing on nanoscale field concentration, femtosecond response, spectral resonances and directionality.
In receiving mode, single molecules are ideal probes of the local antenna field and here we show optical fields spatially localized within 25 nm in the near field of an optical monopole antenna. In transmitting mode, the single photon emitter locally drives the antenna and the emission pattern is determined by the antenna mode; here we show controlled directed emission of photons by photonic monopole and Yagi-Uda antennas. Beyond spatial confinement and directivity, the excitation and emission of single photon emitters (molecules, quantum dots), can be controlled also in time on fs scale. Using broad band excitation (~ 120 nm bandwidth) in combination with a pulse shaper we control individual photonic nano-antennas, adapt to the spectral phase development of the antenna and optimize the driving efficiency or generate local spatial hotspots at the antenna.
Throughout the presentation I intend to build insight in how modern photonics is currently inspired by the hugh variety of antenna designs and optimizations.

Advances in Antennas and Propagation For Body Centric Wireless Communications
Peter S. Hall, University of Birmingham

Research in antennas and propagation for body centric wireless communications continues to grow, in response to increasing demands for body area networks (BANs) for healthcare, defence and personal communications and entertainment. This paper will briefly review recent international work, and then report on advances in three UK BAN research centres, Birmingham, Queen Mary and Queens Belfast. The demand for greater security in BAN links could be met by the use of 60GHz channels, and the likely channel characteristics will be discussed and initial results given. New insights into surface wave excitation on the human body has enabled a novel low profile antenna to be designed that maximises link performance where very thin antennas are necessary. Finally advances in the numerical computation are reported, in which the importance of relating phantoms directly to patients to give subject specific simulations and to allow improved modelling of internal organs.

Channel Model for Land Mobile Satellite Services
Fernando Pérez Fontán, University of Vigo

The land mobile satellite channel, mainly at L- and S-Bands, is currently being used by a number of services including two-way communications, broadcast or navigation. This channel is extremely sensitive to shadowing and multipath effects, making the appearance of new or more evolved services very difficult. Additionally, new bands such as C-, Ku- and Ka-Band are being studied for their possible application in mobile satellite services. In the paper a review of the main features and modeling approaches currently being used to characterize the channel will be presented with special emphasis in generative models capable of producing time-series to be used in simulations of adaptive radio interfaces including fade countermeasures. A number of additional topics will also be covered, including satellite diversity and MIMO channel characterization.

Recent Advances in Reflectarray Antennas
José A. Encinar, Universidad Politecnica de Madrid

For most radar and long distance communications, the need for high-gain antennas is often unavoidable. Traditionally, the types of high-gain antennas have been relying either on parabolic reflectors or on arrays.  However, a third type of antenna, namely the “reflectarray”, has evolved to mitigate some disadvantages associated with either the parabolic reflector or the conventional array. The reflectarray consists of a planar array of microstrip patches on a grounded substrate with a certain tuning to produce a focussed or shaped beam when illuminated by a primary source. Reflectarrays are easier to manufacture than reflector antennas and present less distortion and cross-polarization at the cost of a narrower bandwidth. Comparing to phased arrays, the reflectarray eliminates the complexity and losses of the feeding network and exhibits a higher efficiency.

The talk will be concerned with recent advances in the analysis, design and realisation of reflectarray antennas for some potential applications. Some techniques recently developed for an accurate and efficient analysis of reflectarray antennas in single and dual-reflector configurations will be briefly described. Based on the previous analysis techniques, several design and optimization procedures will be applied to achieve different antenna performances, such as bandwidth, dual-frequency, stringent contoured beams and beam scanning. Finally some recent developments for applications in space and point-to-multi-point antennas will be presented.

UWB MIMO Channel propagation modelling
Andreas Molisch, University of Southern California

The modeling of propagation channels is an essential prerequisite for the design of novel wireless systems. Single-antenna UWB systems have been explored since the late 1990s, and the associated propagation channels are reasonably well understood today. However, constraints on the transmit power and/or the achievable data rate have recently motivated the use of multiple-antenna systems in conjunction with UWB. In this talk, we will review the essential features of UWB-MIMO channels both in the microwave (3-10 GHz) and millimeter-wave (60 GHz) region, as well as various measurement campaigns. We will describe how the directional characteristics can be a function of the considered bandwidth and center frequency. We will also describe some recently-introduced useful tools for geometry-based MIMO-UWB channel modeling.