Projects

It is well-known that in modern wireless communications (UMTS - Universal Mobile Telecomunication System, HSDPA - High Speed Downlink Access, CDMA - Code Division Мultiplex Access, WiMAX - Worldwide Interoperability for Microwave Access, WLL - Wireless Local Loop, DVB - Digital Video Broadcasting) there are problems of use of limited frequency spectrum and interference. Also, the mentioned systems are used in mobile communications, which additionally complicates mentioned problems. The same applies to various wireless sensor systems. One important measure to solve these problems is to use antennas or antenna systems that enable space selection i.e. control of radiation direction, optimization of beam(s) width, sufficient attenuation of adjacent frequency bands as well as adjustment of correspondent polarizations. Today, this research represents the most prominent field of interest related to antennas.

Metamaterials, especially left-handed metamaterials (LH MM) as well as Electromagnetic Band Gap (EBG) structures provide the new strategies in antenna miniaturization, multi-band operation, scanning without the use of classical phase shifters, etc. could provide a substantial contribution to research and development of mentioned antenna systems. This project deals mainly with research, development and realization of antennas and antenna systems at 2.4, 3.5, 5.2 and 24GHz bands. Because of increased use of mm bands above 30GHz, the project proposes also the research of antenna systems at ranges between 60 and 90GHz.

Project Coordinator (Principal Investigator)

Dr Branka Jokanovic

Project participants

• Institute of Physics, University of Belgrade
• Institute IMTEL, Belgrade
• Faculty of Electronic Engineering, University of Nis
• Innovation Center of Advanced Technologies (ICAT), Nis

Connecting the sensor devices in a network has proved useful for automation and optimization of numerous projects, mostly in agriculture and environmental protection. The core element of the IoT concept is a sensor network whose design is in the focus of many researchers and innovators today. Energy is an essential resource limitation of sensor devices, since their sources of power are usually batteries with limited capacity.

One approach to increase the energy efficiency of the sensor network is energy harvesting. This is a new concept that implies the collection and storage of ambient energy from various sources, in this case collecting ambient electromagnetic energy in the microwave frequency band (RF energy harvesting).

The requirements of the sensor nodes for autonomous and stable power supply are placing the possibilities of this technology in the forefront. So far, widespread solar power has been showing numerous shortcomings. In the case of monitoring in agriculture, it often happens that the solar panel is covered with mud and foliage, with reduced efficiency in the winter due to the lack of direct sunlight.

The proposed energy harvesting concept is based on the acquisition of ambient electromagnetic energy using the antennas designed for broadband operation at several frequencies with integrated detector (rectifier), that converts microwave energy to DC. These antennas are usually reffered as rectennas (rectifier + antenna) in the literature. Energy of the collected microwave radiation does not depend on weather conditions or the current season. Collected RF energy is converted by means of RF-DC converters to a DC voltage that charges the battery, or in the case of advanced versions with low-power microcontrollers powers the entire sensor node. The advantages of the RF energy harvesting are: a) easy maintenance of the sensor network - in contrast to batteries, the lifetime of the sensor can be very long if the system is well designed and with constant source of ambient energy, b) it can be used as an auxiliary power which increases reliability of the system, c) it provides the possibility of autonomous power supply of sensor devices.

Bilateral project between Republic of Serbia and Federal Republic of Germany

Project Coordinators (Principal Investigators)

• Dr Branka Jokanovic (Serbia)
• Prof. Thomas Zwick (Germany)

Project participants

• Institute of Physics, University of Belgrade, Serbia
• Institut für Hochfrequenztechnik und Elektronik, Karlsruhe Institute of Technology, Germany

This project (5G-MultiScan) targets the bilateral collaboration and exchange of young researchers between two groups, one from the German Institute for High Frequency Technology and Electronics, Karlsruhe Institute of Technology (IHE KIT) and the other from the Serbian Institute of Physics, University of Belgrade (IPB). Both groups and the respective institutions are internationally recognized National leaders in their field of research. For more details on the German partner see www.ihe.uni- karlsrue.de, while the internet presentation of the Serbian partner can be found at www.ipb.ac.rs and http://metagroup.ipb.ac.rs. Within 5G-MultiScan, a collaboration based on complementarities will be established between the IHE KIT team having unique experimental skills and facilities in millimeter wave technology and the IPB team that is the regional leader in theoretical modeling and design of metamaterial based structures and antennas. IHE KIT and IPB work on similar topics within their national research projects. Next generation of mobile networks (5G) is expected to utilize higher mm-wave frequencies to achieve promised increase of data-rates and capacity. This poses significant challenges for future 5G systems due to higher propagation losses in mm-waves, especially in the case when there is no direct Line-of-Sight. Possible solution is to use MIMO beamforming gain to offset the losses, however it is unfeasible to scale existing MIMO digital beamforming due to power and cost limitations. Therefore, hybrid MIMO is proposed, where the beamforming processing is split over both analog and digital domains. Analog beamforming is equivalent to beam steering, so, in the frame of 5G, there is great interest in electronically scanned antennas. Standard phased antenna arrays are very complex and expensive due to the large number of ferrite or semiconductor phase shifters. The project goal is to devise an operating principle, the advanced methodology and tools for the efficient simulation and design of simple and low cost mm-wave multi-beam and scanning antennas using: (i) advanced printed antenna arrays, (ii) cheap metamaterial-based phase shifters, (iii) innovative dielectric lenses and (iv) passive multi-beam system architecture. This will be realized by combining the experimental expertise of the German partner and the theoretical skills of the Serbian side.

COST Action CA16220

Next generation global telecommunication platforms and emerging massive take-up applications in radar, communications and space industries will require entirely new technologies to address the current limitations of electronics for massive capacity and connectivity. Multigigabit-per-second 5G wireless communications, the Internet of Things, the upcoming Smart Car scenarios and satellite payloads will require a full convergence between optical fibre and wireless segments.

Microwave photonics (MWP) combines RF and photonics and is the best positioned technology to carry out this convergence. Current MWP systems, however, are fiber and discrete-component based, which limits energy-efficiency, flexibility and scalability, and, as a result, high volume application. Integrated Microwave Photonics (IMWP) seeks to address these limitations by incorporating these systems into photonic integrated circuits (PICs). IMWP is still at its infancy and a considerable body of knowledge, technical and scientific roadmaping and interactions between industry academia need to be developed during the next years.

The European Network for High Performance Integrated Microwave Photonics (EUIMWP) Action aims to shape and bring the relevant IMWP community supporting coordination and networking actions to consolidate this new IMWP ecosystem, providing exchange of knowledge, ideas and delivering a portfolio of technological benchmarkings to establish performance indicators defining future technological requirements in high performance scenarios such as 5G, automotive and aerospace technologies. The action brings together groups from academia, industry and transnational organizations with complementary competences and on a global scale including PIC and MWP experts, microwave system application designers and end-users to fully develop the synergies required by this new paradigm.

Subprojects

• Development of efficient models, based on artificial neural networks, for adaptive antenna structures and EM wave propagation. Development of special antenna structures. Electromagnetic compatibility (EMC) problems solving through development of suitable numerical tools and experimental methods. Design and development of indoor EMC measurement setup;
• Development and applications of advanced modeling techniques, based on artificial neural networks, for the design of wireless communication circuits. Experimental verification of the developed methods for linearization of Doherty amplifiers;
• Microwave structure modeling and response calculation by using wave digital approach. Combining of EM and wave digital approach with methods for lumped circuit analysis for efficient design, modeling and optimization of fast analog and digital electronic circuits in modern systems. Utilization and developments of new numerical methods for applied electromagnetic applications. Development of broadband microwave bandpass filters;
• Research, development and realization of a new high capacity link in millimeter range at about 80 GHz, for solving actual problem of interference and increase the transfer capacity in modern wireless 3G and 4G networks.

Project Coordinator (Principal Investigator)

Prof. Bratislav Milovanovic

Project Coordinator (Principal Investigator)

Dr Brana Jelenkovic

Subprojects

• Holographically-generated photonic and bio-mimetic nano-structures;
• Metamaterials with negative refractive index for light slowing and confining;
• Dissipative and self-organized structures in nano-composits;
• Laser synthesis and modification of nano-composits, metal and semiconductor materials;
• Active EIT materials in photonic structures;
• Nonlinear microscopy for cell and tissue monitoring and manipulation.

MetaGroup subproject

Metamaterials with negative refractive index for light slowing and confining

Periodical structures and amorphous metamaterials will be fabricated, as well as metamaterials inspired by electromagnetically induced transparency (EIT) phenomenon, chiral metamaterials with negative index of refraction where permittivity and permeability are non-negative, and also PhC with negative refractive index. For the realization of photonic metamaterials, direct laser lithography will be used (both commercial and developed systems) as well as nano-imprint lithography and pulsed laser deposition. The software for the extraction of the effective electromagnetic parameters in isotropic and bi-isotropic (chiral) metamaterials will be developed, as well as a method for measuring complex both transmitance and reflectance in visible spectrum. The aim of the research is to generate the samples of 2D and 3D functional materials in optical and terahertz ranges for microscopy, telecommunications and bio-chemical sensors.

Bilateral project between Republic of Serbia and Kingdom of Spain

Passive components and circuits present a bottleneck in miniaturization of wireless systems, as well as impose restrictions on the system performances. Furthermore, in the case of multiband wireless communication systems, operational frequencies are typically separated by various nonharmonic frequencies, not achievable by the use of conventional multiband components.

This project encompasses two main aspects of innovativness. The first one refers to the development of new concepts and design methodology for reconfigurable, multiband devices for wireless communications and sensors. The second one refers to the application of metamaterials in design of reconfigurable, multiband devices.

In order to facilitate the design of devices based on 1D or 2D periodic structures made of metallic inclusions of various shapes, it would be very useful that designer has on disposal the simple circuit-like models such as those we intend to develop in the frame of this project. The Spanish group has developed a methodology to characterize relatively complex periodic structures by means of a few circuit parameters whose physical meaning is quite clear. This methodology could be extended to account for the behavior of other 1D or 2D geometries of interest for the Serbian partner. This would be one of the objectives of this project.

The research project will be organized around three main directions: filtering, antennas and frequency selective surfaces, which will develop systematic routes that transform advanced concepts into industrially applicable devices with unparalleled performance.

Project Coordinators (Principal Investigators)

• Dr Branka Jokanovic (Serbia)
• Prof. Francisco Medina Mena (Spain)

Project participants

• Institute of Physics, University of Belgrade, Serbia
• Department of Electronics and Electromagnetism, Faculty of Physics, University of Seville, Spain

In this project the latest technology is applied based on metamaterials-artificial periodic structures, which show electromagnetic properties that are generally not found in nature. Metamaterials consist of miniature cells whose dimensions are less than one tenth of the wavelength of the propagating signal. Due to such small constituent elements, metamaterials can be treated as a continuous medium with effective permittivity and permeability. By a suitable selection of the type and layout of the constituent elements, the effective parameters of the metamaterials can be arbitrarily large, small or negative. Of particular importance are double-negative or left-handed (LH) metamaterials, which at the same time show negative permittivity and negative permeability in a certain range of frequencies. Thanks to the enhanced dispersion of left-handed metamaterials, it is possible to design circuits that simultaneously work on two or even three arbitrary frequency ranges.

The aim of this project is to develop dual-band and triple-band circuits and antennas using innovative concept of left-handed (LH) metamaterials for a new generation of microwave links. It is well known that microwave links operate in strictly defined bands, which are not in a harmonic relation, according to the ITU-R recommendations. The idea is to design microwave link that will able to operate in two or three different frequency bands using the same hardware. As the price of microwave links is constantly declining due to the high competition in the mobile telephony market, it appears that the application of new technologies is the only way of survival of small producers.

Project Coordinator (Principal Investigator)

Dr Branka Jokanovic

Project participants

• Institute IMTEL, Belgrade
• Institute of Physics, University of Belgrade
• Faculty of Technical Sciences, University of Novi Sad
• Faculty of Electronic Engineering, University of Nis
• Faculty of Electrical Engineering, University of Belgrade