ABSTRACT. This paper presents an overview of the recent advances we made in the field of microwave sensors. Sensors for different physical quantities are presented, ranging from structures for the retrieval of the electric and magnetic characteristics of materials, to devices for the determination of position and angular rotation. These sensors are based on various fabrication technologies, including planar structures, additive manufacturing, and hybrid solutions, which take advantage of the best features of different technologies.

ABSTRACT. This talk presents a study of near-field radiometry for internal temperature measurements of the human body. Radiometry is shown to be a feasible method for implementing a portable or even wearable microwave thermometer. One of the possible frequencies of operation is the 1.4 GHz quiet band, which is appropriate for centimeter penetration into tissues with minimized radio-frequency interference (RFI). The total blackbody power from a tissue stack is received by a probe placed on the skin, designed to receive a high percentage of the total power from a buried tissue layer. Temperature retrieval for sub-surface tissue layers is performed using near-field weighting functions, obtained by full-wave simulations with known tissue complex electrical parameters. Measurements are presented using a calibrated Dicke radiometer at 1.4GHz for various phantom tissues. It is shown that temperature can be tracked within a fraction of a degree for a phantom muscle tissue layer under phantom fat and skin layers.

ABSTRACT. The emerging scenarios of 6G and, on a longer term, of Future Networks (FN) will pose challenges that cannot be addressed relying on standard design and development approaches. The network is expected to turn into a system of systems, implementing self-management and self-evolutionary capacities, especially at the edge. This work sketches a prominent role for Micro and Nanotechnologies (MEMS/NEMS) in making visions of 6G and FN possible. A comprehensive description of 6G/FN is developed, along with a reformulation of the concept of Hardware (HW), capitalizing on MEMS/NEMS technologies. Finally, RF-MEMS technology (MEMS for Radio Frequency passives) is reported as an example of 6G/FN enabling solution.

ABSTRACT. The paper presents results of analysis aimed to increase gain of planar PCB antenna arrays through combining fewer complex arrays into bigger antenna systems. Analysis starts from 256-antenna elements arrays and investigates various aspects of combining few such antennas into bigger arrays - like number of antennas, topology, efficient low loss microwave power transfer and combining, current distribution aspects etc. Analysis shows that there is a room to increase gain of planar PCB antenna arrays to levels above ~30dBi and proposed approach could be used to fulfill requirements for nowadays demanding perimeter surveillance and security radar applications.

ABSTRACT. A new feeding method of the crossed slot antenna is introduced in this paper. The crossed slot antenna consists of two identical rectangular parts slots positioned at the right angle, at the upper side of the substrate. It is fed by microstrip line on the opposite bottom substrate side without the influence on the desired radiation pattern of the slot antenna. This new method of feeding is compared with uniplanar feeding method by coplanar waveguide line (CPW). A new feeding method enables almost 2.5 times greater operating range of the crossed slot antenna, defined by S11 parameter, than CPW feeding. Also, feeding by microstrip line has a potential advantage in design of crossed slot antenna arrays with incorporated tapered distribution requested for high gain antenna with low side lobe suppression, as well as scanning antennas with corresponding delay lines which are separated from radiating elements.

ABSTRACT. In this work, we propose an equivalent circuit predicting the reflectance spectra of a resonant metasurface with a pronounced variation of the resonant frequency versus the incidence angle. Two different unit-cell geometries of such a metasurface are compared, and the possibility of using both for sensing of submicron-thick films (analytes) is studied. In contrast to conventional metasurface sensors that rely on a spectral resonance shift, the angle-selective metasurface can be employed for sensing using a single-frequency THz source. The proposed circuit quantitatively predicts the reflectance spectra at different incidence angles and allows calculating the required angle of mechanical rotation of the metasurface that compensates for the resonance shift when depositing a submicron analyte.

ABSTRACT. The realization of the DC-block in the microstrip technique on textiles (felt) is given. A vertical coupling of self-adhesive copper strips without widening of the 50 ohm line was used. Dielectric tapes or just glue of self-conducting copper tapes were used as a dielectric between the joined tapes.

ABSTRACT. The paper presents the use of conductive self-adhesive tapes with conductive adhesive to modify microstrip lines on textiles and create substrate-integrated waveguides (SIW). The SIW structure is without via holes and use tapes with conductive adhesive for shorting edges. Half-mode SIW is chosen as better option. Filter is constructed on half-mode SIW and also modified with tapes with conductive adhesive.

ABSTRACT. Future Railway Mobile Communication System (FRMCS) is defined by the International Union of Railways as a telecommunication standard to provide more sustainable railway services. FRMCS will drive the digitalization of railway transportation and will support rail innovations to meet the increasing service demands. The FRMCS design applies the layered approach and make a clear separation between the transport stratum, service stratum and application stratum. The FRMCS specifications define the requirements of FRMCS applications and adopt 5G mobile communications to provide the required connectivity. The realization of the service stratum, which will be based on Service Based Architecture, is regarded as a topic for further study. The paper presents an approach to design the FRMCS system in the form of microservice architecture. The presented approach defines the reusable by different FRMCS applications functionality as loosely coupled microservices tailored to the specific needs of the railways. The microservices communicate through RESTful application programming interfaces to constitute the railway applications which provides more flexibility, resiliency, and scalability.

ABSTRACT. The article investigates the connectivity issue of the digital economy and society index which covers indicators of digital performance. The aim of this research work is to investigate the current connectivity assessment of local communities in the Republic of Serbia. Assessment is based on key connectivity indicators. The results showed that local self-governments in Serbia have low and medium connectivity assessment and a set of measures by decision makers should be done in the process of digital transformation and the development of cities to be the smart ones.

ABSTRACT. Dynamic nature of the IoT data can often cause machine learning model degradation, which can lead to analysis and actions failures. In order to address this challenge, it is of utmost importance to detect drifts in the data that can cause unwanted behavior of the system, and to update models accordingly. This paper gives an overview of different methods for addressing concept drift detection and adaptation, demonstration of some of the methods using open source libraries, and a design for a component for smart adaptive system for streaming data analysis that uses presented techniques to ensure high model performance.

ABSTRACT. With the increased demand for additional bandwidth, when it comes to the Metropolitan Area Networks, there is also a growing need to keep the local traffic local. Preventing the traffic of local origin from “spilling” over the MAN borders, or maybe even country borders become one of the very important tasks. This is where local Internet Exchange Points can help. This paper illustrates possibilities local IXP implementation has to offer (city of Nis, Serbia in this case) and improvements that can come out of it.

ABSTRACT. This article is devoted to the consideration of the so-called SSD trilemma of the blockchain. The article suggests the choice and justification of numerical coefficients of the three main indicators of blockchain platforms, such as scalability, security, and decentralization. The article also provides three types of optimization tasks, as well as a generalized efficiency evaluation indicator for solving the SSD trilemma of the blockchain.

ABSTRACT. This article is devoted to the development of ways to solve one of the main problems of all modern blockchain platforms – the problem of scaling. The authors consider using the segmentation of the blockchain network for this purpose by dividing it into separate segments – the so-called shards. Each shard is, in fact, a separate blockchain with its state. Sharding is undoubtedly one of the most difficult solutions, but also the most promising solution to ensure linear performance growth of modern blockchain platforms.

ABSTRACT. Concatenated codes are effectively used in different approaches of error-correcting theory. We suggest new concatenated code construction that is composed of outer LDPC code and a particular designed inner LDPC code. Special optimization procedure was developed to obtain inner code with specific error-correcting characteristics. We apply the decoder of woven codes to this construction and improve the performance of our scheme with puncturing the code symbols. The resulting concatenated construction outperforms low-rate LDPC from the 5G standard. Besides this, we demonstrate the performance of code with a special parity-check matrix consisting of parity-check matrices of inner and outer codes from our suggested construction.

ABSTRACT. In a recent paper, the authors proposed algorithms for embedding and extracting digital watermarks and theoretically investigated the effectiveness of the attack detection method. It is assumed that some certificate (paper or plastic) is used to guarantee the high quality of the item, provided that the following certificate can be copied, printed and applied to other but similar items (usually of lower quality) in order to falsify prices for real things and, as a result, get some benefit from the sale. In this article, we recall the results of the previous paper and present the results of experiments obtained using a real scanner and printer. Comparison of experiment and theory shows their acceptable agreement under some additional conditions. This fact confirms that the proposed method can be effectively used in practice.

ABSTRACT. An application of data science on analysis of phonograph records in radio broadcasts is presented. Published schedules of Radio Belgrade Yugoslav folk song records broadcasts 1931-33 are analyzed. Data cleansing and imputation processes are described. Several examples of analyses and visualizations are shown, including most frequently broadcast labels, performers, songs frequencies distribution, etc. The proposed methodology is applicable on analysis of radio and TV schedules in general.