ABSTRACT. This paper presents recent progress on portable Doppler, frequency-shift keying (FSK) and frequency-modulated continuous-wave (FMCW) radar systems for life activity sensing and human localization. It starts from a software-based calibration technology that significantly improves the accuracy and reliability of millimeter-wave interferometry radar front-end for physiological motion and vocal vibration detection. Then, the operation principle and unique features of FSK and FMCW radar, such as RF/digital beamforming, for human-aware sensing and localization will be presented. To reject clutter noise, which is a common challenge for practical deployment of short-range radar system, intermodulation radar technique will be discussed. Then, machine learning will be presented as an efficient approach to make the radar system smart for automatic classification and decision making. Finally, challenges for biomedical radar systems and future development directions will be discussed.

ABSTRACT. This paper presents an innovative methodology for detecting the presence of a child in the car seat or on the back seat of the vehicle. The goal of this project is to avoid the incidents where children being left inside a car die of heatstroke. The core of the system is represented by a frequency-modulated radar operating within the 79-81 GHz bandwidth. The capability of the system to detect a child or an infant has been demonstrated by means of a properly tailored simulation scenario. Moreover, the transmitting/receiving antenna array has been designed in planar technology and the relevant parameters have been reported.

ABSTRACT. This paper presents a method for determining binary mixing ratio of two liquids for microfluidic applications. The liquid mixtures are measured through sensor constituted by interdigital capacitor. Dielectric permittivity of the fluid is derived from the high-frequency capacitance measurements. Finally, the mixing ratio is calculated using frequency-dependent modified Bruggeman formula. The method is purely measurement-based and does not require electromagnetic simulations. The error for determining the mixing ratio is below 5% at frequencies above 1 GHz for water and isopropanol mixtures.

ABSTRACT. The goal of the research presented in this paper is to develop a fully passive system for detection and transmission of heart rate from an ECG signal, for the monitoring of cardiac health of soccer players during competitions. The proposed system is meant to be disposable, made with commercial components that allow a low-cost solution. For this purpose, it has been chosen to design a battery-free system RFID based. The RFID passive tag is used as an ON-OFF device, that is normally ON and turn OFF every time a heartbeat is detected. The signal is acquired by a piezoelectric sensor which pilots the variation of a variable capacitor inside a tunable bandpass filter.

ABSTRACT. This paper reports on uniplanar interdigital capacitors employed for dielectric sensing in digital microfluidics. Two interdigital capacitors on a microwave chip, a quadrature coupler and a phase shifter were used to build a tunable 2-port network for glucose concentration in DI water extraction using the interference principle. One capacitor in the setup was used as a sensor, while another capacitor was used as a reference. Microwave measurements were carried out at 4.5 GHz using the tunable 2-port network for reference liquids being DI water and a glucose-DI water mixture. Measurement results demonstrated extraction of 0.1 M glucose concentration.

ABSTRACT. A compact ultra-wideband monopole Cardioid antenna based on fractal geometry for energy harvesting applications is proposed in this paper. The antenna is designed for energy harvesting in WIMAX, WLAN and satellite communications ranges. The performance is achieved using the cardioid shaped radiating element on low-cost FR4 substrate. Simulated results show that antenna have S11 value under -10dB in range from 4 GHz to 30 GHz covering almost all SHF band (3-30 GHz). In addition, the gain is up to 5 dBi and efficiency up to 80%. This antenna is very simple for manufacturing has ultra-wide band, high gain and efficiency and therefore is suitable to use in energy harvesting applications. Proposed antenna performance are simulated in time domain based CST solver.

ABSTRACT. A W-Band on-chip monopole antenna with SRR (Split Ring Resonator) and LBE (Localized Backside Etching) in a standard 0.13 μm BiCMOS process is presented. The AMC, composed by the SRR and the LBE, has been inserted in order to enhance the on-chip antenna gain by minimizing the losses of the substrate through the creation of constructive reflections. The enhancement of the gain has been fulfilled by etching the silicon substrate and thus reducing the losses. These etched parts are called Localized Backside Etching (LBE). Despite the other on-chip monopole antennas, the proposed element combines these two techniques to improve the radiation properties of monopole on-chip antenna. The proposed configuration provides a gain enhancement of 1 dB. The final AoC has a compact size of 1.11x1.28 mm2 and provide a peak gain of 2.29 dBi at 83 GHz.

ABSTRACT. In this paper, a Ka-band low-profile Magneto Electric (ME) dipole is presented. The proposed design exploits a balanced microstrip line feed to excite a rectangular slot in the aim of flattering the gain frequency response. Simulated results show that the proposed ME dipole achieves an impedance bandwidth of 24% (S11 ≤ -10dB) from 25.7 to 32.6 GHz. Unlike other ME dipole geometries, this design is obtained using an ultrathin dielectric multi-layer structure as the overall antenna thickness is equal to 0.086 λ0 (λ0 is the free-space wavelength at 29GHz). Bandwidth is improved by adding capacitive loads between the arms of the electric dipole. Radiation patterns with low back-radiation levels and low cross-polarization and a stable antenna gain higher than 8 dBi are reached across the entire operating bandwidth. The radiator shows good performances and it is well suited for 5G mobile telecommunication systems.

ABSTRACT. Compact, printed slot antenna array with series feeding for K-band applications is investigated. A CPW T-junction is employed to feed the antenna consisting of 2 x 8 identical slots of rectangular shape that are positioned asymmetrically relative to the CPW feeding line. The proposed asymmetrical slots offer greater flexibility in antenna design which results in a wide operating bandwidth, maximum 18.3 dBi gain and moderate side lobe suppression. The feed simplicity and planar configuration of slot array, intended for frequency range 24.25-27.5 GHz, makes it attractive for radar sensors and high capacity 5G technology applications.

ABSTRACT. This paper describes in detail the design, prototype realizations and measurement results of antenna array developed for a short-range radar module, operating at unlicensed ISM range within K frequency band. The radar module is suitable for sensing a presence of humans and other living beings inside a confined space by detecting their vital signs. The characteristics of antenna array are specified in accordance with projected working environment of the radar module as well as the characteristics of the Infineon transmitter, employed as major active element. The antenna array is designed for achieving specific beamwidths in azimuth and elevation plane to ensure coverage of entire observed zone from a fixed position of the radar module. Two different types of the feeding networks are designed, differential and single ended, to match the corresponding inputs of the transmitter and to maximize the radiated power.

ABSTRACT. Various responses to non-thermal microwaves (MW) from mobile communication including adverse health effects related to electrohypersensitivity, cancer risks, neurological effects, and reproductive impacts have been reported while some studies reported no such effects. This presentation provides an overview of the complex dependence of the MW effects on various physical and biological variables, which account for, at least partially, an apparent inconsistence in the published data. Among other variables, dependencies on carrier frequency, polarization, modulation, intermittence, electromagnetic stray fields, genotype, physiological traits, and cell density during exposure were reported. Nowadays, biological and health effects of 5G communication, which will use microwaves of extremely high frequencies (millimeter waves MMW, wavelength 1- 10 mm), is of significant public concern. It follows from available studies that MMW, under specific conditions of exposure at very low intensities below the ICNIRP guidelines, can affect biological systems and human health. Both positive and negative effects were observed in dependence on exposure parameters. In particular, MMW inhibited repair of DNA damage induced by ionizing radiation at specific frequencies and polarizations. To what extend the 5G technology and the Internet of Things will affect the biota and human health is definitely not known. However, based on possible fundamental role of MMW in regulation of homeostasis and almost complete absence of MMW in atmosphere due to effective absorption, which suggests the lack of adaptation to this type of radiation, the health effects of chronic MMW exposures may be more significant than for any other frequency range. The data showing dependence of MW effects on extremely low frequency and static magnetic fields at the location of exposure suggested a strategy for reducing health effects from MW of mobile communication

ABSTRACT. Deformation of the natural magnetic earth field by introducing ferromagnetic objects and electrical devices leads to the creation of an anomalous magnetic field in which a person resides. The longest period of time a person resides in bed is in a static position, and according to scientific facts, the magnetic field change has significant impact on health. The paper calculates the magnetic field in a real bed with a ferrite structure and a mattress with ferrite springs. The author also presents the latest scientific findings on the health effects of staying in enhanced magnetic field for longer rest periods during night breaks.

ABSTRACT. Everyday use of mobile phones by children has significantly exposed them to electromagnetic radiation. This has led to public concern about potential adverse effects of electromagnetic radiation. This paper discusses the distribution of the magnetic field from a mobile phone transmitting signals at frequencies of 1.8 and 2.1 GHz through a child head model. Human tissues and organs are represented according to their corresponding electromagnetic properties. These parameters depend on the morphological composition of tissues and on the signal frequency. The paper presents the results of magnetic field distribution for a horizontal cross-section of the child head model at both frequencies.

ABSTRACT. Minimally-invasive techniques for treatment of varicose veins have been introduced during the last two decades, proving to be valid alternatives to surgical techniques. Among them, foam sclerotherapy has represented the most minimally-invasive procedure. Recently, neurological adverse events following foam sclerotherapy have given the push towards the development of new methods for the preparation of foams. In this paper, an indirect sonicated method has been investigated in order to produce stable sclerosing foam. Foams have been produced changing the surfactant concentration and the sonication time. Foam temperature has been experimentally observed using a dynamic device, i.e., a pyroelectric sensor, which is characterized by a faster response than conventional sensors. Promising results have been achieved, allowing to prolong the stability of sonicated sclerosing foams beyond one minute.

ABSTRACT. IoT based laser therapy system is designed to collect data about the therapy protocols from the practitioners and to help them select the therapy parameter values by recognizing in advance the biological effects fostered by the chosen parameter value combination. This paper investigates whether multilayer perceptron can be used to recognize the biological effects on the bases of the proposed therapy protocol values.

ABSTRACT. The performance of simultaneous wireless information and power transfer (SWIPT) is often inhibited by high pathloss and multi-path fading. The massive multiple input-multipleoutput (MIMO) system is seen as an effective technique to overcome the wireless channel distortion. This work analyzes how massive MIMO enables channel hardening and thus influences the optimal SWIPT transmission strategy. This study focuses on the MISO case (i.e., 64-antenna transmitter and a single receiver node) and is done based on a non-linear energy harvesting model and measured channel state information (CSI). The results confirm that massive MIMO hardens the channel which makes frequency domain pre-equalization unnecessary for both nonline-of-sight (NLoS) and line-of-sight (LoS) channels. The impact is, as expected, more noticeable in NLoS scenario. We show that the array gain introduced by the 64-antenna transmitter using a 15-tone multi-sine signal, can improve the normalized power conversion efficiency (PCE) by more than 80%, and the channel capacity by more than 2 times, for both NLoS and LoS channels.

ABSTRACT. Cell-free Massive MIMO (CF-M-MIMO) networks have recently emerged as a promising architectural solutions to satisfy the requirements of future networks (i.e., beyond 5G, 6G). The CF-M-MIMO paradigm advocates for the irregular deployment of a large number of access points (AP) throughout the network coverage area, all connected to a central processing unit (CPU), with the aim of bringing the radio access front-end closer to the users. Indeed, the cell-free topology can be interpreted as a fully distributed implementation of the Massive MIMO (M-MIMO) technology that is currently permeating the rollout of 5G. Interestingly, the large body of theoretical results derived for M-MIMO over the last decade can be recast in the CF-M-MIMO framework yet the distributed nature of the system needs to be carefully factored in. This paper aims at highlighting the different trade-offs affecting various performance metrics in CF-M-MIMO networks. In particular, the influence and consequences of using different precoding strategies, various power allocation techniques and pilot allocation strategies will be discussed and assessed. Moreover, a novel technique, termed user-subset selection, is shown to significantly improve the performance of maxmin power allocation at the cost of penalty in the form of an outage probability.

ABSTRACT. WSNs are characterized by lossy wireless links and severely resource constrained nodes in terms of energy availability and computation capability. Among the resource constraints, energy is probably the most crucial one since sensor nodes are typically battery powered, which limits the operating time of the sensor network. Hence, energy efficiency plays a major role in the design of wireless sense network protocols. In many of these networks, RF operations are sensors’ highest energy-consuming task, and thus, any potential waste must be minimized. In this paper, we discuss how adjusting the node transmission power (PTX) allows them to comply with energy constraints without impacting quality of service, based on experimental data. We show that PTX has a strong impact (near to 20%) on both the energy consumed by the nodes and the quality/reliability of the communication links. Finally, we propose a methodology to optimize PTX according to link quality metric by taking advantage of the physical energy consumption behaviour analysis.

ABSTRACT. Prolate spheroidal wave functions (PSWF) are a temporally orthogonal set of waveforms in which energy is concentrated in a finite time window and finite bandwidth. In wireless communications, where binary information is encoded onto a sequence of pulses, individual symbols can conceivably be represented by different orders of PSWF pulse shapes for transmission. Because these pulses have approximately constant bandwidth and pulsewidth across all orders, they are an interesting alternative to conventional modulation formats. Although they are certainly capable of improving spectral efficiency and data capacity, in this study we investigate their feasibility in achieving physical-layer security in wireless RF transmissions.

ABSTRACT. In the literature, wireless powered communication networks (WPCNs) are typically assumed to employ dynamic time division multiple access (TDMA), such that the rate and duration for information transmission of each energy harvesting user (EHU) is adjusted in each TDMA frame. Such implementations are fairly complex, so, in this paper, we propose a simple model for a WPCN employing a static TDMA, where each EHU employs fixed rate transmission over fixed time slot duration. Specifically, we develop a simple communication scheme that maximizes the network throughput by proper selection of the duration of the radio frequency energy broadcasts by the base station (BS), and the optimal information rate and optimal transmission duration of each EHU. The performance of such system depends only on the average gains of the channels between the BS and each EHU, which can be estimated more cost effectively than the instantaneous channel state information.

ABSTRACT. In this paper, we present normalized channel capacity of Free Space Optical (FSO) communication link, which is obtained by using power and rate adaptation technique. The presented results for capacity are obtained when the channel is modeled by Malaga model of atmospheric turbulence (for integer values of beta parameter) with pointing error. Impact of arbitrary selected cut-off signal-to-noise (SNR) level on average power is considered. Also, impacts of average power and arbitrary selected cut-off SNR level on channel capacity are considered. Analytical closed form expression for average power versus arbitrary selected cut-off SNR level for different values of received SNR is given. Expression for normalized channel capacity which is obtained by using power and rate adaptation technique is given. Obtained results are numerically calculated and graphically presented for different values of arbitrary selected cut-off SNR level.