We present and discuss the parallel implementation on GPUs of three types of NUFFTs in CUDA language: NER (Non-Equispaced Results), or type-1, NUFFTs dealing with equally spaced samples and returning non-equally spaced results; NED (Non-Equispaced Data), or type-2, NUFFTs dealing with non-equally spaced samples and returning equally spaced results; Type-3 NUFFTs, dealing with non-equally spaced samples and returning non-equally spaced results.The computational and accuracy performance of the three implementations are analyzed for the three cases with reference to array antenna radiation problems. In particular, the timing performance is assessed against that of a parallel implementation of the same algorithm on multicore CPUs.
It is well-known that the main drawback of nonFoster elements is their inherent proneness to instability. Although recent introduction of a band-pass non-Foster negative capacitor softened stability problem considerably, appropriate real-word applications are yet to be seen. To this end, a possible use of a band-pass non-Foster negative capacitor in impedance inverter is investigated. Preliminary analytical and numerical results show that is possible to construct a stable impedance inverter with a multi-octave bandwidth.
We previously reported the simulation results of the RG405-based open-ended coaxial probe model for biological tissue sensing depth analysis. The simulation model with this specific geometry proved valid for calculating the probe perceived permittivity at 2 GHz, triggering a follow-up study on the impact of the probe size on its permittivity sensing depth. In this study, the probe dimensions were upscaled up to five times, while keeping the same relative geometry to maintain the 50 Ω coaxial line impedance. The permittivity sensing depth was again analyzed on both the non-biological water-Teflon model, and biological layered tissue model. The results clearly showed the increased permittivity sensing depth of the larger probes with respect to the smaller ones, at 2 GHz. Nevertheless, the surface layer of the analyzed non-homogeneous samples was the dominant one for all probe sizes.
The Green’s functions of layered structures are used for analysis of measurement errors of transmitting losses through homogeneous and sandwich-type antenna radomes. Influence the spherical waves excited by radiators in the near zone is under investigation. As the simplest antenna, the Hertz dipole was used for calculations. The model of equivalent electric circuits was used for layered structure modelling. The transmitting losses of electromagnetic waves versus frequency for different dielectric sheets are shown. Influence of the distance between antennas on the transmitting loss measurements is analyzed.
Inherent dielectric properties discrepancy between different tissues have long been of interest to researchers in order to improve medical diagnostic approaches and therapeutic technologies. Hence, determination of the dielectric properties for biological tissues is keystone to develop an innovative medical system. Widely, the dielectric properties of biological tissues have been determined by utilizing slim form open-ended probes. Although, the method is superior to other dielectric property measurement techniques in several aspects, the measurement procedure suffers from equipment-related and tissue-related errors. Sensing depth, which is one of the confounders can be associated with both equipment and tissue-related errors. In this work, we performed the preparation of skin mimicking phantom and conducted a series of experiments on a two-layer configuration consisting of the prepared phantom and a liquid (olive oil). Furthermore, the sensing depth of the 2.2mm aperture open-ended coaxial probe was analyzed at five different frequencies. The results obtained show that the sensing depth of biological tissues strongly depends on the operation frequency. We also observed that the sensing depth decreases at higher frequencies and this is a property can be utilized in tackling thin multi-layered structures problem such as skin cancer detection.
The synthesis of a shaped beams by means of given fixed-geometry arrays is a canonical open problem relevant in many engineering areas. In fact, several approaches have been proposed for optimizing as much as possible some performance parameters or the dimensions of the arrays, but they all suffer from several drawbacks which are effectively tackled by the proposed approach. In this contribution, we propose an innovative approach to the mask-constrained power synthesis of shaped beams through fixed-geometry antenna arrays having whatever layout and element patterns. In particular, we are able to formulate the problem as the global optimization of a very small number of parameters, and we propose and discuss two different solution procedures.
The paper deals with analytical calculation of spectra integrals of HF signals which can be regarded as measures for quantifying the human exposure to signals with continuous spectra. Signals generated by Digital Audio Broadcasting (DAB) are of interest. An approach based on the well-established expressions stemming from the signal theory, where integrals of radiated field spectra are calculated from the measured field amplitudes, is used. A computational example dealing with measured DAB spectra is presented.
This paper aims to present descriptions, principles, and results of the educational activities carried out in COST (European Cooperation in Science and Technology) Action TU1208 “Civil engineering applications of Ground Penetrating Radar” (2013-2017). The Action was especially active in the organization of training schools (TSs), which focused on all aspects of ground penetrating radar (GPR) technology, methodology, and applications; overall, 15 TSs were organized in eight countries of the European continent, attended by more than 430 trainees. The Action also organized a successful series of science communication activities to establish a dialogue with stakeholders and end-users of GPR research, as well as to increase public awareness about GPR capabilities and applications. Most science communication activities were carried out in less research-intensive countries of the European continent and the overall initiative was denominated “TU1208 GPR Roadshow.” Part of the Roadshow consisted of a series of non-scientific workshops and practical demonstrations held in six countries and attended by more than 480 participants; in parallel, a series of initiatives with children and citizens were carried out in Estonia. Two more educational initiatives of COST Action TU1208 are presented in this paper. In particular, the Action developed an open-access educational package (“TU1208 Education Pack”) for teaching GPR in University courses. Moreover, the Action developed and made available an openaccess guide for building a cheap frequency-modulated continuous-wave GPR prototype, conceived for training purposes.
This paper presents the development of a 24GHz radar front-end for monitoring babyies and newborn inside a cot. The signal processing used is a straight forward approach to simply verify the functionality of the hardware system. First test measurements are shown.
This paper propose a method based on variational Born iterative method to solve the inverse scattering problem of three-dimensional objects buried into two-part space. The addressed problem is substantially complex in both mathematical and computational aspect, because of the fact that the objects to be reconstructed are both three-dimensional and embedded into half-space. Variation born iterative method (VBIM) is as successful as distorted born iterative method (DBIM) that is the most widely used method in the reconstruction of high-contrast objects among Born-based methods. Furthermore, VBIM is much faster than DBIM because it doesn’t require a forward problem solution for the calculation of background Green’s function in every iteration step, such as DBIM. Various numerical implementations have been performed to reveal the effectiveness of the method and it is observed that the method is very successful in the reconstruction of multiple objects with arbitrary geometry.
Vibrations and their parameters can be measured through monitoring the speckle pattern of multimode optical fiber. In this paper a modified approach to realization of a specklegram based vibration sensor system is discussed. Replacing the (standard) camera detector with an array of several detector diodes improves the size and frequency range of the system. Different statistical methods for processing the signals from the diode array are presented, compared experimentally and discussed. The principal advantages of the specklegram vibration detection approach, low cost and distributed detection possibility, have been retained.
When divers rescue people who have accidents at sea, they are in danger because of parts of obstacles floating in the sea. If they can confirm their own positions, their activities will become much safer. In this study, assuming we specify the positions of the divers rescuing in the accidents and support their works, we investigate undersea positioning technology using the electromagnetic waves with low frequencies less than midrange waves. In some preceding studies, an ultra-long wave of 10 kHz theoretically attenuates 3.5 dB per meter [1]. In addition, the simulation of the position estimation in the vertical section of the sea has already reported. In this report, we indicated the superiority of using Receiving Signal Strength: RSS to the phase difference between a transmitted signal and the received one. We also showed the result of the position estimation of the transmitting antenna at depth from 2 m to 8 m.
A new approach for the rigorous design of reflectarray antennas is presented. Traditionally, reflectarray antennas are designed assuming local periodicity in which the mutual coupling is modeled as though each element is embedded in an infinite array of identical elements. This allows the fields to be expanded in terms of a Floquet series expansion. The design approach is approximate since reflectarrays are in fact aperiodic. Here, we present a new design approach which avoids any local periodicity assumption. Each element is modeled as a distinct element, and coupling calculated for the true array. Thus, the approach is rigorous. Simulation results are presented that verify the design method.
Intentional electromagnetic interference is a potential issue for railway networks based on ground-to-train communications. Reported mitigation techniques usually rely on electromagnetic compatibility classical procedures, which are not always the best option for such an unpredictable event. In this work, offline adaptive filtering is used to recover global system for mobile communications - railway damaged data.
With increasing radar activities in the automotive, industrial and private sector, there is a need to test radar sensors in their environment. A radar target simulator can help testing radar systems repeatably. In this paper, the authors present a concept of low-cost hardware for radar target simulation. The theoretical foundations are derived and analyzed, and a possibility to simulate the Doppler effect correctly by using a CORDIC algorithm in VHDL is shown by using a FPGA to do a rotation of the I/Q baseband signals.
The Singular Value optimization method has been successfully applied in the framework of the Near-Field antenna characterization. This approach provides a drastic reduction of the number of measurement points and of the measurement time with respect to standard and non-standard techniques. Here an analysis of the sensitivity of the method with respect to the noise is performed.
In this paper a novel idea of estimating the 3D geometry and building material of indoor environments is proposed. The idea is based on assumption that the received radio signal is distorted due to interaction with the surrounding objects and thus includes the signature of the radio environment. We describe the methodology how to apply radio environment signatures for characterization of geometry and building material of indoor environments applying machine learning tools using ray tracing simulations and ultra-wide band communication technology. The idea is based on the assumption that the emerging broadband wireless systems applies multiple antenna and is able to estimate the channel impulse response for each transmit-receive antenna pair.
Ageing of population will increase the number of people demanding the assistance and medical support. In order to increase the life quality of elderly people the medical support and assistance will be provided at people homes which require the development of new technologies to support their living and reduce needed interaction of the nursing stuff. Activity detection and deviation from daily activity patterns are recognized as the main indicators to identify modification of the people behaviour showing potential risk in the deterioration of their physical and mental health. The passive and active localization are two key technologies applied for activity detection and tracking. In this respect in this paper we specify a new communication protocol for passive and active localization applicable for assisted living applications supporting tracking one person in their apartment. Communication protocol exploits the IEEE 802.15.4-2011 UWB communication technology for ranging and channel sounding application as inputs for the passive and active localizations.
A system for location estimation based on information about visible base stations on mobile device is presented. The system consists of a web application with a database and a mobile android application that communicate with each other via REST APIs. In the system, two primary functionalities can be activated depending on the availability of global navigation system information on a mobile device. In the case of availability, information about the mobile device, its location, altitude, time and visible base stations are stored in the web application database. In the case of inaccessibility of the global navigation system information, the mobile application sends to a web application the location query based on information about the visible base stations on the mobile device and obtains location estimate. Within the web application, a location estimation algorithm and data validity management algorithm are carried out. During preliminary experimental period of data gathering in one urban and one suburban environment, the performance evaluation was carried out and the system showed good initial performance. The benefit to all potential target industries and challenges of presented system are given.
The recently proposed near-field/far-field (NF/FF) transformation technique with spherical spiral scan, which, by properly exploiting the non-redundant representations of electromagnetic fields and the unified theory of spiral scans for non-volumetric antennas under test (AUTs), allows one to properly account for a mounting of an elongated AUT in offset configuration, is here experimentally validated. It is based on the prolate spheroidal source modelling and requires the same number of NF data as in the case of an onset AUT mounting, depending such a number only on the surface of the adopted AUT modelling. Moreover, it makes use of an efficient 2-D optimal sampling interpolation formula to recover the NF data needed to perform the standard NF/FF transformation, whose amount is related to the radius of the minimum sphere enclosing the AUT and centred at the scanning sphere centre. As it will be shown, the experimental results will further confirm the practical effectiveness of the proposed technique.
