Abstract This article describes the use of a low-cost softwaredefined radio applied to an Electromagnetic Compatibility (EMC) test. The proposed system is indicated for cases when an autonomous instrument is better suited, i.e., when there is no need for external signal or power connections. As a proof of concept, a metallic cavity has its shielding parameter measured, and the obtained results illustrate the kind of outputs the instrument can provide. Details concerning the hardware and software utilized are mentioned, alongside observed pitfalls and trade-offs. It is an affordable and versatile method, which can replace the traditional use of spectrum analyzers and receivers, especially in precompliance tasks. lowcost low cost EMC (EMC test suited ie i e i.e. connections concept measured provide mentioned tradeoffs. tradeoffs trade offs. offs trade-offs method receivers tasks i.e

This article explores the magnetic field sensor embedded in mobile phones, and presents some ways to use it together with straightforward software applications. Measurements are processed with features such as averages, georeferencing coordinates, data exporting, visualization, etc, by means of an open-source tool. Covering the hardware part, the sensor magnitude calibration and also its frequency response are discussed. All materials and elements are affordable and easily available. Results show the high potential of its use in class and also for research applications. phones applications averages coordinates exporting visualization etc opensource open source tool part discussed available

Concerns regarding long-term effects of stray electromagnetic fields emitted by household appliances have been usually covered by mainstream and social media outlets, even though biomedical exposure studies have conclusions leaning towards low-risks. The quick deployment of Internet of Things (IoT) shows that the number of connected devices is likely to increase even more. Though most systems operate with very low-amplitude field levels, the coexistence of several different devices and continuous operation near the human body is seen as a possible cause of illnesses, particularly in children. This study shows a method of addressing fields at the 2450-MHz range using low-cost and easily constructed devices, based on a software-defined radio operating as a receiver. It allows the investigation of hot spots inside residential or office areas, with measured amplitude field levels found after proper conversion using the sensor antenna factor.

Abstract A low-cost spectrum analyzer is presented, based on a commercial software defined radio and an open-source application package. Fundamentals regarding the receiving operation and its sensitivity are presented, along with measurements, of two 8 and 12-bits software defined radio models. An application, run within GNU Radio, is presented, deployed to overcome the hardware analog-to-digital converter limitation to monitor wide bandwidths. Results are shown for two different frequency ranges, 200 MHz bandwidth.

Abstract Monopulse radars operate with simultaneous beams and are used for tracking purposes, relying only on hardware to provide a real-time indication of the target position. A monopulse array and its feeding network is implemented and tested, in the frequency of 5.4 GHz, based on patch antennas using dieletric to provide wide bandwidth and high gain. The system field styrofoam as pattern was evaluated in two different environments, a shielded room and an indoor area. Results agreed with simulation for either individual elements as well as the final integrated monopulse array.

Abstract A transistor avalanche noise generator (TANG) is described. It is based on an off-the-shelf RF transistor with an integrated planar monopole. From a 70 V DC power it generates sub-nanosecond pulses with amplitudes close to 1 V. The proposed solution does not employ step recovery diodes, and it is based as the name implies on the operation of a bipolar transistor crossing into the avalanche region. Radiation measurements showed energies close to −40 dBm at frequencies near 600 MHz, with energies reaching the range of 1 GHz.

Abstract This paper introduces the Characteristic Mode Analysis in the computation of electromagnetic resonant modes in conducting bodies. Canonical cases (thin wire and a rectangular plate) are analyzed, along with real-world complex structures, a mobile phone chassis and an unmanned aerial vehicle. Given the analogy to other areas, such as modal analysis in Differential Equations, this method can be another tool when teaching Electromagnetic Radiation and antenna related topics.

ABSTRACT: This article presents a hybrid computational method to address the datalink characteristics of an Unmanned Aerial Vehicle (UAV) relay. It uses the 3D far-field gain data from the antennas (UAV and ground station), separately computed or based on available measurements as inputs, and then applies the 2-Ray propagation model, taking into consideration the ground permittivity and the respective antenna heights. By doing so, different numerical approaches cover the two different physical scales. Since the installed antennas (i.e. antennas considered placed on the UAV fuselage) performances are considered, a higher reliability can be achieved with the covered procedure, at lower costs when compared to field measurements. Results for different example scenarios are presented and discussed.

Abstract: This article presents a set of measurements and simulations that evaluate the technical feasibility of a Compact Open Area Test Site (COATS), for the frequency range of 200 MHz to 2 GHz. Its main goal is to provide shielding effectiveness measurements. The described test setup is used for the tests in both semi anechoic chamber and COATS. These experimental and computational results offer orientations and guidelines about the best method to measure radiated emission in a COATS. These measurements results can be quantified through the Feature Selective Validation technique.

This article covers the design of an electromagnetic noise generator which uses an automotive coil as the main component. A short theoretical analysis covers the generation of high voltage pulsed current from the available DC source originated from the battery. An electronic dimmer, a circuit used to control the brightness of a light, by controlling the effective voltage that is delivered to the load, is used here to provide more degrees of freedom to the generated power as well as to insert higher order harmonics into the emitted electromagnetic spectrum. A prototype was built and its time domain current waveform is measured and shown, altogether with the measured radiated spectra, covering the frequency range from 20Hz to 1GHz. A broadband emission characteristics is verified, turning the use of common AM/FM radios impossible when close to the noise generator. A visible strong plasma is also seen due to the high generated voltages (around 60kV).

ABSTRACT The design, prototyping, and free-space measurement of a 6-GHz Frequency Selective Surface filter is presented. The prototyping resolution of a large (A4 sheet size) Frequency Selective Surface with small loops as elements is checked, as well as the correlation with measurements performed with a 3-D full-wave solver. The test also involved the effect of cascading two different Frequency Selective Surfaces with a viewpoint towards a narrower frequency range, which provided good results.

O artigo descreve a construção e modelagem simples de um protótipo de pequenas dimensões de um Coilgun – arma eletromagnética que dispara um projétil metálico cuja operação se assemelha aos motores elétricos lineares, que também acionam fechaduras magnéticas e atuadores. O projeto apresenta baixo custo, envolve construção com elementos facilmente encontráveis contudo envolve conceitos relativamente sofisticados de eletromagnetismo. O sistema pode ser empregado para estudos de física e também motores elétricos lineares, em Engenharia. O artigo discute modelos circuitais, análise da força magnética exercida no projétil e figuras do campo produzido a partir de um simulador eletromagnético. A instrumentação usada para medida da velocidade também é apresentada, com dados de medidas.

The article describes the construction and simplified analysis of a small-scale Coilgun prototype – electromagnetic weapon that launches a metallic slug whose operation is similar to linear electric motors, also seen in magnetic locks. The design can be constructed with low cost and easily available components, though it involves sophisticated electromagnetism concepts. The system can be employed to Laboratory experiments on Physics as well as on Engineering, to address Electromagnetic Conversion of Energy, namely linear electric motors and actuators. The article discusses circuit models, the electromagnetic force on the slug and also field plots generated from a commercial simulator. The used instrumentation for velocity measurement is also presented, alongside with measured data.

This work presents a new Ultra Wide Band (UWB) beamforming fifth-order derivative Gaussian pulse transmitter with dual small Vivaldi antennas for remote acquisition of vital signals in impulse radar applications. The system consists of a programmable delay circuit (PDC or τ), a UWB pulse generator (PG) circuit and an array of two Vivaldi planar antennas. The circuits is designed using the 0.18µm CMOS IBM process. Spice simulations show the pulse generation with 90mVpp amplitude and 300ps width. The average power consumption is 120µW per pulse, using a 2V power supply at a pulse repetition rate (PRR) of 100MHz. Full tridimensional electromagnetic simulations, using CST MWS, show the main lobe radiation with a gain of 5.5dB, and a beam steering between 20º and -17.5º for azimuthal (θ) angles at the center frequency of 7.5GHz.

Estruturas de onda lenta possuem aplicações em vários setores tais como aceleradores lineares, usados em aplicações médicas e em física nuclear; em válvulas eletrônicas e em filtros de micro-ondas. Uma compreensão adequada deste tópico requer conceitos de engenharia de micro-ondas, física e instrumentação, que são dificilmente cobertos em sua plenitude durante cursos de graduação. O artigo explora o tópico utilizando uma analogia com circuitos elétricos e também com o uso de um simulador tridimensional de campos eletromagnéticos. Um experimento em laboratório é sugerido de maneira a proporcionar uma atividade prática. A montagem de laboratório requer instrumentação comum em laboratórios de eletrônica e possui construção simples.

Slow wave structures have uses in several areas, as linear accelerators used for atomic studies and in medical applications, vacuum tubes and as microwave filters. An adequate understanding of this topic requires knowledge on microwave engineering, physics and instrumentation, which is hardly possible to be covered during normal physics or engineering undergraduate courses. This article aims to explore this topic using a circuit analogy and also a 3D electromagnetic field solver. A laboratory experiment is proposed to have a hands-on experience as well. The laboratory test requires common electronic instrumentation and it is easily constructed.

Abstract: The remote detection of a vehicle requires that some kinds of its emissions are tracked and detected. Usually, electromagnetic emissions are used in the form of radar (electromagnetic waves in the range of radiofrequency and microwaves). Different types of antennas are used as sensors, tailored to the signal frequency band and its polarization, as well as to the target distance (higher gain antennas used for low amplitude signals). For the specific case of radars, the use of computational methods to address the electromagnetic signature (spatial pattern of the scattered energy from the object) has become widespread, given the high costs and complex equipment associated with these respective measurements. Therefore, the use of computer simulation is ideally suited for creating a realistic database of targets and its respective signatures. The same computer-created signatures database can also be used for the thermal range, enabling a complete technology solution for the signature and design of stealth vehicles, with reduced emissions.