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 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 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 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.

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.

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.

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.