In this paper, we present a Transverse Electric (TE) polarized Bessel-beam antenna in the microwave range based on a leaky radial waveguide. According to the dispersion equation, an inductive sheet over a ground plane is needed. To achieve the inductive sheet, a grid structure printed on a dielectric substrate is designed. Besides, the radial waveguide is coaxially fed with a quasi-loop shaped structure to excite TE mode. The proposed antenna is investigated by simulation and measurement. In the measurement, a small loop is used to probe near magnetic field, and accurate measured magnetic intensity profiles are presented. The measurements show that TE-polarized Bessel beams can be launched within the non-diffractive range of 145 mm (2.803 λ0) at 5.8 GHz.

A novel rectifying circuit topology is proposed for converting electromagnetic pulse waves (PWs), that are collected by a wideband antenna, into dc voltage. The typical incident signal considered in this paper consists of 10-ns pulses modulated around 2.4 GHz with a repetition period of 100 ns. The proposed rectifying circuit topology comprises a double-current architecture with inductances that collect the energy during the pulse delivery as well as an output capacitance that maintains the dc output voltage between the pulses. Experimental results show that the efficiency of the rectifier reaches 64% for a mean available incident power of 4 dBm. Similar performances are achieved when a wideband antenna is combined with the rectifier in order to realize a rectenna. By increasing the repetition period of the incident PWs to 400 ns, the rectifier still operates with an efficiency of 52% for a mean available incident pulse power of -8 dBm. Finally, the proposed PW rectenna is tested for a wireless energy transmission application in a low-Q cavity. The time reversal technique is applied to focus PWs around the desired rectenna. Results show that the rectenna is still efficient when noisy PW is handled.

The characterization of conductive obstacles in subsoil is investigated in the induction regime. Validated by numerical experimentation, a simple model is proposed to calculate the main electromagnetic quantities of interest, the interaction between the obstacles being taken into account. The model is based on the extended Born approximation, the Lax-Foldy multiple diffraction theory, and introduction of equivalent spherical obstacles. Those are retrieved via a hybrid algorithm of differential evolution using a communication strategy between groups, which in particular enables separation of coupled obstacles close to one another.

This paper presents the design of a high-performance dual-band antenna for industrial, scientific, and medical (ISM) band applications. The proposed prototype consists of a low-cost patch antenna, 40 mm × 24 mm in size (i.e., 0.36λ₀ × 0.19λ₀, with λ₀ the wavelength corresponding to the low frequency), with a relatively wideband for both operational bands (up to 140 MHz at 2.45 GHz and 510 MHz at 5.8 GHz), and a radiation efficiency of over 90%. The antenna has a quasi-omnidirectional radiation pattern with gains of 2.41 dBi and 5.22 dBi at 2.45 GHz and 5.8 GHz, respectively. The design methodology is detailed and illustrated by simulation results showing the optimization steps and the characteristics associated with the antenna. Experimental results based on a fabricated prototype are presented and compared with simulation results from the design stage. Finally, the proposed antenna prototype is also compared with similar antennas available in the literature.

Fast and very fast transient overvoltages generally appear during switching operations within electrical substations. The oscillatory nature of such phenomena with frequencies that can reach several tens of megahertz tends to degrade the lifetime of high voltage equipment such as bushings and transformers, inducing partial discharges activity or breakdown of the insulation system. According to several case studies, bushings are one of the most sensitive parts to such overvoltages, indeed, a failure in a bushing will in most cases lead to a failure of the transformer, often catastrophically. Generating such overvoltages with a very high frequency character and considerable amplitude can be very difficult, moreover, studying the effect of such overvoltages on the insulated bushings is not easy, even experimentally. Therefore, a simulation of the fast transients in the system can be very useful to understand the consequences of such phenomena. In this context, this document aims to propose a model of high voltage capacitive graded oil impregnated paper (OIP) bushing based on a distributed electrical circuit. The equivalent circuit is constructed based on the geometric design and electrical properties of the materials. The model was developed and implemented using Matlab/Simulink® software, and was validated with experimental measurements based on impedance sweep frequency analysis. The modeling results are in a good agreement with the experimental ones.

The article presents an experimental platform, so called "RFID Waveformer," dedicated to the study of waveform optimization in the radio frequency identification (RFID) context. It is a flexible solution that enables waveform design and their energetic performance evaluation in a ultra high frequency (UHF) RFID link following the ISO-18000 GEN2 standard protocol. It consists of a reader emulated by a LabVIEW interface controlling radiofrequency laboratory instruments, which perform real time tag response detection. Its interconnection with MATLAB routines enables the design and the evaluation of arbitrarily shaped RFID waveforms. In this article, for illustration, three waveforms are tested with RFID Waveformer in a complex propagation environment: pulsed wave (PW) and time reversal (TR) modes compared to the traditional continuous wave (CW) mode. Experimental results show that both PW and TR modes improve the energetic efficiency of the forward link and so the RFID read range compared to CW mode. Furthermore, TR presents the optimal efficiency in complex propagation medium. The RFID Waveformer enables tag response detection in the three modes offering ease of use and repeatability of measurements. The RFID Waveformer being not limited to the scenario considered in this article, it is a versatile solution extendable to other contexts.