Electromagnetic modeling of a lightning rod

The paper deals with a simple model for an assessment of the current density induced in the human body located in the vicinity of a lightning rod struck by lightning due to an electric field irradiated by the rod. The lightning rod is represented by a straight thin wire antenna excited by an equivalent current source. The current induced along a lightning rod due to a direct lightning strike is determined by solving the homogeneous integro-differential equation of the Pocklington type. The knowledge of the current distribution along the rod provides the calculation of the related irradiated electric field. The corresponding Pocklington equation and field integral relationships are handled via the Galerkin-Bubnov scheme of the Indirect Boundary Element Method (GB-IBEM). The human body is represented by the symplified cylindrical body model governed by the Pocklington equation for thick wires which is handled numerically via GB-IBEM.

A metal-only reflectarray (MOR) antenna for 77 [GHz] was analyzed with the equivalent surface current sources. The equivalent current sources can be used to produce the incident fields radiated from a feed. When a feed is an open-ended rectangular waveguide (OERW), the calculated antenna gains for the equivalent current sources, point source, and CST Microwave Studio (MWS) are 31.8, 30.0, and 31.6 [dBi], respectively. The simulated results of the equivalent current sources and CST MWS are in good agreement with each other in terms of the antenna gain.

The paper deals with an analysis of curved wire antennas. The formulation is based on the Pocklington integro-differential equations for curved wires which is solved via the Galerkin-Bubnov scheme of the Indirect Boundary Element method (GB-IBEM). Some illustrative computational examples related to thin wire loop antenna and various helical antenna types are given in the paper.

The paper deals with a transient analysis of a finite length wire embedded in a dielectric half-space and illuminated by the electromagnetic pulse (EMP) using a simplified reflection coefficient approach. A direct time domain formulation is based on the wire antenna theory and on the corresponding Hallen integral equation for half-space problems. The presence of a dielectric half-space is taken into account via the simplified reflection/transmission coefficient arising from the modified image theory. The Hallen equation is solved via the time-domain Galerkin-Bubnov scheme of the Indirect Boundary Element Method (GB-IBEM) and some illustrative numerical results are presented. The transient response obtained using the simplified reflection/transmission coefficient approach is compared to the results obtained via the Fresnel coefficients approach.

According Teslapsilas idea his magnifying transmitter has been designed not only to efficiently emit Hertzian waves, but also to transmit power at large distances. Analysis of Teslapsilas transmitter by using the wire antenna theory and reflection coefficient approximation is carried out in this work. The radiating part of the Teslapsilas transmitter is represented by an equivalent monopole antenna driven by an ideal current source thus replacing the Teslapsilas transformer. The frequency domain formulation is based on a homogeneous Pocklington integro-differential equation. The ground effects are taken into account via the corresponding reflection coefficient appearing within the integral equation kernel. Solving the Pocklington equation via the Galerkin Bubnov variant of the Indirect Boundary Element Method (GB-IBEM) the current distribution along the monopole antenna is assessed. Knowing the current distribution along the vertical monopole the radiated electric field is obtained by integrating the induced current. Numerical results for the monopole current and the related irradiated field are presented in the paper. The case studies of free space, perfect ground and imperfectly conducting half-space have been considered. This paper should be regarded as an extension of the previous work on the subject.

A method for allocating var support based on branch's complex power components is presented. First it is pointed out that source's active power and load's complex power should be responsible for var support based on analysis. Then each of source's active power and load's complex power is modeled by its equivalent nodal injection current sources based on reactive optimal power flow (OPF) solution. Each of source's reactive power used for var support is modeled by a shunt reactance called cost reactance. Finally, the nonlinear relationship between resistance and equivalent injection current sources is established based on the algorithm of branch's complex power components. As a result, var support of each reactance is accurately allocated between source's active power and load's complex power. The proposed method is of the following properties by comparison with the existing methods: The var support of a power system is always recovered; It is applicable for any transmission systems of looped configurations and loop flows; It needs no any assumption and simplification, and takes into account the interaction between active and reactive power; The proposed method gives a completely novel and analytical way of allocating var support cost. Simulation results of different power networks show that the proposed method is effective.

This paper proposes an extension of Finite Element Time Domain (FETD) method for the global electromagnetic analysis of complex active microwave circuits. The equivalent current sources and capacitances of the distributed part of the circuit, derived from FETD analysis, are incorporated into state equations to solve the lumped element part of the circuit. Benchmark tests on a microwave amplifier and self-oscillating mixer indicate that this extended FETD is not only superior in mesh flexibility but also gives much better results than a simulated FDTD-based algorithm.

This paper presents a layout optimization method for maximizing the torque-to-weight ratio of an electromagnetic actuator. Layout optimization, which focuses on finding practical designs to maximize output performance in a compact design, avoids nonlinearity and local convergence problems in the optimization of the electromagnetic system using two sequential steps; linear topology optimization and integer programming. Formulated in terms of decomposed volume and surface elements with equivalent current sources, the linear topology optimization optimizes the permanent magnet material distribution in the rotor. With the linearly optimized designs, integer programming determines the “most preferred” design in the second step by evaluating performances over design complexity. As illustrations, the method is applied to maximize the torque performance of two different three-phase disk-shaped synchronous motors. The effects of two different current waveforms, sinusoidal and square wave, on the torque magnitude and ripple are considered in the optimization. The design method has been experimentally validated by comparing simulated results of the layout optimization with measured magnetic field and torque output. This component-wise method that maximizes the net force/torque averaged over various orientations represents an improvement over existing algorithms where topology optimization is conducted at a specific rotor orientation to reduce the computational cost.

A method which improves ease and accuracy of calculation of the resistivity correction factor (RCF) is described. The method applied for the system consists of a circular semiconductor and a four-probe array. The method of images is introduced to obtain the RCF. The equivalent current source and sink for circular current probes are derived by taking into account the image current probes as well as the actual current probes. Numerical evaluations show that for thicker samples the calculation of the RCF is speeded up, and decrease in the RCF due to the image current probes becomes remarkable in the vicinity of the sample edge.

A hybrid full-wave electromagnetic (EM) field-circuit simulation method, which aims at accurately analyzing microwave circuits, is proposed. This method adopts the finite-difference time-domain (FDTD) algorithm for the EM simulation, the sophisticated equivalent models in a general circuit simulator SPICE for the circuit simulation, and hybridizes the FDTD and SPICE by using the equivalent current source (ECS) approach. Moreover, three techniques, which map a lumped circuit into FDTD cells as a wire, surface or volume structure respectively, are thoroughly studied. The formulae of the ECS with these three techniques are derived and introduced in detail, and their influences on the simulation accuracy are analyzed. The proposed method is applied to two sample circuits, a microstrip line and a frequency selective surface (FSS), both of which are loaded with diode pairs. The simulation results are compared with the measurement ones, and good agreement is observed, indicating the accuracy and versatility of the method.

Optimal parameter design of input filters for general purpose inverter based on genetic algorithm

This paper studies the D-STATCOM allocation problem to mitigate the voltage fluctuation on the distribution system and the effect of the distributed generation on the proper location and the economical size. The mathematical formulation of the problem is presented. The loads and D-STATCOM are modeled by their equivalent current sources. The power electronic based distributed generators are used to mitigate the voltage fluctuation, therefore the effect of those distributed generators on the allocation problem are studied as well.

We consider in this paper the derivation of input equivalent noise voltages and currents for both feedback and nonfeedback amplifier configurations. In the case of feedback amplifiers, a greatly simplified, approximate analysis is utilised and the accuracy of the approximation established. For low-noise amplifiers, a systematic design approach based on input equivalent noise sources is outlined. The relationship between the dual-input equivalent noise voltage and current sources is also established and a design example presented.

Common mode electronic noise in differential circuits

A myelinated nerve fiber is modeled as a straight thin wire antenna and stimulated by a current generator at the fiber beginning. The model is based on the corresponding homogenous Pocklington integro-differential equation for the perfectly conducting wire in a lossy unbounded homogenous space, where the activated node of Ranvier is modeled as a thin wire junction with an additional current source. The additional current source represents the ionic current of the activated Ranvier's node. The intracellular current results are obtained for the nerve fibers of two different diameters, stimulated by different rectangular pulses. The thresholds are determined by related strength-duration curves.