A genetic algorithm based method for modeling equivalent emission sources of printed circuits from near-field measurements

Abstract

A method for modeling electromagnetic emissions from printed circuits with equivalent dipole sources is presented. An optimization procedure based on the genetic algorithm is used to determine the number of equivalent dipoles and their parameters by fitting to the measured near fields. Prediction of emissions from the PCB can then be obtained by computing from the equivalent model without reference to the details of the PCB. I. INTRODUCTIONThe effects of electromagnetic emissions from printed circuit boards (PCBs) with fast clock are becoming an important topic in the design of electronic devices. The issues of electromagnetic compatibility (EMC) of PCBs include not only predicting the far fields, but also identifying the primary radiating sources. Therefore, the idea of representing a PCB with a set of equivalent currents or dipoles is attractive because of its simplicity. An infinitesimal dipole is the simplest radiator which can be plugged and played in any electromagnetic package, thus modeling with equivalent dipole sources dramatically reduces the complexity of modeling emissions from a complete PCB.For most approaches, the equivalent source is deduced from the measured near-field distribution as near-field measurement has advantages in high accuracy and reliability. In [1, 2], an antenna is represented by equivalent magnetic or electric currents over a fictitious plane, and the sources are determined from both magnitude and phase information of near-field data by an electric field integral equation. The use of equivalent magnetic currents was extended to the level of printed antennas in [3]. It is also reported that the far field is determined from only the near-field amplitude over two surfaces with a phase retrieval algorithm [4]. Finally, in our previous work [5], an equivalent dipole model is discussed which replaces a PCB with an array of equivalent magnetic dipoles placed in a pre-fixed grid on a 2D surface. The dipoles are determined by directly fitting the scanned near-field data.In this paper, an alternative method is presented for equivalent source identification of PCBs. The PCB is represented by an array of magnetic dipoles found from an optimization procedure using the genetic algorithms based on near-field scans. Radiations from the PCB can then be obtained directly from the equivalent dipole model. The proposed model retains the advantages of computational simplicity and accuracy. Furthermore, the number of dipoles

A Particle Swarm Optimization-Based Approach for Predicting Maximum Radiated Emission From PCBs With Dominant Radiators

“…Thus, it is preferable if the equivalent sources can be reconstructed with amplitude-only information. For this, a genetic algorithm was introduced to find the optimal dipoles to represent radiated emission from a PCB in [11] and [12]. The resulting methods do not need phase information; however, they are associated with a very heavy computational burden.…”

“…The resulting methods do not need phase information; however, they are associated with a very heavy computational burden. The computational times for a single frequency are, respectively, four and five hours with the given example in [11] and [12]. Therefore, it can be anticipated that, with an increasing complexity of PCB structures, there will be more computational challenges one has to overcome to accurately quantify the equivalent dipoles.…”

An efficient hybrid hot-spotting and optimization method for radiated emission compliance check

“…Inspired by its efficiency and flexibility, near-field scanning is further extended to predict the far-field radiated emissions for EMC assessment by modelling the PCBs with equivalent dipoles [2]- [5]. In [2] [3], the PCB is modelled by a set of elemental dipoles with fixed number and position, and a local optimization method is introduced to determine the moment components of each dipole.…”

“…They are accurate, however huge computational resources are required. Approximately 4hours and 5hours are respectively taken to retrieve the equivalent dipoles with the given example in [4] and [5] for a single frequency simulation. As the working frequency and structure complexity increase, more computational challenges will be imposed to accurately quantify the equivalent dipoles.…”

Two methods for transmission line simulation model creation based on time domain measurements

“…This can be used to solve an inverse problem and to identify the equivalent sources of the planar structure. This approach is discussed in ; Baudry et al (2008); ; and Tong et al (2010). Several methods dealing with the inverse problem are ill-posed due to the presence of errors in measurement data, or suffer from the problem of converging to local minima.…”