Shinji Fukui

An estimation method for the n port S parameters with n-1 port measurements

An estimation method of the three-port S-parameters for reciprocal circuits is presented. In this method, several known loads are connected to two of the ports and reflection characteristic of the remaining port is measured. Therefore, there is no need to connect network analyzer to the ports which are connected to the known loads. S-parameters are obtained by solving a linear system equations and quadratic equations only. In addition, a method for determining the port voltages from the estimated S parameters is also described, Then applying this method to estimate the S-parameters of an immunity test system, validness of this method has been confirmed. The proposed method will be applied when there is no common ground between each ports.An estimation method of the n-port S-parameters for reciprocal circuits is presented. In this method, several known loads are connected to one port in turn and reflection and transmission characteristics among the remaining ports are measured. Therefore, there is no need to connect a network analyzer to the port that is connected to the known loads. S-parameters are obtained by solving a linear least-squares equation and a quadratic equation only. In addition, applying this method to estimate the S-parameters of an immunity test system, validness of this method is confirmed.

Empirical estimation of probability distribution for electric field strength in automotive cabin

A novel model of the probability distribution for electric field strength in automotive cabin is proposed in the form of a mixture distribution of a linear Rayleigh distribution for low-value data and a log generalized extreme value (GEV) distribution for high-value data. A sample model is estimated from the data measured in a horizontal two-dimensional area above main battery in a hybrid vehicle. For the probability distribution model of the ensemble data of different transmitter antenna directions and all target frequencies, the mixture weights and the parameters for each component distribution are estimated using expectation-maximization (EM) algorithm. The result model showed good fitting to the measured data in probability density function plot and quantile-quantile (Q-Q) plot. Based on the ensemble data distribution model, the probability distribution models for individual conditions of frequencies and antenna-directions are also estimated applying linear transformation. Results are tested using Q-Q plot, which shows good fitting with slight overestimation in very high-value region. Kolmogorov-Smirnov (K-S) goodness of fit test at the 1% significance level also accepts this method for all the data measured above 600MHz.

An improved estimation method of 4 port S-parameters with 2 port measurements

An estimation method for the S-parameters of 4-port connection circuit connecting a 2-port device to its one end is presented with a novel algorithm to improve the estimation accuracy. The 4-port S-parameters for the connection circuit are estimated using indirect measurements where several known loads are connected to the 2 ports at the far end of the connection circuit, where a 2-port device is to be connected, in turn and the reflection and transmission characteristics among the near end 2 ports of the connection circuit are measured. The estimation method is constructed in the framework of linear algebra that eliminates the needs to solve nonlinear equations numerically, which also enables application of theoretical analysis to this method. This method can be applied to obtain the S-parameters of the 2-port device connected at the far end of the connection circuit by de-embedding the estimated 4-port connection S-parameters.

Mathematics of 2r-port S-parameter Estimation by the r-port measurements

An estimation method of the 2r-port S-parameters for reciprocal circuits is presented. In this method, several known loads are connected to r ports in turn and reflection and transmission characteristics among the remaining r ports are measured. Therefore, there is no need to connect a network analyzer to the ports that are connected to the known loads. S-parameters are obtained by solving several linear equations and quadratic equations only. In addition, applying this method to estimate the S-parameters of an circuit model of an enclosure mounting an IC chip, validness of this method is confirmed.

Analysis of electromagnetic wave propagation by using Poynting vector in automobile

Conventional methods used to clarify electromagnetic noise propagation in a vehicle have mainly concentrated on the measurement of electric and magnetic fields, but if we measure the way in which the electromagnetic energy is being transmitted from the source, this will make it possible to take more effective action against such electromagnetic noise. This paper describes a method using a tri-axial magnetic probe in the vehicle to detect the near magnetic field, whereupon the electric field is obtained by calculating it from the magnetic field and from this, the Poynting vector, which indicates energy flow, is calculated. Using this method, it is possible to visualize the energy flow of electromagnetic wave generated by antennas in the vicinity of the vehicle and electromagnetic noise generated from the vehicle.