Electromagnetic and circuit modelling of a modified design of bulk current injection probe calibration jig

In this study, a wideband rounded-shield calibration fixture or jig used to calibrate in-band injection probe is implemented based on 3D electromagnetic modelling in CST Microwave Studio; the Electromagnetic (EM) model is validated and then used in studying the effect of the jig layout parameters on its bandwidth. The impact of a rounded instead of the typical flat shield is studied too, and showed an improvement of about 15% in the bandwidth at Voltage Standing Wave Ratio (VSWR) level of 3. A new systematic rules procedure for extracting the circuit model of transmission lines based structures is proposed and applied in deriving a circuital model for the jig. The EM and developed circuital models are validated versus vectorial scattering parameters and VSWR. The estimation of the uncertainty shows small values at the band of measurement. The developed prototype meets DO-160 and MIL-STD-461E requirements and shows an improved high frequency performance when compared with reliable products. An application is presented in measuring the insertion loss of bulk current injection probe and in illustrating the effect of the shield slot distance on the probe High Frequency (HF) performance.