Evaluation of the tubular wave coupler model parameters for setups involving wires

In a previous work, a model based on multi-conductor transmission line (MTL) theory was developed for the setup involving a tubular wave coupler (TWC) mounted in the calibration-jig. To account for the non-uniform distribution of currents and charges on the TWC metallic frames, the model parameters were estimated by resorting to an optimization procedure aimed at fitting the S-parameters measured at the ports of the calibration fixture. In view of extension of the proposed model to complex wiring harnesses, this work investigates the possibility to exploit such an MTL model to predict RF current injection onto wiring structures with geometrical/electrical characteristics different from those of the calibration fixture, without the need for re-optimizing the involved p.u.l. parameters. To this end, two parameters are identified as responsible for TWC-to-cable coupling, and specific analytical expressions and/or 2D electrostatic simulation are suggested to adapt/tune these parameters to the characteristics of the new wiring structure the TWC is clamped on. Feasibility of such an approach is assessed by comparison versus numerical simulation of an electromagnetic model of the TWC mounted on different wiring structures.