Identifying Reflections in High Frequency Structures

The goal of this work is to improve the modeling of Lumped Distributed Structures (LDSs) by obtaining a sensible aaccuracy with a reasonably low number of model parameters while identifying the reflections present.

First, a model suite consisting of three model classes with increasing complexity is introduced. The complexity of the models is chosen proportionally to the complexity of the LDS under study. A sum of delayed damped complex exponentials (Cisoids) is used to obtain initial values for the delays by simultaneous estimation of the delays caused by the structure’s transmission lines and the reflections imposed by the lumped elements.

This work provides an important contribution to the modelling and identification of LDSs while providing a model suite that can be applied to a wide range of applications.

Additionally, an adaptive sampling technique to shorten the time needed for a tuner calibration has been proposed. The adaptive technique allows for a strong reduction of the calibration time while keeping the accuracy at a high level. The proposed method decomposes the necessary 2D sampling of vertical and horizontal movements of the tuner probe into two 1D sampling and modeling procedures. It has been applied to the passive tuner and the different numerical results confirm the accuracy and efficiency of the proposed approach, and its potential for an adaptive and automated extraction measurement technique using adaptive excitation.

Schematic view

Figure : A general schematic diagram of the systems under study as a lumped/distributed structure. Transmission lines (TL) are tapped with the unknown elements or circuits (L). This example structure contains single and multiple reflection. The incident (a) and the reflected (b) are depicted. The case of the multiple reflection is illustrated by solid arrows while the single reflection case is depicted by dashed arrows.

Overview of the contributions

  • A model suite has been proposed that models LDSs. It consists of three models with different complexity that can provide accurate models and stay parsimonious in the number of model parameters [1].
  • A fully rational model (the Koga multi-delay model) has been implemented that can estimate multiple reflections with one set of parameters [2].
  • The model suite has been successfully applied to SI application examples [3].
  • An adaptive sampling technique has been proposed and implemented to perform faster calibration procedures on passive impedance tuners [4].

The examples and the results are available in the recently published PhD Thesis.


  1. M. Zyari and Y. Rolain. Identifying multiple reflections in distributed lumped high-frequency structures. IEEE Trans. Microw. Theory Techn., 64(4):1306–1312, 2016
  2. M. Zyari, Y. Rolain, F. Ferranti, G. Vandersteen, and P. Bronders. Multi delay rational modeling of lumped-distributed systems. In 2017 IEEE MTT-S International Microwave Symposium (IMS), pages 1624–1627, June 2017.
  3. M. Zyari, Y. Rolain, and F. Ferranti. Rationalmulti-delay models for long interconnects. In 2017 IEEE 21st Workshop on Signal and Power Integrity (SPI),  May 2017.
  4. M. Zyari, F. Ferranti and Y. Rolain. An adaptive modeling method for the calibration of passive tuners. In IEEE MTT-S International Conference on Numerical Electromagnetic and Multiphysics Modeling and Optimization (NEMO) , Aug 2018.
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