Simulation and experimental study of a non-reflective filter based on a strip three-wire coupled line

Abstract: The COMSOL Multiphysics system simulates a non-reflective filter with a three-wire coupled strip line and concentrated RLC elements. The dependence of frequency characteristics of the coupled lines on the thickness of the dielectric layer separating the coupled current-carrying strips from the third conductor, as well as on the gap between the current-carrying strips, is inves-tigated. It is shown that the introduction of an additional strip with a floating potential makes it possible to obtain a strong electromagnetic coupling between the current-carrying strips, which is necessary to obtain the required characteristics of non-reflective filters. An experimental study of the frequency char-acteristics of the non-reflective filter is carried out. The paper proposes a filter design with improved characteristics achieved by optimizing parameters of the coupled line with an additional strip line. The theoretical relevance of the paper is in the insights it offers regarding the effect of geometric parameters on the electromagnetic properties of coupled lines. Its practical value is in the creation of non-reflective filter for radio engineering sys-tems that require additional measures to reduce reflections be-tween cascades.

Keywords: frequency characteristics, non-reflective filter, concentrated rlc elements, three-wire coupled lines