>If I define the spatially varying line width numerically, I'd like to select along which axis, and this is not clear from the help documentation.nIn online HELP Library it is here:|HFSS%2520Help|Assigning%2520Materials|Adding%2520New%2520Materials|_____4nSpatially Dependent Materials in HFSSnEach spatially dependent object should have its own coordinate system as that would associate each with a separate origin point. The following images show the coordinate systems for each stripline with the Y origin at the start of the object.nX Y Z are not the same as $-project variables. You can not put them in project variable formulation. But you can use them in material editor.nHowever there is no way to check it in report, so I would avoid using it, or make an experiment with equivalent propagation in subdivided model, and similar modulated model.nMost researchers I know prefer subdividing manually.nn>However, when there are reflections I get a very different input impedancenI wonder how you define the input impedance of the magnetostatic wave. If you have a coplanar transducer, it is also not the best structure to find an equivalent load impedance because of complex modal composition. Why don't you use simple thin-wire as in classic works?nIf that's a practical model, i would model the whole transducer(antenna) and sweep its width until best matching, which will equalize the input impedance with the wave port impedance.nnAnd as znaqvi said, try not to miss the unit. When dividing, or taking trigonometric function, the unit may be lost and you have to multiply the float value with *1mm or 1mn