4.1 Drawing the structure

Now we proceed to creating the geometry stage. Firstly we need to draw the strip of the microstrip filter as a sketch in XY plane. We draw it at the offset of 0.795 mm along Z axis, which corresponds to the thickness of the substrate, which will be introduced to the project later. All dimensions of the strip are given in the next picture. The element's medium should be metal thus, we set Active medium accordingly.

Strip of the microstrip filter drawn as a sketch.

Strip dimensions.

When the sketch is finished we need to define the element as a thin layer. To do that we need to select the sketch from the list in the Tree by clicking on it. After that the Thin Layer button available in Thin Layer... section of Geometry tab becomes active.

Thin Layer button active after selecting strip sketch.

It is required to press that button for the chosen sketch, so that it will be recognised as a thin layer.

Strip element recognised as a thin layer.

Having the strip drawn we can now draw a substrate under it. The substrate is made of dielectric material with relative permittivity equal to 2.2. Before drawing the substrate we need to introduce its material to the project. To do that we press Media button and in the Project Media dialogue that will appear, we Add substrate_medium with parameters as shown below. Pressing OK button here will accept the settings and OK button in Project Media dialogue accepts adding the medium to the project.

Edit medium dialogue with substrate_medium parameters.

We can now draw the substrate element under the strip. For that purpose we press Create a Box button from the Primitives section and set the parameters of the substrate.

Create Box dialogue with parameters required for the substrate.

Drawing the ground plane in this case is not necessary since the default boundary conditions enforced by the QW-Modeller at all the project boundaries are PEC. Thus, if it is not changed by the user by purpose, at the bottom of the substrate PEC will be enforced.