1.1.3    Relation between a wavelength and medium parameters (permittivity and permeability)

The relation between a wavelength and medium parameters can be observed using ppw3.QWpro file that needs to be loaded in QW-Modeller.

It is also possible to modify ppw1.QWpro, which for that purpose should be opened in QW-Modeller. To observe the relation between a wavelength and material properties with good accuracy it is required to change the space discretisation. In the Model tab press Settings  icon and in the appearing dialogue set the cell size in the direction of wave propagation (X dir) to 0.25 mm (see Fig. 7).

Fig 7 Dialogue window for mesh settings.

Now, the new medium in which the wave will propagate should be introduced and assigned. The procedure of doing this is as follows:

·       In Geometry tab press  button. The dialogue as in Fig 8 will be opened.

·       Press Add button. A window for defining medium parameters, as in Fig.9 appears. Define the material name as “dielectric” and assign permittivity value of ε_r=4. If required, material colour can be changed, using Pen option.

Fig 8 Dialogue window for materials editing.

Fig 9 Example of correctly filled window for new material adding.

It is required to assign the new medium to the box in which the wave propagates. For that purpose pick the Box object from the project tree by clicking on it and in the Data tab of Property Editor (see Fig. 10) click on the Medium row. The Set Medium option will be available.

Fig 10 Element properties window of Data tab.

Pressing this option invokes Project Media dialogue (Fig. 11), from where "dielectric" medium should be chosen.

Fig 11 Dialogue window for materials available in the project.

Save the project with a new name and run simulation using  button.

In the QW-Simulator measure the wavelength for the considered case. According to the formula given above, the wavelength is equal to  .

Due to improved space discretisation the precise wavelength value of 37.5 mm is calculated in the simulation.

The display observation allows noticing the change of plane wave speed (Property 1). It is advised to check how the speed of a plane wave depends on μ_r change.