Simulation

First begin by examining this simulation of the propagation of an electromagnetic wave along a cavity. Here the waves travels in the z (blue) axis direction. The magnitude of the x component of the electric field at each point in space is shown in red while the y-component is shown in green. Yellow indicates overlap of the x and y components. The initial display shows the magnitude in three dimensional space. Alternatively a cross-section can be displayed for which either the magnitude or the direction of the field can be displayed. Sliders vary the size of the box, the sharpness of the grid, the speed of the calculation, the incident frequency of the radiation and the brightness of the display. The lower box shows the available modes that can propagate through the waveguide (there will be further explanations on these modes in the reading). Any mode selected will be displayed. Drag in the image to change the view and scroll to zoom.

Try experimenting with a few of the following tasks:

• What is the effect of varying the size of the box?
• Try selecting a different mode (Try increasing the dimensions to allow more modes to propagate). What changes?
• For each mode, examine what happens to the electric field at the walls of the waveguide. View the x-y cross-section and look at the direction of the field.
• Decrease the frequency of the electromagnetic radiation. Now what happens?

Simulation by Sam Peet.

Try it yourself. Download a template file in:

• Matlab
• Python
• Gnuplot