2.4     Wavelength in a waveguide

It is known from Plane Wave tutorial that the wavelength of a plane wave is strictly related to the wave frequency. The wavelength in a waveguide is considered as a wavelength in a direction of wave propagation and its dependence on wave frequency is defined as follows:

where l₀ is a wavelength in a free space at a given frequency and l_c stands for the cutoff wavelength for a given waveguide dimensions and waveguide mode.

The frequency dependence can be investigated with wr340_3GHz.QWpro and wr340_6GHz.QWpro scenarios, where the WR-340 waveguide is excited with the TE₁₀ mode with two different frequencies. Load wr340_3GHz.QWpro project in the QW-Modeller and run the electromagnetic simulation in QuickWave. Open field visualisation window using  button in 2D/3D Fields tab of QW-Simulator. The display as in Fig. 18 should be seen.

Fig. 18 Ez component of electric field for TE10 mode in WR-340 waveguide at 3 GHz

Load wr340_6GHz.QWpro in QW-Modeller and run the simulation for this project. In QW-Simulator open field visualisation window using  button to obtain the display as in Fig. 19. The dependence of a wavelength in a waveguide on the wave frequency can be clearly seen.

Fig. 19 Ez component of electric field for TE10 mode in WR-340 waveguide at 6GHz