The analog method of measuring the cut-off wavelengths of TE waves in waveguides of arbitrary cross-sections does not seem to appear in literatures. In this paper one such analog method is presented. The conducting walls of a section of the waveguide to be investigated is replaced by non-conducting walls

the guide so formed is filled with electrolyte

two point electrodes

symmetrical with respect to the plane bisecting the guide are situated one at the top and the other at the bottom planes of the guide section

electric current is sent through the electrolyte. The potential problem of such a current field is solved

giving the potential distribution function in the electrolyte. By measuring this potential

we can find the cut-off wavelength of the TE wave in the waveguide under investigation.