Title :
Cutoff Phenomena for Guided Waves in Moving Media
Author :
Du, L.J. ; Compton, R.T., Jr.
fDate :
8/1/1966 12:00:00 AM
Abstract :
This paper treats the propagation of electromagnetic waves in the interior of a waveguide that is filled with a moving medium. The medium is assumed to be homogeneous, isotropic, and lossless, and to move with a constant velocity along the axis of the waveguide. The Maxwell-Minkowski equations for the electromagnetic fields are solved by means of a pair of vector potential functions similar to those frequently used for stationary media. The fields inside the waveguide are derived for both rectangular and cylindrical waveguides. The well-known cutoff phenomenon for a waveguide is found to be modified in an interesting way when the medium inside the waveguide is moving The results show that for a slowly moving medium (a medium for which n/sp, Beta/<1, where n is the index of refraction and Β is the velocity of the medium divided by the velocity of light in vacuum/, there are two critical frequencies, separating three frequency ranges in each of which there is a different type of propogation. For a high-speed medium (nΒ<1), it is found that there is no cutoff phenomenon at all, although there is one critical frequency separating two frequency ranges in which the propagation is different.
Keywords :
Cutoff frequency; Electromagnetic fields; Electromagnetic propagation; Electromagnetic scattering; Electromagnetic waveguides; Frequency conversion; Laboratories; Magnetic field measurement; Maxwell equations; Rectangular waveguides;
Journal_Title :
Microwave Theory and Techniques, IEEE Transactions on
DOI :
10.1109/TMTT.1966.1126275