The present paper considers the rigorous solutions for electromagnetic waves transmitted and reflected by a medium of finite length with time-space periodic fluctuation, loaded in a rectangular waveguide, When an electromagnetic wave is incident upon the medium mod-ulated in a travelling wave fashion by a pump wave, the reflected and transmitted waves are shifted in frequency by +nω
1, (where n is an integer, ω
1 is the angular frequency of fluctuation).
The harmonic level of the reflected waves is much increased as the frequency of the incident wave approaches the cutoff-frequency of TE
10 mode of the rectangular waveguide. Measurement of the spectrum of the reflected waves can be utilized as a diagnosis of even a very slightly fluctuating medium. The theoretical results have been verified on examining experimentally the harmonic level of the microwave reflected by a plasma, weakly modulated (about 10
-4) by RF signal and loaded in the WRJ-10 waveguide.
抄録全体を表示