| Summary: | 碩士 === 國立交通大學 === 電信研究所 === 81 === By skin-effect, the electromagnetic field in the conductor
decay by an amount 1/e or 36.8 % after traveling a distance of
one skin depth. At microwave frequencies, for a good
conductor, this distance is very small. Foe gold, ds= 0.76
mm. In general, the thickness of metal is far more than the
skin depth. The result shows that most of current flow in a
good conductor occurs in an extremely thin regon near the
surface of conductor, and doesn't deep into the metal. At the
other extreme of microwave frequency range, we discuss the
increce of loss caused by the metal rough on inner surface of
waveguide at high frrquency range. The surface roughness of
finite conductivity metal of waveguide causes the increce of
propagation loss. The effect of the rough on the wide wall
surface had been done by Dr. C.-D. Chen. But in fact, the
current distribution of TE10 mode, the mostly utilized mode of
rectangular waveguide, distributes on the whole inner surface
of waveguide. The influence on the increce of propagation loss
caused by rough on narrow wall surface must be taken into
consideration. By the model of roughness, the rough of narrow
wall surfaces cause serious propagation loss than the wide wall
surfaces.
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