The cross-section method is an analytical tool used in the design of
components required for low-loss, highly efficient transmission of
electromagnetic waves in nonuniform waveguides. When the waveguide
dimensions are large compared with the wavelength, a fully
three-dimensional analysis employing modern numerical methods based on
finite element, finite difference, finite integration or transmission
line matrix formalisms is practically impossible and the cross-section
method is the only feasible analysis technique.
The method is not limited to oversized tubular metallic waveguides, but
is employed intensively in areas such as fibre optic communications,
antenna synthesis, natural waveguides (submarine, tropospheric and
seismic), microwave radio links (Earth or space) and the design of
absorbing surfaces and it may also be applied to many acoustic problems.
The application of the method in special cases such as cut-off and
resonant frequencies is covered, as well as the design of oversized
waveguide components such as tapers, bends, polarisers and mode
converters. Many useful formulas are given for the practical layout of
such transmission line components. The use of computers in the
application of the method and problems related to numerical analysis are
also covered.