Magnetic field expression in a rectangular waveguide
Anm, the amplitude of each mode depends on the source, excitation of the waveguide and end conditions (and possibly obstacles in the guide). The author solves the differential equations for traveling waves in a hollow rectangular waveguide to find their general form without reference to the aforementioned factors.
The other book by the same author, 'Field theory of guided waves', deals with some specific problems (excitation of waveguides) and supplies formulas for the amplitudes of modes.