Theoretical analysis is carried out and methods of experimental studies of multi-wavelength waveguide tracts are described, on the basis of which it is possible to create ultra-wideband communication lines and feeder lines with low losses. The influence of random irregularities on the properties of multi-wave lines is considered in detail. Theoretical conclusions are confirmed by the results of experimental studies. The book is intended for specialists in water engineering, high-frequency electrodynamics, communication theory, millimeter-wave measurements, statistics of random environments, as well as for senior students and graduate students of relevant specialties .