Microwave absorption of film explained accurately by wave cancellation theory

Abstract It has been proved theoretically that in the field of microwave absorption, film and material are confused, and that the impedance matching theory (IM) which is usually applied to metal-backed film is inadequate. IM is defined by the difference between the absolute values of the input impedance of the film Z in and the characteristic impedance of open space Z 0 . Before the scientific community accepts any new theories, it is necessary to validate them with a variety of experimental data such as those obtained from films of different materials. By analysis of experimental data, it is shown here that the problems with IM cannot be solved even if different criteria such as the value of | Z in - Z 0 | or the phase difference between Z in and Z 0 are used and therefore it needs to be replaced by wave cancellation theory. The analysis of published data in this work supports the following conclusions. The value of reflection loss RL is determined by energy conservation, specific to film since it is related to the amplitude of the resultant of the two beams reflected from the two interfaces in the film and the angular effect from the phase difference between the two beams is vital for understanding microwave absorption from film.