Microwave absorption of film explained accurately by wave cancellation theory

The wave mechanics for microwave absorption film-Part 3: Film with multilayers

“…Using the wave superposition principle covered by general physics, the theoretical expressions of s11 and s21 for the conventional WMB can be obtained [36,39,46,71] by the conditions that Zk- where Zin(xk -) is the input impedance for WMB; The reflection coefficient RM(xk -) for an interface at xk is defined by s11 of the interface since incident waves at xk + are irrelevant for interface. Similarly, the transmission coefficient M(xk + ) for an interface at xk in Fig.…”

“…The structure-dependent EM response mechanisms as unveiled by artificial intelligence are believed to offer more opportunities for a precise prediction and optimization of EMW absorption performance." [1] However these difficulties are an inevitable consequence of confusing film and material [1,3,5,7,[32][33][34][35] in that film parameter reflection loss RL is wrongly applied to material [36,37].…”

“…The condition Zin = Z0 claimed by IM to be critical is a misinterpretation of Eq. ( 1) since nearly all the reported minima in RL/dB occur at positions where Zin  Z0 [36,48]. The real reason for the absorption peaks represented by |RL| is wave cancellation rather that the superficial reason claimed by the Zin = Z0 condition [46,48].…”

Wave Mechanics of Microwave Absorption Films: Part 3 - Multilayered Films

“…By employing the wave superposition principle, consistent with fundamental physics principles, we can obtain the theoretical expressions of s 11 and s 21 for the conventional WMB configurations [36,39,46,72], governed by the conditions…”

“…However, these challenges arise due to a common confusion between the terms "film" and "material" [1,3,5,7,[32][33][34][35]. Specifically, the misapplication of the film parameter reflection loss (RL) to the material domain has been a persistent issue [36,37]. It is crucial to recognize that the absorption mechanisms in films and materials differ fundamentally, primarily because of the influence of the two parallel interfaces present in films [38,39].…”