Electromagnetic wave propagation in almost periodic media

The problem of electromagnetic wave propagation in almost periodic media is investigated, and a solution is obtained directly from Maxwell's equations. The evaluation of this solution involves a generalization to almost periodic media of the Brillouin diagram of periodic media. The Brillouin diagram is used to place in evidence similarities and differences of wave propagation in periodic and almost periodic media. It is shown that although the periodic and almost periodic theories agree in many cases of interest, there exist cases in which distinct differences appear. In particular, these distinctions become apparent for media with closely spaced tones.