Tunable microwave transmission in a periodically corrugated waveguide

The main physical phenomenon caused by periodicity is Bragg reflection. It results in the opening of the forbidden gap in the spectrum of the periodic structure. The Bragg reflection occurs both in the case of unbounded periodic medium as well as in a case of a bounded periodic structure like a periodic waveguide. However, in the waveguide geometry dispersions become more complex due to their folding and crossing. As a result, besides Bragg reflections there arise non-Bragg reflections in the periodic waveguide. The spectrum of a planar waveguide acquires qualitatively new, and very promising from practical point of view, features if the periodicity is introduced into the waveguide by the lateral modulation. In the latter case the transmission properties become controllable due to opportunity to change the lateral modulation profile. For example, gaps can be tuned by means of shifting of periodic boundaries [1-3].