  The potential to control the number of the spin-wave band gaps of a magnonic
crystal (MC) by variation of its geometry is investigated by numerical
simulations. The magnonic crystal is represented by a micro-sized planar
ferromagnetic waveguide with periodically variable width. By choosing a
step-like or sinusoidal variation of the width, the magnonic crystal reveals
multiple or single band gaps, respectively. This allows for additional degrees
of freedom in the design of MC based microwave filters and phase shifters with
desired characteristics. The MCs band gaps have been studied in the space and
frequency domains exploring the spin-wave spectrum dependence on the probing
position inside the magnonic crystal.
