  Elastic metamaterials made from locally resonant arrays have been developed
as effective ways to create band gaps for elastic or acoustic travelling waves.
They work by implementing stationary states in the structure that localise and
partially reflect waves. A different, simpler, way of obtaining band gaps is
using phononic crystals, where the generated band gaps come from the periodic
reflection and phase cancellation of travelling waves. In this work a different
metamaterial structure that generates band gaps by means of coupling two
contra-propagating modes is reported. This metamaterial, as it will be shown
numerically and experimentally, generates larger band gaps with lower added
mass, providing benefits for lighter structures.
