  We experimentally investigate the vortex induced energy losses in niobium
coplanar waveguide resonators with and without quasihexagonal arrays of
nanoholes (antidots), where large-area antidot patterns have been fabricated
using self-assembling microsphere lithography. We perform transmission
spectroscopy experiments around 6.25 and 12.5 GHz in magnetic field cooling and
zero field cooling procedures with perpendicular magnetic fields up to B=27 mT
at a temperature T=4.2 K. We find that the introduction of antidot arrays into
resonators reduces vortex induced losses by more than one order of magnitude.
