Characterization of photonic band resonators for DNP NMR of thin film samples at 7 T magnetic field

•Several configurations of PBG resonators in the DNP probehead were characterized.•The gain in mm-wave power at the sample has been improved to 50-fold vs. mirror-only setup.•The gains strongly depend on the arrangement of dielectric layers next to the sample.•Odd-numbered arrangements represent a promising avenue for further boosting the mmW power gain.•Results are rationalized in terms of effective finesse and finite-element simulations.