Face-centred-cubic photonic crystals with overlapping stop bands are s
tacked in tandem to obtain an ultrawideband photonic crystal. This cry
stal has a stop band that extends from 16 to at least 25GHz and has a
minimum rejection of similar to 7dB at normal incidence. Different sta
cking configurations have been studied, and cavity modes between nonad
jacent crystals with overlapping stop bands have been observed.