Microwave measurements of the photonic band gap in a two-dimensional photonic crystal slab

We have measured the photonic band gap in the transmission of microwaves through a two-dimensional photonic crystal slab. The structure was constructed by cementing acrylic rods in a hexagonal array to form rectangular stacks. We find a band gap centered at approximately 11 GHz, whose depth, width, and center frequency vary with the number of layers in the slab, angle of incidence, and microwave polarization.