  In this paper, we study the radiation from embedded sources in
two-dimensional finite-size "photonic-quasicrystal" (PQC) slabs made of
dielectric rods arranged according to a 12-fold symmetric aperiodic tiling. The
results from our investigation, based on rigorous full-wave simulations, show
the possibility of achieving broadside radiation at multiple frequencies, with
high-directivity (e.g., 15 dB) and low-sidelobes (e.g., -12 dB). We also show
that leaky waves are supported by a PQC slab, and that the beamwidth is
directly proportional to the leaky-wave attenuation constant, which provides a
physically-incisive interpretation of the observed radiation characteristics.
