Thermal antenna behavior for thin films structures

We show that under proper conditions thin films structures behave like thermal sources that are able to emit radiation in well defined directions over a broad spectral band for both polarization states of light. This effect results from the quantization of modes inside the structure as in a Fabry-Perot resonator. A theoretical demonstration of this effect is given using the matrix transfer method. This result is similar to the best efficient reported results with gratings but using a completely different physical principle [J. J. Greffet et al., Nature 416, 61 (2002)].