The small wavelength utilizable range used for determining the optimum performance of photovoltaic and rectenna devices, compared to the broad band spectrum of solar or other heat sources, limits the energy conversion efficiency of such technologies. A selective emitter, with an emissivity profile that matches the receiver's characteristic bandwidth, can be used to improve the overall efficiency of such energy harvesting devices. This paper dompares simulated and experimental results of the design and fabrication of a selective emitter that can be used in the 8-12 mu m frequency range. The matrix transform method is used to calculate the radiative properties of one dimensional metal-dielectric photonic structures. By using genetic algorithm as a powerful optimization tool, the simulated design characteristics of such structure are adjusted to minimize the mean square deviation of the actual spectral emissivity from the target emissivity profile. Specifically, this paper presents and compares results of the simulated design and fabrication of selective emitters composed of alternating layers of Al2O3-SiO2 or Al2O3-SiC on an aluminum substrate. The output radiation of these selective emitters could be used as the input radiation to high efficiency rectenna devices.