Modeling of Optical Nanoantennas.This book introduces several key techniques for such modeling, many of which are used in commercial design tools. The absorption, scattering, and extinction fields of a homogenous and coated spheroidal nanoparticles in a variety of surrounding medium due to an incident plane wave is studied. The applicability of the modified long wavelength approximation to ellipsoidal particleswith size less than 10% of the incident wavelength was discussed, and an analysis of its accuracy in comparison to Mie theory and measured experimental results was presented.The optical properties of plasmonic nanoantennas are investigated in details using the finite integration technique (FIT) and discrete dipole approximation (DDA). The validity of these numerical techniques are verified by comparison to the exact solution generalized Mie method (GMM). The influence of thegeometrical parameters (antenna length, gap dimension and shapes) on the antenna field enhancement and spectral response is discussed.The promising results of this study may have useful potential applications in near-field sample detection, optical microscopy, optical sources, detectors and networks.