This is the first report and investigation of a patch antenna in optical frequency range. Variety of plasmonic nanoantenna reported so far is good at enhancing the local field intensity of light by orders of magnitude. However, their far-field radiation efficiency is very poor. The proposed patch antenna emits a directional beam with high efficacy in addition to enhancing the intensity of near field. The nano-patch antenna (NPA) consists of a square patch of gold film of dimension 480 nm 2 , placed on a substrate of dielectric constant e r = 3.9 and thickness 150 nm with a ground plane of gold film of dimension 1,080 nm 2 . The NPA resonates at 210 THz and has gain nearly 2 dB and radiation efficiency 45.18 %. The NPA might be useful in variety of applications such as optical communication, nano-photonics, biosensing, and spectroscopy.

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This paper presents the simulation results obtained with a circular patch antenna having an off centered narrow ring slit. With a particular location of ring slit near periphery of circular geometry, antenna resonates at two different frequencies which lie in the lower and upper band of Wi-Max communication adopted by IEEE 802.16. The efficiency and gain of antenna at one of these frequencies are better than those at other frequency while directivity is more or less same at two resonance frequencies. Experimental work is underway to test these simulation results.