Abstract:We investigated the excitation of surface plasmon polaritons on gold films with the metallized probe tip of a scattering-type scanning near-field optical microscope (s-SNOM). The emission of the polaritons from the tip, illuminated by near-infrared laser radiation, was found to be anisotropic and not circularly symmetric as expected on the basis of literature data. We furthermore identified an additional excitation channel via light that was reflected off the tip and excited the plasmon polaritons at the edge of the metal film. Our results, while obtained for a non-rotationally-symmetric type of probe tip and thus specific for this situation, indicate that when an s-SNOM is employed for the investigation of plasmonic structures, the unintentional excitation of surface waves and anisotropic surface wave propagation must be considered in order to correctly interpret the signatures of plasmon polariton generation and propagation.

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A new design of compact micro strip antenna, based on a newly structure "E"SRR of metamaterial is proposed and designed using CST Microwave Studio. It has been found that the characteristics of new micro strip antenna with novel designed metamaterials placed in the same plane as the radiating element are comparable to the conventional patch antennas, whereas its gain, directivity, and radiating efficiency are remarkably improved. For the design and fabricated antenna, it shows that with the addition of split ring resonator, the frequency has been shifted from 2.38 GHz to 2.4 GHz. The return loss of this antenna increased from −60 dB to −70 dB. The realized gain increased from 7.1 dbi for the antenna alone to 7.31 dbi for the meta-material antenna. Prototype for all antennas are fabricated and measured. Good agreement between the measured and simulated results is achieved. K E Y W O R D SCST microwave studio, ESRR, metamaterials, microstrip patch antenna, RFID

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