No abstract

No abstract

Long period grating fibers are special class of fibers which are produced by periodic modulation of the refractive index of the core. This perturbation leads to forward guiding mode to couple with co propagating cladding modes depending on the phase matching condition. This coupling causes the cladding modes to attenuate during propagation in the fiber and leads to dips in the attenuation bands at discrete wavelengths in the transmission spectrum. These bands are shifted when the LPG is exposed to temperature, strain, refractive index changes in surrounding environment etc. This forms the basis of LPG sensor. The properties of LPG are modified in order to achieve the required sensitivity towards any measurands as per the applications. The performance of LPG by modifying the properties of LPG is reviewed.

No abstract

Abstract-Two novel configurations for increasing the impedance bandwidth of the microstrip patch antennas have been proposed for operating in the 3G mobile communication range. In these configurations, additional resonators of semicircular shape rather than conventional rectangle are gap coupled to the non-radiating edges of the fed rectangular patch. A comparative study is done between the antennas of the same size with two semicircular parasitic patches and an antenna having a combination of semi-circular and rectangular parasitic patches. Compared to the available broadband antennas, the proposed antenna structure gives a better bandwidth.Index Terms-Gap coupling, microstrip antennas, 3G, VSWR.