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Abstract-In this paper the propagation of electromagnetic waves in a medium with non zero conductivity is discussed, analyzing the dielectric properties of the sea water, in order to accurately characterize a wireless communication channel. Mathematical models for sea water dielectric constant, wavelength, propagation speed and path loss when an electromagnetic wave at 2.4 GHz propagates through sea water are presented. A Bow-Tie microstrip antenna that is required to overcome the high path loss and bandwidth requirements in sea water is studied. A dual-band antenna, with arcshaped circular slots, operating for IEEE802.11 b/g/n standards, at 2.4 GHz and 5.1 GHz for WLAN communications, with dimensions 1.4 cm 2 is implemented. Return loss, input impedance and gain have been extracted in order to characterize antennas' performance in a conductive medium.

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By utilizing meteorological data such as relative humidity, temperature, pressure, rain rate and precipitation duration at eight (8) stations in Aegean Archipelagos from six recent years (2007 -2012), the effect of the weather on Electromagnetic wave propagation is studied. The EM wave propagation characteristics depend on atmospheric refractivity and consequently on Rain-Rate which vary in time and space randomly. Therefore the statistics of radio refractivity, Rain-Rate and related propagation effects are of main interest. This work investigates the maximum value of rain rate in monthly rainfall records, for a 5 min interval comparing it with different values of integration time as well as different percentages of time. The main goal is to determine the attenuation level for microwave links based on local rainfall data for various sites in Greece (L-zone), namely Aegean Archipelagos, with a view on improved accuracy as compared with more generic zone data available. A measurement of rain attenuation for a link in the S-band has been carried out and the data compared with prediction based on the standard ITU-R method.