Moisture vulnerability of antenna operation in UHF band

Abstract

Behavior of the propagation medium in reaction with electromagnetic fields is described by its dielectric permittivity; this electric property is a function of the physical characteristics of the medium and those of the propagating wave. Among the parameters, which considerably affect the dielectric permittivity of a medium, its water content. In fact, when the snow wetness varies from 0 to 50% in the melting layer, real part of the mixture permittivity varies from 1.47 to 5.86. Similarly, when soil moisture varies from 0 to 40% real and imaginary parts of effective permittivity of soil, air and water mixture vary from 4.13 to 24.85 and from 0 to 3.44 respectively. This dynamism in the permittivity as a function of the humidity is able to alter the efficiency of the antenna within the application. In this paper, we propose a study to analyze the impact of wetness on the performance of a dipole antenna with central frequency of 900 MHz. The study was carried out by simulating the behavior of the dipole antenna model in Finite Element Method (FEM) full wave simulator with different values of the water content of two propagation mediums: melting layer and soil. Simulation results concerning the resonant frequency, bandwidth, directivity are presented through paragraphs of the paper.