Effect of Rainwater and Seawater on the Permittivity of Denim Jean Substrate and Performance of UWB Eye-Shaped Antenna

The effect of rainwater and seawater on the permittivity of denim jean substrate and performance of an ultrawideband (UWB) eye-shaped textile antenna is investigated in this letter. For the simulated and measured reflection coefficients in dry condition, it was found that the antenna operates at 2.4-10.9 and 1.6-12 GHz, respectively, with the simulated gain between 3.2 and 5.8 dBi from 2 to 12 GHz with efficiencies greater than 50%. The antenna can operate at the entire range in dry conditions when S11 ≤ -10 dB, but with limited performance under wet conditions. However, it cannot be used when immersed in rainwater and seawater. From the investigation, it can be shown that the permittivities of denim jean substrate under wet and immersed conditions are proportional to the permittivities of the absorbed medium (rainwater or seawater) at 2-12 GHz.