Circularly Polarized Reconfigurable Water Based Microstrip Antenna

Abstract

A water microstrip antenna (WMA) with polarization reconfigurable states is investigated in this communication. The antenna has low profile, flexible and low cost structure. The water is held by a container from a dielectric material and the antenna is fed by an L-shaped probe. The radiation characteristics of a single element WMA with circularly polarized radiation for WiMAX and RFID systems at 2.44 GHz are investigated. The WMA has a high radiation efficiency of 95% with 28.6 % matching bandwidth. The effect of varying the environmental temperature and water salinity on the performance of the WMA is investigated. To realize the polarization re-configurability, two adjacent containers are designed with a single feeding. Therefore, the polarization of the proposed antenna is switched between three different states, according to the water injection or extraction from containers. When a single container is filled with water and the other is empty the radiated field will have right-hand or left-hand circular polarization. When both containers are filled with water a linearly-polarized (LP) wave is radiated. Consequently, the reconfigurable polarization is obtained by controlling the water flow, where a wide circular polarization bandwidth of 29.5 % is obtained.