A four element phased patch antenna array using fluidic phase shifter

A phase shifter in microstrip was investigated in which narrow, hollow channels were located under a microstrip line. When the channels were filled with fluids having a dielectric substantially different than that of the microstrip substrate, the change in the wave propagation velocity produced a noticeable phase shift. For this study, water (with a dielectric constant of 78) and air were used to achieve a variable phase shift. The goal of this study was to use water-based fluidic phase shifters to create a four element patch antenna array in microstrip operating at 8 GHz where the beam steering could be controlled by filling a number of water channels per antenna. To achieve this, a series of channels 1 mm wide and 1 mm high, separated by 2 mm, were modeled in the substrate below the transmission line in ANSYS HFSS. These channels were modeled in a 1.52 mm high substrate of Rogers R04003C with a dielectric constant of 3.55. The channels were modeled as being milled from the ground plane side of the microstrip line. The full 4 element array was able to achieve a beam steering angle of up to 18° in either direction from boresight, for a total of 36°.