An Eight-Port Frequency Reconfigurable MIMO Antenna Using Liquid Dielectrics

In this paper, an 8-port compact fluidic based frequency reconfigurable MIMO antenna is designed and developed. Eight modified U-shaped slots are deployed on the top surface of the substrate integrated waveguide cavity in 2×4 array pattern. These modified U-shaped slots are excited by eight coaxial feedlines. Four fluidic microwells are introduced at the corners of each U-shaped slots. The frequency reconfigurability in the designed MIMO antenna is obtained by filling all the microwells with air and different liquid dielectrics (acetone, ethyl acetate, distilled water). Moreover, the frequency reconfigurability can also be achieved by the different filling configurations of microwells with air and distilled water. The designed MIMO antenna possess frequency reconfigurability from 1.29-2.51 GHz. The measured results of the fabricated prototype match well with the simulated ones. The proposed MIMO antenna exhibits high inter-port isolations (>28 dB) in all the configurations within a compact size of 0.114λ<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub>. The peak gains of 4.75 dBi and 3.62 dBi is obtained for the designed MIMO antenna when all the microwells are filled with air and distilled water, respectively at their corresponding operating frequencies of 2.51 GHz and 1.29 GHz. The MIMO performance is investigated in terms of diversity gain (DG) and envelope correlation coefficient (ECC) and they are within the acceptable limits.