Miniaturized and reconfigurable CPW square-ring slot antenna using thin film varactor technology

Ferroelectric (FE) Barium Strontium Titanate (Ba_(1-x)Sr_xTiO₃, BST) thin film varactor technology is applied to the antenna miniaturization and reconfiguration successfully. CPW square-ring slot antenna is used as a design example, and antennas with and without integrated BST varactors were fabricated and characterized. Including the total ground, the size of miniaturized antenna is 0.12λ₀ × 0.12λ₀ which is reduced by 31% compared with antenna without the BST varactors. Moreover, the frequency of the miniaturized antenna with the BST varactors is reconfigurable from 5.8 GHz to 6.1 GHz with a low DC biasing voltage of 3 V. Both E-plane and H-plane patterns were measured for the antennas. Fabrication details and measurement setup are also presented.