BST thin film capacitors integrated within a frequency tunable antenna

Ferroelectric (FE) thin film varactors can be a convenient technology for tuning miniature antennas. In this paper we present the design of a compact, agile, wire patch antenna integrating barium strontium titanate (Ba
_(1-x)
Sr
_x
TiO
₃
, BST) thin film interdigitated capacitors (IDC). The IDCs values were measured at different temperatures and bias voltages ranging from 0 to 120 V showing a capacitance variation of more than 40% between 11-13 GHz and up to 28% in the 2-3 GHz frequency interval. Their integration within a compact antenna design allows tuning its operating frequency on the whole WiFi band, with efficiencies higher than 70%.