Tunable Frequency Selective Surface based on ferroelectric ceramics for beam steering antennas

A Tunable Frequency Selective Surface (FSS) as a transmission array with beam steering capability is presented. A FSS is implemented on screen printed Barium-Strontium-Titanate (BST) thick film ceramic. The FSS is designed to behave as a band pass filter and is made tunable by loading with a BST layer, which is placed beneath the metallic structures. The tunable FSS (TFFS) is simulated for different permittivities of the BST film which results in a shift in the filter response and therefore, a phase change in the wave. In the measurement of a prototype, a maximum phase shift of 116 degrees is obtained at 10 GHz, while transmission and reflection levels are kept invariable.