Development of a Ferroelectric Based Tunable DLA Structure

An experimental demonstration of a tunable Dielectric Loaded Accelerating (DLA) [1] structure is planned using a nonlinear ferroelectric with temperature‐ or voltage‐controllable permittivity. We designed and tested two prototype Ka‐band double layer ferroelectric‐ceramic structures (cylindrical and planar) consisting of linear ceramic layers (dielectric constant of 6.8) and BST(M) composite ferroelectric layers of 400–800 μm thickness and dielectric constant of 450–550. The frequency shift by temperature variation of the cylindrical Ka‐band tunable DLA of 14 MHz/° K has been demonstrated leading to an overall DLA structure frequency tuning range of 140–280 MHz with 10–20° K temperature variation. The Ka band prototype DLA structure demonstrated a 6 MHz frequency tuning range for a dc bias field design at 25 kV/cm field strength.