Low-Sintering-Temperature Ferroelectric-Thick Films: RF Properties and an Application in a Frequency-Tunable Folded Slot Antenna

This investigation is one of the first steps toward the realization of low-cost, mass-producible, tunable antenna applications utilizing an integrated ferroelectric-thick film made of bariumstrontiumtitanate material. The dielectric properties of the electric-field-adjustable fired BST thick film are presented in the frequency range of 16 GHz. The key advantages of the material are high tunability (25% with 2.5 V/mum), compatibility with silver electrodes, and the ability to produce film thicknesses down to 25 mum. The utilization of the material is demonstrated by tuning the operating frequency of a folded slot antenna with an integrated variable capacitor. In addition, the impact of tuning on the antenna's total efficiency and radiation pattern is experimentally studied through a comparison with the performance of a reference antenna not incorporating the varactor.