Current status of thin film (Ba,Sr)TiO3 tunable microwave components for RF communications

The performance of proof-of-concept ferroelectric microwave devices has bee n moving steadily closer to the level needed for satellite and other rf com munications applications. This paper will review recent progress at NASA Gl enn in developing thin film BaxSr1-xTiO3 tunable microwave components for t hese applications. Phase shifters for phased array antennas, tunable filter s and tunable oscillators employing microstrip and coupled microstrip confi gurations will be presented. Tunabilities, maximum dielectric constants, an d phase shifter parameters will be discussed (e.g., coupled microstrip phas e shifters with phase shift over 200 degrees at 18 GHz and a figure of meri t of 74.3 degrees /dB). Issues of post-annealing, Mn-doping and BaxSr1-xTiO 3 growth on sapphire and alumina substrates will be covered. The challenges of incorporating these devices into larger systems, such as yield, variabi lity in phase shift and insertion loss, and protective coatings will also b e addressed.