This book, first published in 2002, discusses challenges facing the implementation of an affordable tunable RF and microwave device technology. Low cost, tunable, microwave devices will have a tremendous impact on a variety of commercial and military systems, including tunable band-select filters for wireless communications, phase shifters and true time-delay devices for electronic scanning antennas, tunable radiating structures for frequency hopping, and tunable transformers to reduce RF impedance mismatch. Papers address topics from materials issues through devices and even a system-level demonstration of electronic beam steering. Specific materials issues discussed include: new tunable materials; issues of tunability, preparation and optimization of bulk and thin-film properties; materials, surface, and interface characterization; evaluation of material loss and loss mechanisms; effects of microstructure; and temperature stability. Phase shifters are featured and a new device concept for variable true time delay versus phase shift is introduced. A paraelectric lens is used to demonstrate electronic beam steering of an antenna at 10 GHz with about 2 dB of loss.
