This Small Business Innovative Research Phase I project addresses the topic of size reduction of a ferrite junction at low frequencies. Circulators are needed to separate the signal paths in a T/R module to protect the receiver amplifier circuit. Also, isolators are required by a microwave system to reduce internal reflection of the signal. However, at UHF and L-band, the size of a conventional circulator/isolator junction turns out to be too big to be practically inserted in a space-limited environment. Although lump-element circuits using ferrite inductors and multiplexer circuits using semiconductor junctions may be employed instead, however, they are extremely narrow-band devices subject to low power ratings. Devices that are five times smaller in linear dimensions than the conventional junctions have been fabricated. By incorporating high dielectric materials with the junction ferrite even smaller junction sizes are expected, giving rise to miniaturized UHF/L-Band circulators and isolators. This research project directly applies to UHF/L-band power amplifiers deployed in space-limited environments in ground vehicles, ships, airline jets, satellites, and spacecrafts. Applications also include microwave radars operational over a long distance and future broadband cellular systems.
