High-Power Ferrite Stripline Circulators/Isolators

This proposal addresses the special needs of NASA facilitating the use of space for commercial products and services. With regards to space communications antenna array systems are regularly installed with spacecrafts and satellites to transmit electromagnetic signals at high power. As such, circulators/isolators are needed to separate signal paths in T/R modules, providing protection over the receiver circuitries avoiding high-power incidence. When applied at high power, nonlinearity sets in at the ferrite junction area causing communication channels to couple with each other. This is called intermodulation which ultimately limits the usefulness of a ferrite junction to be applicable at excessive power levels. In the past we have analyzed this nonlinear problem and have identified the origin for intermodulation. We envision two techniques to be effective. The first technique is based on the DC consideration ensuring circulation action to occur without activating the adverse terms in the equations of motion responsible for intermodulation. The second technique is AC in nature, demanding the circulator operation to induce minimum excursion in the transverse component of the magnetization vector. Temperature compensated ferrites will be considered in Phase II, giving rise to stabilized operation of the circulator applied at high power.