Description: Ferrite based isolators and circulators have been successfully demonstrated at microwave, millimeter-wave and submillimeter-wave frequencies. These components are nonreciprocal and thus highly useful for controlling standing waves and directing signal flow in frequency multiplier cascades, heterodyne, radar, radiometer, and other systems commonly deployed by NASA. However, at the higher frequencies the performance is degraded in terms of bandwidth and loss which severely limits their usefulness. Although there is a demonstrable need for these components, there are relatively few vendors. Most of the commercially available components were developed more than forty years ago and there has been little effort at modernization. Recent advances reported in the literature suggest that the loss in Faraday rotation isolators can be significantly reduced. Using modern electromagnetic simulation tools, we propose to design millimeter-wave and sub-millimeter-wave ferrite components that exhibit significantly reduced loss, and improved power handling and bandwidth. Initial work on the development of a W-band isolator is underway. Ferrite cores have been manufactured and the impedance matching structures have been designed. We plan to demonstrate the effectiveness of our approach within the six month timeframe of the SBIR Phase I program. We have also successfully modeled Y-junction circulators that accurately predict performance similar to those available in the commercial market and are now working on several approaches to increase the bandwidth of these devices. A preliminary design operating at 160 GHz has been completed. In the Phase I program, the design will be refined, built and tested. Beyond Phase I, our goal is to develop a full line of ferrite components operating from 75 GHz to over 320 GHz with significantly improved performance over the current state-of-the-art.

Benefits: The proposed ferrite components would find immediate application in heterodyne receivers used in NASA's Submillimeter Missions such as Marvel, VESPER, MACO as well as earth observing satellites such as SIRICE. They are also useful in a broad range of laboratory instrumentation for the development of millimeter-wave and submillimeter-wave sources, detectors, receivers and systems. They are broadly used in scientific instruments for plasma diagnostics (ITER), chemical spectroscopy, biomaterial analysis, and radio astronomy. These components are fundamental building blocks that find application in virtually any system working at millimeter-wave, submillimeter-wave and terahertz frequencies.

High frequency ferrite components find a broad range of application in military systems that include compact range radar, imaging systems, covert communications systems, and chemical and bio-agent detection systems. There are potential applications in biomedical systems for the real time analysis of skin diseases, portal security scanners, high frequency data links and industrial process control systems. There is an immediate need for these components in frequency extension modules for vector network analyzers operating from 75 GHz to over 500 GHz. They are fundamental building blocks used in many systems operating in millimeter-wave to terahertz frequency bands.