Title: Compact magnet-less circulators and isolators for Ka-band radar and other instruments
Presenting Author: Douglas Linkhart
Organization: Metamagnetics Inc.
Co-Author(s): Lee Burns, Michael Geiler, Ogheneyunume Obi, Timothy Tiernan

Abstract:
Metamagnetics’ self-biased (magnet-less) circulators and isolators allow integration of more devices in a given volume. Funded in part by NASA ESTO Advanced Component Technology grant NNX15AB39G and NASA SBIR projects NNX14CP03C and NNX15CP73P, Metamagnetics, Inc. (Canton, MA) has developed KA-band low-loss self-biased circulators and isolators that conform to planar circuit topologies. These circulators and isolators are 90% thinner than traditional microstrip circulators and isolators because they do not require external magnets to provide bias field. Metamagnetics’ isolators and circulators have higher operational reliability than externally-biased circulators, as there are no bonded external magnets that would be susceptible to dislocation due to shock or vibration, such as is experienced during launch or deployment. For Aerosol-Clouds Ecosystems mission a circulator was realized with less than 0.8 dB insertion loss and more than 20 dB isolation over an operating temperature range of -25 °C to +75 °C and storage and processing temperatures from -55 °C to +200 °C. Because of its low profile height this circulator enables new phased array antenna implementations, such as collapsible feed arrays for example, that have not been possible with traditional bonded magnet devices. They also allow very small element spacing for high-performance, dense phased-array antennas. Substantially smaller than waveguide devices, they can be designed using microstrip or stripline topology for wire or ribbon bonding of interconnections, or as drop-in or surface mount components. The enabling technology for the self-biased circulators and isolators is Metamagnetics’ new low-loss ferrite material. Significant advances were achieved during the NASA ACT program to reduce dielectric loss as well as the variation of dielectric loss with temperature. Metamagnetics’ circulators and isolators enable high-density sensor design to help optimize instrument performance in a defined volume, at low cost and with high reliability.