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A key thrust within each branch of
the Department of Defense is to develop next generation microwave communication technologies for a highly mobile, adaptable
and agile military. Such technologies are to be fully integrated into systems on a chip that are light-weight,
low-profile, cost effective and reliable in hostile military environments.
Critical to point-to-point communication and RADAR systems are the class of microwave devices that employ ferrite materials.
It has been shown over the past several decades that microwave ferrite materials can be used effectively in circulators,
filters, isolators, inductors and phase shifters, to name a few. However, for each of the cited devices, the common
practice is to build them using large bulk ferrite samples. In an age when military communications systems are to be highly
portable and fully integrated into a small chip, this approach is no longer satisfactory. Instead bulk ferrite materials
are to be replaced with thick and thin ferrite films integrated into a single silicon package. The fabrication of such
films and the incorporation of the same into novel microwave communication devices are important research thrusts of the
military.
To date, there has been limited success in the growth and development of ferrite thick films for microwave communication
applications. This is particularly true for the class of hard ferrite films for circulator and isolator devices,
where deposition growth rates, high loss characteristics and fabrication problems (to name a few) have prevented prototype
devices from leaving the test bed.
At the University of Idaho, AMFeR conducts research on the growth of thick, low loss, self-biased hexa-ferrite films on a silicon substrate for wideband circulator devices. Several sputtering and deposition methods will be explored for thick-film fabrication. These methods include chemical vapor deposition (CVD), plasma enhanced CVD (PECVD), magnetron sputtering, and liquid phase epitaxy deposition techniques. The characteristics of c-axis hexa-ferrite, self-biased films, as required for proper circulator operation in the millimeter bands, have been specified as follows: thickness on the order of 20-50 microns, an internal effective field on the order of 17,000 Oe, a magnetic saturation on the order of 5,000 G, a coercive field on the order of 3,000 Oe, an FMR line-width on the order of 300 Oe at 35 GHz and a loss tangent on the order of 0.005. Such films will be characterized in terms of their micro and macro magnetic properties using experimental techniques. Data obtained from micro-magnetic simulations will be compared with experimental data to validate the predictive capabilities of the analytical and numerical models. A millimeter-wave circulator will be designed, fabricated and tested for its microwave properties. Acceptable microwave properties include a return loss of 20 dB, an isolation of 20 dB and an insertion loss of .5 dB.
email:
phone:
fax:
mail:
(208) 885-6500
(208) 885-6840
MRCI, University of Idaho
P.O. Box 441024
Moscow, ID 83844-1024