Advances in ferrite microwave materials and devices

The application of ferrites in non-reciprocal components is discussed, with the emphasis on broadband isolators and circulators. The performance of such devices may be characterized by the ratio f(max)/f(min) of the frequencies that define the edges of the frequency band, within which satisfactory performance has been achieved. For the best currently available devices this ratio is approx. 3:1, but larger values appear feasible according to a detailed analysis of the 'low-field, low-frequency loss' that limits the performance. (C) 2000 Published by Elsevier Science B.V. All rights reserved.