Advances in ferrite microwave materials and devices

Abstract 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 fmax/fmin 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.