The field displacement isolator

A nonreciprocal ferrite device (field displacement isolator) has been constructed with reverse to forward loss ratios of about 150 in the region from 5,925 to 6,425 mc/sec. The forward loss is of the order of 0.2 db while the reverse loss is 30 db. These results are obtained by using a single ferrite element, spaced from the sidewall of the guide. The low forward loss suggests the existence of an electric field null at the location of a resistance strip on one face of the ferrite. We discuss the various conditions, derived theoretically, under which the electric field null may be obtained and utilized. Furthermore, a method of scaling is demonstrated which permits ready design to other frequencies.