Comments on "A New Concept for Broadbanding the Ferrite Substrate Circulator Based on Experimental Modal Analysis" [Letter]

In the above paper the authors concluded, from a modal analysis of microstrip ferrite circulators, that the combination of two adjacent modes should be used for broad-banding circulators, which do not require quarter-wavelength matching transformers. Upon careful examination of their results, it can be shown that Miura and EIashimoto actually produced conventional below resonance circulators---transformers included.