Microwave circulator using yttrium iron garnet film

Circulators and isolators are well-known nonreciprocal devices and widely used in the communication engineering. Most of circulator structures consist of polycrystal ferrite substrate having the thickness of more than 1 mm. Recently ferrite film circulator has been actively studied because of the advantage of low loss and easy integration with semiconductor device such as FET. This paper treats the theoretical and experimental results of the circulator using yttrium iron garnet (YIG) film epitaxially grown on gadolinium gallium garnet (GGG) substrate