Abstract
YIG ferrite is widely used for microwave applications such as isolators and circulators. This paper studies the origin of intermodulation distortion (IMD) in microwave isolators in terms of the influence of the ferromagnetic resonance linewidth (ΔH), which is a material property of YIG ferrites. ΔH is affected by the non-uniformity of the spin direction under a dc field, which results from crystal anisotropy and the demagnetizing field around pores. The IMD was decreased by minimizing ΔH, which in turn was achieved by minimizing these two contributions separately. It also appeared that the input power dependence of IMD was increased by using low-anisotropy YIG ferrites.
