Chapter Eight - Ferrites for RF Passive Devices

Abstract

Abstract Recent advances in mobile devices and telecommunications demand compact and high-performance radio frequency (RF) devices, including antennas, isolators, circulators, and inductors. Operation mechanism of these RF devices arises from strong coupling of magnetization dynamics with electromagnetic signals. Understanding the role of magnetism and effect of magnetic materials in the RF applications are, therefore, of great importance for the advancement of device design and performance improvement. Ferrites possess many attractive features for RF device applications such as the nonreciprocity, the frequency-dependent permeability, the magneto-dielectric properties, and high electrical resistivity and low eddy current loss at high frequencies. These characteristics can provide unidirectional wave propagation, device miniaturization, and RF performance improvement. This chapter focuses on the dynamic properties of ferrites and the analysis of fundamental characteristics of RF ferrite devices. The important role of ferrites in RF applications is demonstrated, and the ferrite fabrication techniques and device design methods are also discussed in this chapter.