Magnetism in Microwave Devices

Abstract

The functions of ferrite components in advanced microwave systems are briefly outlined, and the principal requirements described. The successful development of these sophisticated devices is the cumulative result of contributions from many areas of basic research and technology. As an example of the dependence of device performance on diverse efforts, the status and evolution of ferromagnetic digital phasers are reviewed. In this instance, materials research, ceramic technology, methods of numerical analysis, and the understanding of basic damping mechanisms have all contributed to the realization of practical devices. The application of ferrite devices to microwave integrated circuits is also outlined and some recent experimental results given. Other new trends in the field of microwave ferrite devices are briefly mentioned, as are areas most in need of further research.

High-efficiency gigahertz frequency doubling without power threshold in thin-film Ni81Fe19

“…Nonlinear effects in magnetization dynamics, apart from being of fundamental interest, 1-4 have provided important tools for microwave signal processing, especially in terms of frequency doubling and mixing. 5,6 Extensive experimental work exists on ferrites, 1,4,6 traditionally used in low-loss devices due to their insulating nature and narrow ferromagnetic resonance (FMR) linewidth. Metallic thin-film ferromagnets are of interest for use in these and related devices due to their high moments, integrability with CMOS processes, and potential for enhanced functionality from spin transport.…”

Performance improvement of S-band phase shifter using Al, Mn and Gd doped Y3Fe5O12 and sintering optimization

“…The bi-static characteristics of phase shifter make it an attractive component applied in phase-array radar system [6]. For our work, the hysteresis characteristics of ferrite, such as 4pMs about 700 kG, H c about 0.6 Oe, SQR about 0.85 are required for S-band phase shifter applications [1,2,5,6].…”

“…In order to properly control the microwave properties for the devices applied, the characteristics of hysteresis loop is very critical [2]. Mn, Al substituted YIG possess narrow DH with low H c at relative low 4pMs, which could be employed to the latching phase shifter at S-band frequency range [3,4].…”

Effect of particle size of as‐milled powders on microstructural and magnetic properties of Y3MnxAl0.8‐xFe4.2O12 ferrites

“…Three sublattices are present in the garnet structure; the dodecahedra c ‐site is occupied by three Y 3+ , the octahedral a ‐site is occupied by two Fe 3+ , and the tetrahedral d ‐site is occupied three Fe 3+ . The Y 3+ and Fe 3+ present in the sites are trivalent, making YIG exceptionally suitable for magnetic studies . Notably, the magnetic moment of Yttrium is insensitive to the crystalline field, and the super‐exchange anisotropy is zero due to the absence of net orbital angular momentum (usually denoted as L ).…”

“…YIG ferrites are often used in microwave phase shifters for scanning radar beams . To effectively control the microwave properties for the devices applied, the characteristics or the shape of the hysteresis loop and the magnetic properties are critical . However, the need for a phase shifter that can be switched in a few microseconds has placed a new emphasis on ferrite.…”