Tunable Microwave Filters using YIG Grown by Liquid Phase Epitaxy

Original work is described on the application of refinements in Liquid Phase Epitaxy (LPE) of yttrium iron garnet (YIG) to the fabrication of tunable microwave filters. The advantages in cost and performance of this approach over the conventional YIG sphere technology are discussed. The developments in the LPE of YIG and the reactor used are described. The viability of LPE-YIG filters is demonstrated by linewidth and external Q (Qe) measurements on bandstop and bandpass filters. Techniques for resonator-resonator coupling are described. The design parameters and measured performance of multi-pole bandpass filters are compared and shown to be consistent.