V.L. Taylor, SCF.E/RADC Post Doctoral Program, Hanscom Am, MA 01731

mechanical abrasion of the YIG. They abraded the YIG in a preferential direction using 300 grit silicon carbide to produce a graded transition. abrading the GGG support crystal before growing the epitaldal YIG on it, so that the YIG film grew with lossy defects. For surface waves (MSSW+), YIG abrasion reduced the passband ripple from about 5 dB to less than 1 dB over most of the 800 MHz band centered on 3.0 GHz. For volume waves, YIG abrasion reduced ripple from about 20 dB to 2 dB over a 600 Non-uniform magnetic biasing fields reduced end reflections of an MSW delay line, as seen by reduced echoes in a pulse-transmission display, and reduced pass-band ripple in the corresponding insertion loss display covering the 2.5 to 3.5 GHz range. For surface waves, permalloy slugs perturbed the bias field outside the propagation path reducing passband ripple from more than 10 dB to less than 4 dB over a 400 MHz section of the band and less than 1 dB over 200 MHz. Unmatched insertion loss of 11 dB was not increased. ppiz band in the Same GGG abrasion was For volume waves, considerable echo suppression was slightly less effective. achieved. longer periodicity with broad insertion loss minima. Considerable improvement seems likely for volume wave performance. has an advantage over abrasion techniques previously reported in that the garnet strip is not modified. Experimental results and fabrication methods will be described. They tested a similar technique by