Arc plasma fabricated phase shifter elements
It has been established that the arc plasma process can be used to fabricate ferrite phasors. The resultant ferrite-dielectric composite, except for the coercive force, has excellent microwave device characteristics. With the advent of a dielectric possessing optimum temperature coefficient of expansion, a phasor can be arc plasma sprayed which will be economical and exhibit the required device performance for phased arrays. The greatest economic impact of the arc plasma is expected to be in phasors requiring thin ferrite walls, since these are more difficult to fabricate by current processes and can be arc plasma fabricated at rapid rates. It should be noted that to achieve low cost phasors with the arc plasma technique, massive production numbers of phasors (in excess of 100,000 units) (6), are not required. That is, one can arc plasma fabricate a relatively small number of phasors and still maintain the economics of this technique.
Arc Plasma Deposition of Nickel Zinc Ferrites
Abstract : Nickel zinc ferrite powders prepared by flame spraying, fluid bed reactions, and a conventional spray dried technique were deposited on ceramic substrates by arc plasma spraying. The deposition rate was dependent upon the powder preparation technique. The magnetic properties evaluated were temperature coefficient, the real part of the permeability tensor, coercive force, and squareness ratio. It was noted that the squareness ratio of arc plasma deposited ferrite was substantially higher than for the same composition conventionally densified. The arc current and the distance from the arc plasma gun to the substrate influenced the values of temperature coefficient, permeability tensor, and coercive force. Measurements of saturation magnetization and resistivity of the deposited ferrite were also made, and the reproducibility of the arc plasma was evaluated. Possible mechanisms for some of the observed phenomena are discussed.
Preparation of Garnet Films by Sputtering
Three different sputtering approaches are described for the synthesis of garnet films in the thickness range of 0–4 μ. The experimental requirements for producing single‐phase, polycrystalline GdIG films are described in some detail, especially in the rf sputtering mode. Unexpectedly large systematic variations in the unit lattice parameter of the garnet structure as a function of film thickness are reported. Possible causes for these systematic structural changes are discussed.