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 sprayed C-band lithium ferrite phase shifters
The arc plasma spraying (APS) technology has demonstrated the capability of being economical in the fabrication of non-reciprocal ferrite phase shifter elements. It has been possible to arc plasma spray a C-band element in less than 10 minutes using a commercial spray dried lithium ferrite powder. This paper discusses the material properties (coercive force, remanence, and microwave loss) of the deposited lithium ferrite and the device performance (differential phase shift and insertion loss) of arc plasma fabricated phase shifter elements. The effects of stresses, generated by a mismatch of thermal coefficient of expansion between the ferrite and the dielectric are also discussed.
The incidence of dead and dying fish in the Moray Firth, September 1963
Dead and dying fish were reported from the Moray Firth during a period of 15 days in September 1963. The initial mortalities were in the inner Firth, but they later spread outwards, especially eastwards along the southern shores of the Firth. Mass mortalities of the lugworm (Arenicola marina) also occurred in Scottish waters in 1962 and 1963, and at Balintorein Easter Ross fish and lugworm mortalities were contemporary.