© The Institution of Electronic and Radio Engineers
Coatings of hexagonal ferrites on a wire antenna reduce its back-scattering radar cross-sections (r.c.s.) at microwave frequencies without causing significant deterioration of its radiation efficiency at the h.f. and v.h. communication bands. The back-scattering r.c.s. of an infinitely long conducting cylinder coated with a multilayer of hexagonal ferrites is derived and the result modified to take account of the finite length of a monopole antenna. Computed results for layered coatingsare presented to demonstrate the improvement in the microwave absorption bandwidth obtainable for a given coating thickness. It follows that the technique is best applied with all material and geometric parameters having tapered distribution and the ferrimagnetic resonances staggered over the required frequency band. Finally, the theory is illustrated by the measurement of the backscattering losses of a v.h.f. ferrite-coated antenna in the microwave frequency band (for both TM and TE polarizations of the incident waves) and its radiation performance at the v.h.f. range
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