  Resonant coupling of coplanar waveguides is explored by wrapping proximate
shorted ends of the waveguides with micron size ferromagnetic Co90Ta5Zr5 tubes.
Ferromagnetic resonance and up to 7 outer surface modes are identified.
Experimental results for these contorted rectangular tubes are in good
agreement with micromagnetic simulations and model calculations of
magnetostatic modes for an elliptical ferromagnetic tube. These results
indicate that the modes are largely determined by tube topology and dimensions
but less so by the detailed shape.
