The simulated surface current distribution is shown
in Fig. 2(b), where it is clear that antiparallel current
exists on the double U-shaped structure, forming
a current loop which contributes to the magnetic response.
The figure further illustrates the resonance
absorption mechanism. The absorption band of the
above-mentioned structure of MA is very narrow and
the full width at half maximum (FWHM) bandwidth
is about 0.9 GHz.