  In this paper we theoretically study electromagnetic reflection,
transmission, and scattering properties of periodic and random arrays of
particles which exhibit both electric-mode and magnetic-mode resonances. We
compare the properties of regular and random grids and explain recently
observed dramatic differences in resonance broadening in the electric and
magnetic modes of random arrays. We show that randomness in the particle
positioning influences equally on the scattering loss from both electric and
magnetic dipoles, however, the observed resonance broadening can be very
different depending on the absorption level in different modes as well as on
the average electrical distance between the particles. The theory is
illustrated by an example of a planar metasurface composed of cut-wire pairs.
We show that in this particular case at the magnetic resonance the array
response is almost not affected by positioning randomness due to lower
frequency and higher absorption losses in that mode. The developed model allows
predictions of behavior of random grids based on the knowledge of
polarizabilities of single inclusions.
