Dependence of double-resonance diffraction peculiarities on impedance grating parameters

Summary form only given. We present analysis of (-1, 1) and (-2, 1) resonance diffraction for in-plane geometry at an impedance grating of arbitrary form. The consideration is based on improved results of previous work (Kats and Spevak, 1998; Balakhonova et al., 2001). In the vicinity of close resonance, we provide expansion with respect to small deviations from the unshifted resonance point. We present results in a scaled form that possess universality, and therefore the specific parameters of the grating and surface material define only the position of the resonance and the tails of the resonance curve.