  This paper presents a very simple analytical model for the design of
Frequency Selective Surfaces based on Complementary Split Ring Resonators
(CSRR) within the microwave range. Simple expressions are provided for the most
important geometrical parameters of the model, yielding an accurate description
of the CSRR resonance frequency and avoiding full-wave numerical simulations.
Besides, a qualitative description of the band-pass filter behavior of these
structures is described, considering its high quality factor Q.
