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****Abstract.
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Electromagnetic model of a controllable or non-controllable
frequency-selective screen is developed. Corresponding boundary problem of
diffraction is solved by integral equation method. The model can be used to
optimize geometrical dimensions of the flat frequency-selective surfaces (FSS)
taking into account the presence of control devices or films, it can be useful
when calculating properties of different screens based on such FSS. The results
of numerical calculations of the frequency and angular performance of FSS with
control devices and films are discussed.

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****Key words:
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frequency selective surfaces, controllable transparency, screen, antenna,
integral equation.

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