Designs for bifrequency and bidirectional AMC surfaces

The AMC behavior of a reflecting surface is mainly related to the frequency where the 0deg crossing in the phase of its reflection coefficient takes place. This frequency gives the resonant frequency that characterizes the AMC surface. Two different designs of AMC surfaces showing quite different properties are presented in this communication. A first design proves the AMC behavior using metallic tubes with slotted square profile instead of the typical periodic arrangement of strips printed on a dielectric substrate; and the latter, shows the AMC performance of an artificial material when the electromagnetic waves impinge on its opposite faces.