A multi-channel electro-magnetic rotary joint has been invented in which one or more electro-magnetic signals can be transmitted simultaneously from a rotating collimator array and a stationary collimator array in air and in other fluids. A metamaterial de-rotating mechanism is positioned in the path between said rotating collimator array and said stationary collimator array, and arranged tier rotation relative to each collimator arrays at a rotary speed equal to one-hall the relative rotational rate between said rotating and stationary collimator arrays.