Information Loss in a Nonideal Electromagnetic Channel

The modification of the quantum states of various electromagnetic signals caused by their transmission through a channel having nonunity transmission factor is considered on the basis of a simple model. The quantity of information transmitted along such a channel by various ensembles of signals is evaluated. The efficiencies of various transmission methods, evaluated as a function of the radiation power, bandwidth, and center frequency for a channel with large attenuation, are compared.