INFORMATION CAPACITY AND QUANTUM EFFECTS IN PROPAGATION CIRCUITS
MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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Attempt is made to establish an upper bound on the information capacity of an electromagnetic wave propagation circuit between two apertures when quantum effects come into play. We first discuss the specifications of a signal, and find that we can associate approximately BT quantities with a signal of bandwidth B and duration T, and that the energy associated with these quantities must differ by at least one quantum of energy. We then consider radiative attenuation loss within the framework of quantum theory and find that the radiative attenuation introduces a random noise in the circuit which is analogous to partition tube noise. With the channel matrix determined, we discuss the problem of evaluating the channel capacity under average and peak power constraints. Due to mathematical difficulties we are only able to establish the channel capacity explicitly when the radiative losses become extreme. In this limiting case-as a byproduct-we also find that the best encoding procedure is a binary on-off system.