Electromagnetic Channel Statistics for Continuous-Aperture Array (CAPA) Systems

The channel statistics of a continuous-aperture array (CAPA)-based channel are analyzed using its continuous electromagnetic (EM) properties.The received signal-tonoise ratio (SNR) is discussed under isotropic scattering conditions.Using Landau's theorem, the eigenvalues of the autocorrelation of the EM fading channel are shown to exhibit a step-like behavior.Building on this, closed-form expressions for the probability distribution of the SNR and the average channel capacity are derived.Numerical results are provided to validate the accuracy of the derivations.