I. Introduction
In THIS PAPER, statistical models for the input impedance of a linear antenna in an electrically large cavity are developed [1]. Cases where modes have overlapping spectra, and the antenna impedance approaches the free space value [2], as well as separate discrete spectra [3], [4] are both considered. The behavior of the impedance and its extreme values are useful in determining the transmission and reception characteristics of an antenna and practical bounds for these quantities. An electrically short center driven dipole is treated first by means of a modal series for the cavity field. The statistical properties of the high-frequency cavity field are introduced [7], [10], [11] from which distributions for the impedance are extracted by means of Monte Carlo simulation and asymptotic analysis. These simulations and asymptotic results are compared to measurements in a mode stirred chamber. It is then shown how these results apply to an electrically longer resonant dipole and a wall-mounted monopole antenna. The known enhancement of the field near the cavity wall [24]is found to correspond to the behavior of the field correlation function, which is needed in the treatment of the monopole antenna. Finally, a simplified approach using conservation of power is carried out that yields practically useful formulas for the impedance distributions and extreme values.