  The Random Coupling Model (RCM) is a statistical approach for studying the
scattering properties of linear wave chaotic systems in the semi-classical
regime. Its success has been experimentally verified in various over-moded wave
settings, including both microwave and acoustic systems. It is of great
interest to extend its use to nonlinear systems. This paper studies the impact
of a nonlinear port on the measured statistical electromagnetic properties of a
ray-chaotic complex enclosure in the short wavelength limit. A Vector Network
Analyzer is upgraded with a high power option which enables calibrated
scattering (S) parameter measurements up to +43 dBm. By attaching a diode to
the excitation antenna, amplitude-dependent S-parameters are observed. We have
systematically studied how the key components in the RCM are affected by this
nonlinear port, including the radiation impedance, short ray orbit corrections,
and statistical properties. By applying the newly developed radiation
efficiency extension to the RCM, we find that the diode admittance increases
with excitation amplitude. This reduces the amount of power entering the cavity
through the port, so that the diode effectively acts as a protection element.
