Nonlinear modeling of tunnel diode detectors

We investigate the sensitivity and nonlinear properties of a tunnel diode microwave detector as functions of the input power and the load impedance presented at the detector's output. We estimate the systematic error associated with using a linear calibration model to estimate received power and, hence, brightness temperature from the nonlinear voltage-power transfer function of the detector. One estimate is provided by the two-tone method, the other by an empirical regression spline method