Exploring Nonlinearity in a Radio Frequency Mixer

This study demonstrates a simple yet effective experiment showing the operating principle of a frequency mixer, which serves as a useful tool for exploring nonlinear systems. The experiment utilizes elementary electronic components, as a silicon diode, to generate and mix signals. The signal analysis, including the sum and difference of the input frequencies as well as higher order harmonics, is performed in the frequency domain using a digital oscilloscope via Fourier transform. A theoretical model based on the diode’s nonlinear response, as described by the Shockley equation, is proposed and compared with the experimental data. The model assumes the diode acts as a fast switch and exploits impedance matching between the transmission line and load to derive an expression for the resulting signal. The study also demonstrates a method for evaluating the conversion loss of specific spectral components. Results show excellent agreement between the proposed model and experimental measurements, validating the approach. The setup is simple and effective, making it suitable for educational environments focused on nonlinear circuit behavior and frequency-domain analysis.