Network analyzer concept based on quadrature demodulation

Actual paper describes the theoretical approach of a network analyzer using quadrature demodulation as part of a software defined radio. The main idea is strictly connected with the extraction of phase difference and amplitude information for further processing in a microcontroller unit. The system contains variable frequency sine wave quadrature oscillators for frequency sweeping, double balanced active mixers and a microcontroller unit. The analyzer is able to calculate the complex impedance of an unknown network as well as the S parameters and reflection coefficient.