Microwave frequency doubler based on a quadrature couplers and baluns

The article deals with mathematical model of microwave frequency doubler based on a quadrature couplers, baluns and in-phase power combiners. The mathematical model based on the nonlinear large signal scattering parameters. Expressions for input reflection coefficient, output reflection coefficient, parasitic harmonics level and desired signal level are derived. The influence of amplitude and phase imbalance of quadrature couplers, baluns and active devices on the reflection coefficient, power of desired and parasitic output waves was analyzed.