This paper describes the behavior of a microwave external modulation link com- posed of: optical and radio frequency sources, Mach-Zehnder modulator (MZ), optical fiber and photodetector. The electro-optical circuit modulates the RF signals and transmits them to the detector through the optical fiber. The main contribution of this paper lies on the different approach to the system analysis; we consider an off-quadrature biased MZM. By extending the mathematical model found in the literature for the case of different bias voltages, we compute a few performance parameters of the system like Gain and SFDR. For computing those parameters we use a custom made program written in the MATLAB environment. In addition to the system’s characterization and insights on its off-quadrature operation, another contribution of this article is the model validation. We assembled the electro-optical circuit and measured some performance parameters for different values of bias voltages. By comparing the experimental results with the theoretical ones, we validated the model. Finally, we also consider the applications for microwave signals distribution by optical fiber links.