This study provides explicit mathematical formulations for the bistatic scattering coefficient from a randomly rough surface with a complex relative permittivity based on the following analytic models: small perturbation model (SPM), physical optics model (PO), and Kirchhoff approximation model (KA). Then it addresses the two shortcomings associated with each of the three models: i) limited applicability domain, and ii) null predicted values for the cross polarized bistatic scattering coefficients within plane of incidence. The plane of incidence contains both backscattering direction and forward (specular reflection) direction which are of interest to the spectrum community.