The theoretical foundations of coupled, nonlinear oscillator arrays as applied to beam forming have, almost exclusively, presumed the unit cells are well described by a Van der Pol oscillator model. In the past, a “weak” association was made between the spectral output of the differential-pair oscillator and that of an ideal Van der Pol oscillator. By applying the Method of Multiple Scales to the Van der Pol dynamical equations, one finds that only odd order harmonics are present. Moreover, one can determine the key Van der Pol parameters (i.e., the amplitude parameter, p, and nonlinearity parameter, μ) through the power contained in the first and third harmonics.