There is some confusion in the radar community on the handling of phase noise in radar because current definitions give rise to divergent integrals. It is shown that the spectrum of a phase noise modulated signal rather than the spectrum of the phase noise modulating function is the applicable function for coherent radar system design. A heuristic model is proposed to derive the finite power signal spectrum from the infinite power phase spectrum. The well-known phase delay differencing function that is used to weigh the base-band phase noise before integration is also discussed and applied to typical spectra to obtain well behaved analytical descriptions of phase noise that lead to convergent integrals for the autocorrelation and noise power.