In this paper, a new time-domain (TD) three-dimensional dyadic diffraction coefficient is proposed for ultra wideband (UWB) signals with arbitrary polarization and oblique incidence. Simulation results are presented for diffraction by a single wedge, double wedge and building scenario with consecutive diffractions. An excellent agreement of the proposed TD solution with the inverse fast Fourier transform (IFFT) of the corresponding exact frequency-domain (FD) solution proves the validity of the TD solution. Also it is observed that the TD solution is computationally more efficient than the IFFT–FD method. The presented TD solution can be used to analyze diffracted field for arbitrary polarized UWB signals with oblique incidence.