A New UTD Based Time-Domain Solution for UWB Diffraction in 3-D Environments

Abstract

In this paper, a new time-domain (TD) solution is proposed for analyzing the diffraction of ultra wideband (UWB) signals in three dimensional (3-D) scenarios. In this sense, the solution is based on uniform theory of diffraction (UTD) where the diffraction has been considered by obstacles like 3-D wedge and building. The TD solution is derived with the help of frequency-domain (FD) diffraction coefficient existing in the literature that can be used for arbitrary positions of transmitter (Tx) and receiver (Rx). Considering soft and hard polarizations, the TD expressions are obtained for both amplitude diffraction (i.e., single diffraction) and slope diffraction (i.e., double diffraction). The accuracy of the proposed solution is confirmed by comparing the TD results with the rigorous Maliuzhinets solution and also with the numerical inverse fast Fourier transform (IFFT) of the corresponding FD results. The results are shown for diffraction by objects made up of perfectly electrical conducing (PEC) and dielectric materials. It is obserevd that the TD solution exhibits symetery and reciprocity property and thus can predict the diffracted field for any arbitrary position of Tx and Rx. The generalized behavior of the TD solution is confirmed by employing different kinds of excitation pulses at the Tx. Channel impulse response (CIR) is also studied to analyze the pulse shape distortion. Finally it is shown that the proposed TD solution is computationally more efficient than the FD solution.