Impact of antennas on practical UWB signals

This paper explores the impact of antennas on the waveform distortion of UWB signals from a new perspective. In the past significant attention was paid to waveform distortion of sub-nanosecond baseband pulses with bandwidths spanning over multiple GHz. However, practical UWB systems operate with signals of significantly lower bandwidth - 500 MHz - 1 GHz. Henceforth, this paper explores the extent of waveform distortion as a function of bandwidth. This is performed theoretically for an ideal electrically small antenna and empirically for practical UWB antennas. It is shown that for practical signal bandwidths the pulse distortion is negligible even for simple practical antennas. This removes the need for complex optimizations. The signal distortion and the knowledge of surface current distribution are linked. This enables us to qualitatively estimate pulse distortion and to understand the limitations and goals of optimization procedures in antenna design.