Ultra Wide Band Antennas

Chapter 6

Antenna-Channel Joint Effects in UWB ¹

6.1. Introduction

The ultra wide band (UWB) signals undergo a series of deformations between the output of the emission stage and the input of the reception stage of a radio link. These deformations are due to the antennas at the two ends of the link, but also to the radio channel because of the multiple events (diffraction, reflections, absorptions, etc.) which the waves undergo between the two antennas. They appear in the temporal domain as well as in the spectral domain and take all the more importance as the spectral width is large, or in a dual way, as the signals simultaneously contain fast and slow variations. The waveform of the emitted signal thus plays a big role in the deformations which it can undergo, as do the antennas and the propagation environment. The shape of the received signal is affected differently according to the various cases, and this very much influences the quality of detection. It is obvious that the architecture of the transmitter, through the emitted waveform, and that of the receiver, through the nature of the detector, impact the performance of the radio link. This results in a larger complexity than for a narrow band-based system, for which the antenna-channel block behaves like a simple dephasing attenuator. This complexity in the frequency or temporal domains makes the serialization of the antenna-channel-antenna blocks more difficult and less intuitive, and does not allow us to immediately evaluate ...