Ultra Wide Band Antennas

Preface

Ultra wide band (UWB) has received a great amount of interest since the decision by the US Federal Communications Commission (FCC) in February 2002 authorizing the emission of very low power spectral density in a bandwidth going from 3.1 to 10.6 GHz. This technique of radio transmission consists of using signals whose spectrum is spread out over a wideband of frequencies, typically from about 500 MHz to several GHz. It was formerly used for military and radar applications, then transposed a few years ago to telecommunications, thus causing a growing interest within the scientific community and industry. This spectral availability makes it possible to consider the wideband communications and also leads to a fine space resolution for the radars. However, the current restrictions of the regulatory agencies on the emission power level limit the range of the UWB communications to a few meters for high data rates and up to a few hundred meters for low data rates. UWB technology thus seems naturally well positioned for short range communications (WLAN, WPAN), offering an alternative at the same time of low cost and low consumption to the existing standards in these networks.

The acronym UWB gathers two standardized but distinct technologies today. The first is founded on the emission of impulses of very short duration; this is the mono-band or impulse radio approach. The second approach is based on the use of multiple simultaneous carriers where the bandwidth is subdivided into ...