Ultra-Wideband Printed Antennas Design

Abstract

On February 14, 2002, the Federal Communications Commission (FCC) of the United States adopted the First Report and Order that permitted the commercial operation of ultra wideband (UWB) technology (FCC, 2002). The FCC allocated a bandwidth of 7.5GHz, i.e. from 3.1GHz to 10.6GHz, to unlicensed use for UWB applications. Ultra Wideband is defined as any communication technology that occupies greater than 500 MHz of bandwidth, or greater than 25% of the operating center frequency. The UWB spectral mask was defined to allow a spectral density of -41.3 dBm / MHz throughout the UWB frequency band. UWB technology has several advantages that are the reasons that make it very attractive for consumer communications applications; it has been regarded as one of the most promising wireless technologies that have a capability of revolutionizing high data rate transmission and enables the personal area networking industry leading to new innovations and greater quality of services to the end users. Ultra wideband systems present several advantages i) have potentially low complexity and low cost; ii) have noise-like signal which makes unintended detection quite difficult, because of their low average transmission power, UWB communications systems have an inherent immunity to detection and interception; and low power consumption; iii) are resistant to severe multipath and jamming; and iiii) have very good time domain resolution allowing for location and tracking applications. Also UWB systems can penetrate effectively through different materials. The low frequencies included in the broad range of the UWB frequency band have long wavelengths, which allow UWB signals to penetrate into a variety of materials, such as walls. This advantage makes UWB technology favourable for through the wall communications, ground penetrating radar, body implant wireless communications... Since UWB has an ultra wide frequency bandwidth, it can achieve huge capacity as high as hundreds of Mbps or even several Gbps with distances of 1 to 10 meters (Oppermann, 2004). UWB systems operate at extremely low power transmission levels, and hence UWB signals do not cause significant interference to other wireless systems. The UWB technology is one of the viable candidates for short-range indoor radio communication systems supporting very high bit rates services and applications. In this chapter, different aspects and challenges of UWB antennas design are discussed. And compact printed disc monopole antenna (3.5 to 31.9 GHz) for current and future ultra wideband applications will be presented.