TABLE OF CONTENTS Tadahiko Maeda
Beginning with the importance of antennas in ultra-wideband (UWB) telecommunications for future wireless communications applications, this chapter provides a cohesive vision of the analysis and evaluation of antenna systems over the UWB frequency spectrum. This chapter also covers the basic principles and theoretical and practical technologies required to enable spectral-efficient antenna systems to coexist with other wireless systems, as well as an assessment of the potential structural characteristics of UWB wireless telecommunications systems.
In 2002, the U.S. Federal Communications Commission (FCC) allocated the unlicensed use of UWB frequency spectrums [1]. Three types of UWB system applications that require UWB frequency spectrum include: (1) short-range communication and measurement of peer-to-peer contact both indoors and outdoors at 3.1 to 10.6 GHz; (2) radars that prevent vehicle collisions and detect an object's position and movement with center frequency larger than 24.075 GHz in the 22- to 29-GHz band; and (3) inner-wall surface inspection in medical and underground exploration by radar imaging systems. In particular, UWB systems are gaining attention for short-range communication and measurement applications [in (1) above] because of the possibility of generating extremely short pulses with the simple switching circuit prevalent inside microprocessors; therefore, ultra-broadband antennas have come to play an important role as a key component in the realization of the system.
In short, the FCC's deregulation of the UWB frequency spectrum triggered the accelerated development of antennas capable of covering the entire UWB frequency band.
Such antennas may be divided into several groups...
