| Nowadays, the emerging of ultra wide-band (UWB) technology for high-speed indoor wireless communication has attracted worldwide attention. With the merits of high data rate, low system cost and multipath immunity, compared with general narrow band system, UWB has became one of the most competitive and promising technology in the future. The radiation of short duration signals or ultra wide-band signals makes antenna design a crucial part in the overall UWB system development.In this paper, the development of UWB technology is firstly introduced, and then some basic antenna parameters have been reviewed as well as the UWB requirements. Secondly, the broadband characteristics of the wide-angle biconical antenna have been researched and parameters such as input impedance and VSWR are resolved. Simulations are carried out by CST microwave studio to demonstrate validity of the results. An asymptotic conical monopole antenna which is applicable to UWB is designed by using the equivalent charge distribution method and the Chu-harrington limit. Thirdly, two kinds of planar patch antennas fed by microstrip line proposed in literatures are simulated. Changes in performance under different antenna parameters are discussed. Finally, the finite difference time domain (FDTD) method which is suitable for UWB antenna simulation is introduced. The discussion includes difference scheme, numeric characteristic as well as PML based on uniaxial anisotropic material. Simulations are carried out for the biconical antenna to illustrate validity of FDTD. |
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