| Recent years, with the development of ultra-wideband wireless communicationsystems, UWB antenna attracted great attention among authors and various feasibledesigns of ultra-wideband antennas are reported. As the terminal device of theultra-wideband wireless communication systems, the UWB antenna must meet higherperformance requirements, such as small size, low profile, and wide impendencebandwidth， steady-going radiation patterns, high gain in the frequency-domainperformance. Moreover, it is necessary to study the UWB antenna’s time domaincharacteristic, for the UWB antenna transmits and receives the short pulse. At the sametime, the UWB antenna with band-notched characteristic is used to avoid interferencebetween the UWB band and existed narrow band for wireless communication systems.Therefore, UWB band-notched antennas are proposed in this thesis for UWBcommunication systems.The main contents of the dissertation are summarized as following:Firstly, two simple and compact micro-strip line-fed printed monopole UWBantennas with multiple band-notched characteristics for UWB communication areproposed. One is a stacked-circular planar antenna with triple band-notchedcharacteristics, and the other is an elliptical planar antenna with quadrupleband-notched characteristics. In the design of the two kinds of planar antennas,defected ground structure with slot and rounded-corner of the ground are used tochange the current distribution, which creates an extra resonant frequency, and henceimproves the impedance bandwidth at the upper frequency. By adding a simpleT-shaped parasitic strip on the bottom side and an L-shaped branch in thestacked-circular radiating patch, the antenna is no responsive at desired frequencywhich realizes triple band-notched operations. For quadruple band-notched antenna, byembedding a pair of Z-shaped slots and an ao-shaped slot on the elliptical radiatingpatch and adding an shan-shaped strip on the back layer, the quadruple band-notchedcharacteristics is acquired. Then, this paper proposed a double-exponential-curve antipodal vivaldi antennafor radar system. In the band of0.6~3GHz, the return loss is less than-10dB. In orderto avoid interference, by adding an F-shaped branch in the radiating patch, aband-notch function in810-960MHz is obtained. The branch parameters are alsostudied in detail. At the same time, to study the time-domain characteristic, thetransceiver setup is proposed, through CST Microwave Studio software. Thetransceiver setup consists of an antenna as transmitter and36virtual probes asreceivers. The virtual probes are located in both (H-) and (E-) planes at theta=00,100,200,300,400,…,3600and phi=00,100,200,300,400,…,3600and the received probesignals for the UWB Vivaldi antenna and UWB Vivaldi signal band-notched antenna attheta=00,300,600,900are listed. Then, the normalized H-and E-plane peak-amplitudepatterns for the two Vivaldi antennas are obtained by depicting the all received probesignals. Finally, we use two Vivaldi antennas compose a transmitting and receivingsystem, for studying the transfer functions, group delay, as well as, the pulsewaveforms of the receiving antenna, so do the two Vivaldi antennas with band-notchedcharacteristic. |
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