| Toward the development trends that the communication equipment should be more compact,wideband,portable and intelligent,the requirements for antenna design become increasingly strict.Wideband antenna offers enough bandwidth,good polarization characteristics and stable radiation characteristics provided that suitable volume space is allocated to the antenna.Therefore,how to design a miniaturization wideband antenna with stable radiation characteristics has become an important research topic.In addition,the operating bandwidth of the common phased array antenna is limited by both the bandwidth of the antenna elements and the scanning angle controlled by the distance between adjacent elements.So,it is difficult to satisfy the requirements for high resolution and multi-target tracking in modern radar technology.However,the wideband wide-angle scanning antenna array based on the miniaturization wideband antenna can increase the operating bandwidth significantly in the phased array radar.Up to now,UWB antenna has demonstrated a lot of prototypes.Among all of these,log-periodic antenna and Vivaldi antenna gets more attention because of their compact size,low cost,simple structure and ease of fabrication.Meanwhile,Vivaldi antenna is also used in phased array antenna due to its good Gaussian pulse response.In this thesis,the design theories and improvement measures of above mentioned two types of antenna are discussed.Two miniaturization wideband antenna,including a 7.5:1 miniaturization printed log-periodic dipole antenna and a 22.5:1 miniaturization antipodal Vivaldi antenna is designed.Finally,a 4:1 bandwidth miniaturization antipodal Vivaldi antenna with resistance and parasitic patch loading based on the mutual coupling effects is designed for a 8×8 phased array antenna,whose max scanning angle is ±45°. |
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