| With the widespread applications of the wireless communication systems, variouskinds of information transmission technologies are developing rapidly. As one of themost important components in the systems, the performance of the antennas is directlyrelated to the communication quality of the whole system. The wirelesscommunication systems demand the antenna developing corresponding wideband,multiband, circular polarized and high gain technique. The microstrip slot antennas arebecoming a hot spot of the designs and applications, because of their low profiles, easyfabrication and easy integration characteristics.In this thesis, based on the research on the related papers at home and abroad,wideband antenna with notched band, multi-band antennas and circular polarizedantenna are studied in depth, and the implementation and design principles of themicrostrip slot antenna are mainly summarized. Then in accordance with therequirements of communication systems, an ultra-wideband (UWB) antenna with dualband-notched functions, a microstrip slot antenna to achieve triple-frequency operationfor WLAN/WiMAX applications and a broadband circular polarized high gainmicrostrip slot antenna are presented in this thesis. The main content of this thesisincludes the following three parts:In the first part, the wide band technologies with notched band functions areanalyzed and synthesized. A novel compact CPW-fed planar monopole ultra-wideband(UWB) antenna with3.5/5.4GHz dual band-notched functions is proposed. Tominimize the electromagnetic interferences between WiMAX/WLAN and UWB, a pairof inverted U-shaped slots is etched in the center of the radiation element. Details ofthe antenna design and experimental results are presented and discussed. The antennais fabricated and shows good characteristics, and the measured and simulated resultsshow good agreement.In the second part, the technologies to realize the multi-band antenna are introducedand summarized. A crossed oval-ring microstrip slot antenna to achievetriple-frequency operation for WLAN/WiMAX applications is proposed. The antennaprototype is fabricated and the characteristics are experimentally verified. Themeasured impedance bandwidths for triple operating bands can reach840/670/940MHz with return losses larger than10dB. In addition, good radiation characteristicswith moderate peak gains are obtained and the measured and simulated results show good agreement.In the third part, the technologies to realize the broadband and circular polarizedantenna are introduced and summarized. A broadband circular polarized microstrippatch antenna which is coupled by two H-shaped slot is presented. The antenna showsgood characteristics at18GHz. In addition, the technology of dielectric lens isintroduced and the proper dielectric lens for the project is designed. Based on theantenna above, we design a planar array which is composed of four elements. At last,the designed broadband circular polarized high gain microstrip lens antenna showsgood characteristics and meets the project requirements. |
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