Orthogonal Polarization Agile Planar Array Antenna

Acknowledgement I would especially like to express my most sincere thanks to my advisor, Professor Masayoshi Aikawa, for his invaluable guidance, advice, encouragement and support throughout the completion of my study and this thesis. I would also like to express my appreciation to the members of my thesis committee, Professor Kohei Arai, Professor Tatsuya Furukawa, Associate Professor Sumio Fukai and Associate Professor Shinichi Sasaki for their kind assistance and valuable instruction. Special appreciation is also designated to Lecturer Takayuki Tanaka, Assistant Professor Eisuke Nishiyama and Mr. Tasuku Uechi for their kind assistance. Then I want to thank to all my lab-mates for their kindness, direct and indirect support and making these past years of working together an enjoyable time. Last but not least, a very big thank you to my beloved parents and friends in China, for their genuine support and constant encouragement they have bestowed upon me throughout my study in Japan. Abstract In the recent years, along with the rapid progress of wireless communication technology, wireless equipments have been widely applied to various practical fields such as Global Positioning System (GPS), Wireless Local Networking Systems, and wireless access systems and so on. The main requirements of these wireless equipments are the better performance, low cost and small size. Due to various functionalities as well as lightness, low profile and easy fabrication properties, microstrip planar antennas are well suited for any wireless equipment. As an important requirement of planar antennas, the polarization agility technique is a typical and good candidate in advanced wireless communication systems because of its promising capability. In this study, therefore, a novel three conductive layers 2×2 ring-slot array antenna is designed and utilized to realize the simultaneous use of the orthogonal linear polarizations. Due to the use of the characteristics of the ring-slot array antenna and features of the both-sided MIC technology, excellent performances such as broad-band, good isolation, and better cross polarization suppression are obtained. For the symmetrical antenna structure, two orthogonal linear polarizations can be realized with same radiation pattern and same polarization performance. In addition, the antenna design is very simple, and the array antenna is easy to fabricate. Using the characteristics of the ring-slot array antenna mentioned above, a novel circular polarization ring-slot array antenna with simultaneous use of the orthogonal polarizations is proposed. By integrating a broad-band 90 degrees hybrid circuit, the array antenna can radiate two kinds of circular …