Wideband Circularly Polarized Microstrip Array Antennas Based On SP Feed Network

Antenna is a wireless device to receive and transmit electromagnetic waves,which is always at the forefront of radio frequency system,and high performance antenna is one of the key technologies to improve the quality of space communication.Today,antennas are used in many aspects of life,such as global positioning system?GPS?,mobile communications,electronic toll collection systems?ETC?,radio frequency identification?RFID?,and so on.Meanwhile,antennas are also used in military heavyweights,which plays a vital role in maintaining national security.With the continuous improvement of wireless communication quality,the antenna technology of circular polarization,wideband,high gain,and miniaturization has been attracted increasingly attention.The main reason is that compared with the linear polarization antenna,the circular polarization one has the characteristics of rotatory orthogonality,which can receive the electromagnetic wave in arbitrary polarization form,and the radiation wave can be received by the arbitrary polarization antenna.Compared with narrowband system,wideband has higher transmission speed,stronger anti-multipath interference ability and lower resource occupancy.The high gain antenna has stronger directivity and stronger receiving/transmitting capability.Because microstrip antenna has advantages of light weight,small size,easy to integrate and realize circular polarization,and so on,it has been paid extensive attention and research.Therefore,circular polarization wideband and high-gain microstrip antenna is more competitive by the virtue of its many advantages,so it can develop rapidly and become one of the research focuses.Combining with the actual situation,in this thesis two kinds of microstrip antennas with wide axial ratio beamwidth antenna and wideband high gain circular polarization microstrip array antennas are designed and analyzed.Firstly,the research background and significance are introduced,and the theories of circular polarized microstrip antenna and microstrip array antenna are briefly introduced.Secondly,two kinds antenna elements are designed,one is a wide-axis ratio beamwidth microstrip antenna element with a axial ratio beamwidth of 230°,and another is a wideband quasi-Yagi microstrip antenna element with a bandwidth of 19.2%and a peak gain of 10.1 dB.The radiation mechanism of two elements are studied,and the parameters are analyzed.Then,a compact wideband sequential-phase?SP?feed network with a size of 0.61?₀×0.61?₀×0.011?₀??₀ is natural wavelength?is designed,and its working principle and performance parameters are studied and analyzed.Finally,two microstrip array antennas of novel structures based on SP feed network are designed for C-band applications which are based on the designed elements and feed network.One is a wideband right-handed circular polarization rectangular microstrip array antenna,and the measured results of it shows that the bandwidth is 43.9%,the 3 dB axial ratio bandwidth is 40%,the average cross-polarization ratio is 15 dB,and the peak gain is 9.9 dB;And the other is a wideband left-handed circular polarization quasi-Yagi microstrip array antenna,with a bandwidth of 58.8%,a axial ratio beamwidth of-100°⁷0°,and a peak gain of 20.88 dB.Also the radiation mechanism of these two array antennas are studied and the influence of their parameters on the performance are analyzed.Several kinds designed antennas are processed,and tested in the microwave darkroomof Thirty-nine Research Institute of China Electric Science.The measured results are in good agreement with the simulated results,which verify the rationality of the designs.