Circularly Polarized Waveguide Slot Antenna Research

Waveguide slot antenna is widely used in many fields such as radar systems, ground-based receive station, satellite communication due to its own advantages of high gain, high efficiency and compact structure. In applications of antenna, polarization is especially important.In this thesis, about how to realize circularly polarization design for waveguide slot antenna, many studies have been done as follows.Firstly, based on stating the design principles of waveguide slot antenna in detail, two schemes on circularly polarized waveguide slot antenna design were proposed for application of dual circularly polarized shared-aperture antennas. One scheme is circularly polarized ridge waveguide slot antenna, in which an circularly polarizer is added to a waveguide slot. The other scheme to realize circular polarization of the waveguide slot antenna is appending microstrip to waveguide slot antenna.Secondly, circularly polarized ridge waveguide slot antenna have been investigated. On the basis of longitudinal slot cutting on the broadside of waveguide, appended polarized waveguide to realize circularly polarized radiation. Ridge waveguide is adopted both for feed waveguide and polarized waveguide to reduce the size. Radiation characteristics of unit is analyzed in-depth. Then a1X10circularly polarized linear array is designed at lOGHz.A gain of17dB has been achieved with a side lobe level of25dB and the bandwidth with axial ratio less than3dB is3.3%.The antenna has a good axial ratio bandwidth with amplitude control easily and small size. It is suitable for realizing high performance dual polarized shared-aperture antenna.Thirdly, this paper proposed circularly polarized unit design of microstrip-appended waveguide slot. Microstrip patch is appended on the broadside of general waveguide slot. The energy couples to microstrip patch from feed waveguide. Circularly polarization radiation is achieved through microstrip patch with flexible design characteristics. Simulation and analysis for circularly polarized unit has been carried out in detail. The feasibility of design is verified. And proposed appending two units scheme to improve radiation efficiency. The antenna possess many advantages such as high efficiency in accordance with waveguide slot antenna, design flexibility like microstrip patch and convenience of manufacture, which suggests good prospects.