Study On High - Efficiency And High Efficiency Circularly Polarized Waveguide Slot Antenna

Antennas with high gain are always the goal that researchers spare no effort to pursue in the fields of radar, communication, remote sensing and space technology. Since circularly polarized antennas have the advantage of strong anti-interference ability, they get more and more attentions. Meanwhile, waveguide slot antennas have advantages of high gain, high efficiency and compact structure, in this thesis, about how to realize the radiation of electromagnetic with high gain, high efficiency and circular polarization using traditional waveguide slot antenna, many studies have been done as follows.First, review the research history and present situation of circularly polarized slotted waveguide array antenna.Secondly, a novel circularly polarized patch array fed by slotted waveguide is proposed by loading a split truncated patch array on a longitude slotted waveguide antenna. Optimized circular polarization is achieved with a split truncated patch flexibly. Improved bandwidth and efficiency are obtained by utilizing the feeding waveguide. Parametric study on a circularly polarized element at 10.5GHz is conducted to provide an instructive design guideline. Then a 1-by-10 circularly polarized array has been developed. This antenna combines the high efficiency of slotted waveguide antenna with the flexibly designing and easily fabricating of patch, which indicated good prospects.Thirdly, a novel cross-slotted circularly polarized waveguide slot array is designed. The element is composed by three sections including the feeding waveguide, the thin square cavity and the cross slots cutting on the cavity. The coupling slot receives a linear polarized electromagnetic signal which is perpendicular to the slot and passes these signals to the cavity section. By controlling the length of the cross slots, two orthogonal modes with the same magnitude and 90 phase difference are excited, which is perpendicular to the cross slots, respectively. Then a 16-by-16 planar array with simulated impedance bandwidth of 2.3%, AR bandwidth of 2%, gain of 33.2dB is designed. The aperture efficiency reaches to 88.3%, which achieving the goal of high gain and high efficiency.