Research On The Leaky-Wave Antennas Based On The Corrugated Substrate Integrated Waveguide

ABSTRACT:Leaky wave antenna is a kind of traveling-wave antennas which has been widely used in engineering applications. In the past design, the leaky-wave antennas have good performances. However, further development and applications of the leaky-wave antennas are restricted due to the disadvantages of the closed waveguide structure (such as large volume, high cost, difficulty to be integrated) and open-planar waveguide structure (such as the undesirable radiation and the cross interference caused by parasitic and surface-wave modes). The substrate integrated waveguide not only inherits the superior transmission performance of the conventional waveguide, but also has a huge odds in the fabrication process of the planar structure. Therefore, the substrate integrated waveguide becomes a hot research topic in recent years rapidly, and it has offered a new opportunity for the development of leaky-wave antennas. And then the advent of a new structure-corrugated substrate integrated waveguide, provides a new research direction for the planar waveguide structure. In this thesis, leaky wave antennas are designed based on the corrugated substrate integrated waveguide. The feasibility of the corrugated substrate integrated waveguide structure used in the antenna design is validated, and the antennas are fabricated and measured. In addition, to solve the problem of high sidelobe level, the designs are optimized to have low sidelobe level in the study. Then the factors which have influences on the sidelobe level are analyzed.The main work and creative points of this thesis can be summarized as follows:1. A novel type of leaky wave antennas with a long straight slot based on the corrugated substrate integrated waveguide has been designed. The impedance characteristics and the radiation characteristics of the slot antenna are studied, and the relationship between the attenuation constant and the offset of the slot has been analyzed. The designed antenna is fabricated and measured. The experimental results are in good agreement with the simulation results. And this kind of leaky wave antenna based on the CSIW uses the microstrips instead of the metal via-holes in the conventional SIW to simplify the measured process.2. A novel type of leaky wave antennas with partially reflecting surface based on the corrugated substrate integrated waveguide has been designed. The impedance characteristics and the radiation characteristics of the PRS antenna are studied, and the relationship between the attenuation constant and the different distance of the partially reflecting surface has been analyzed. The designed antenna is fabricated and measured. The experimental results are in good agreement with the simulation results.3. A new kind of circular-polarized slot array leaky-wave antenna based on the corrugated substrate integrated waveguide is designed. The amplitude and phase on the slot pairs are studied and the8-element circular-polarized antenna is designed. And the impedance characteristic and the radiation characteristic is studied. Broadside vertical radiation can be realized by the proposed design, and a good axis radio bandwidth can be obtained.4. According to the radiation pattern synthesis method, the leaky-wave antenna based on partially reflecting surface structure is designed with the property of low sidelobe level. The influences of the antenna aperture field distribution and the corrugated microstrips on the sidelobe level are analyzed, and then the influences are considered in a further optimization of sidelobe level.