SPACE-WAVE CHARACTERISTICS OF MILLIMETER-WAVE GUIDES AND DEVELOPMENT OF LEAKY-WAVE ANTENNAS WITH HIGH PERFORMANCE

点击翻译按钮获取中文摘要

The development of leaky millimeter-wave antennas, which is constructed by a metal waveguide or a planar-circuit transmission line, especially a stub-loaded ridge-rectangular waveguide, has been investigated. For designing antennas, we should analyze accurately the leakage properties of the stub-loaded waveguide and so we have first developed an improved mode-matching method suitable to the analysis of the present waveguie that has many singular-field edges. Then the dependence of the structural parameters on the leakage is calculated and a design method for high-performance antennas with low-sidelobe radiation is established. As a design example, an antenna with the Taylor distribution of -30dB sidelobe level has been designed and fabricated. The measurement of its radiation pattern fully proves the effectiveness of the present antenna. But, the FDTD analysis shows that the higher-order channel-guide leaky mode is a little bit excited, together with the desired leaky mode in the propo … More sed guide structure. This fact is not so serious from the viewpoint of the radiation pattern, but is important from the viewpoint of the excitation efficiency.Therefore the structure of the stub-loaded waveguide has been improved, of which the stub portion is installed into the ridge portion. As a result, the single-mode operation has been realized in the improved guide. The design method for a low-sidelobe antenna based on this improved guide has been again established and its effectiveness has been verified experimentally, too. Finally, the array antenna including a feeding circuit has been designed and fabricated. The measured results confirm the usefulness of the array antenna. These results provide the possibility for using the present leaky-wave antenna practically.While as for planar-circuit transmission lines, it is concluded that introducing lateral conductor walls as well as an air layer between the ground plane and the dielectric substrate is very useful for a high-performance leaky-wave antenna. Less