| Summary: | 博士 === 國立交通大學 === 電信工程系所 === 97 === This thesis proposes two types of leaky-wave antennas. One type is on a cylindrical substrates and the other type is on a planar substrate. The well-known full-wave method, spectral domain approach, is applied to investigate the propagation characteristics of leaky modes on both configurations.
First, a cylindrical microstrip leaky-wave antenna is analyzed and designed. From the numerical results of computed propagation constants, it has the same characteristics as those of the planar ones. With the similar aperture-couple feeding structures used in planar microstrip leaky-wave antennas, the first higher order leaky mode is successfully excited. In addition, a high gain and wideband leaky-wave antenna is implemented.
Moreover, the first higher leaky modes on two cylindrical structures, slotted coaxial lines and cylindrical coplanar waveguides, are also studied. The effects of different parameters are shown and can be used to decide the operating frequency band of leaky-wave antennas. Two design examples are presented to show the performance of these types of leaky-wave antennas.
Second, the relationship between the first higher order leaky mode of a slotline and surface wave mode on a grounded dielectric slab is presented. A slotline leaky-wave antenna fed by a wideband microstrip-to-CPW transition is demonstrated.
Finally, an inverted-T leaky-wave antenna is introduced. It has the same properties as the single-conductor strip leaky-wave antennas, such as wide bandwidth and fixed mainbeams. Compared to the single-conductor strip antennas, the broadband phase inverter is not needed and the antenna width is halved. Therefore, the realization of inverted-T antennas is easier than that of single-conductor strip ones.
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