A high-gain wideband antenna employing novel partial reflective surfaces

In this dissertation, different partially reflective surfaces (PRS) are investigated to improve the gain and bandwidth of a Fabry–Perot cavity (FPC) antenna for wireless local-area network (WLAN) and vehicle-to-vehicle (V2V) communication applications. Each of the proposed PRSs has the phase of a reflection coefficient that increases with frequency. This property of the PRS is required for a broadband characteristic of the FPC antenna, which is desirable for the intended applications. A U-shaped microstrip patch antenna (MPA) with a parasitic rectangular patch is used as a feed antenna. It is designed for operation in the WLAN and V2V frequency bands. The first PRS is a simple structure consisting of two layers of dielectric slabs of equal thickness and electric permittivity separated by a small air gap. The second PRS consists of two thin layers of periodic structures of unit cells based on a cross-dipole slot etched on a square patch on a dielectric substrate. The third design is a novel PRS based on a compact microstrip resonant cell (CMRC). The proposed PRSs were first designed and analyzed using the bi-characteristic transmission line (BCITL) models and the equivalent circuit models, and then further optimized using the full-wave simulation of unit cells with appropriate periodic boundary conditions. Subsequently, the entire structure of the FPC antenna, which consists of the feed antenna and the designed PRS, was analyzed using the full-wave simulation software to calculate its characteristics. The FPC antennas with three different proposed PRS were fabricated and tested to validate the simulation results. The measurement results show that the first FPC antenna achieves a maximum broadside gain of 10.43 dBi, which is 4 dB higher than that of the feed antenna, and a 3-dB gain bandwidth of 15.25%, which coincides with the impedance bandwidth. The second FPC antenna offers a maximum broadside gain of 12.3 dBi and a wider gain bandwidth of 18.25%, outperforming the first antenna. Finally, the third FPC antenna has a maximum broadside gain of 10.18 dBi and a 3-dB gain bandwidth of 15.72%. Although its performance is no better than that of the first two antennas, the overall height is lower because its PRS consists of only a single layer.