Investigation of Wideband Fabry-Pérot Cavity Antennas for Millimeter-Wave Applications

Abstract

This thesis presents a series of wideband Fabry-Pérot Cavity (FPC) antennae with unique electrical characteristics for millimeter-wave applications. Radio signals within millimeter-wave spectra exhibit a high propagation attenuation as a result of extensive atmospheric absorption. For this reason, the wireless communication industry is always searching for high gain and low-cost antennae. FPC antennae have received much attention over the past few years due to their high gain, their low profile and mass, and their fabrication simplicity and cost-saving potential relative to bulky horns or corporate-fed arrays. A significant challenge associated with FPC antenna design is their narrow operating bandwidth. In this thesis, a quasi-parabolic reflector is proposed to extend the bandwidth of FPC antenna at 60 GHz. Based on this proposal, novel techniques are applied to overcome the challenges associated with traditional FPC antennae, such as insufficient gain, fixed radiation direction, limited functionality and low operating frequency.

Our study begins by demonstrating a bandwidth extension method for a millimeter-wave FPC antenna. We propose a novel quasi-parabolic reflector, and by using this structure we show that multiple resonant modes can be excited between the partially reflective surface (PRS) and the proposed ground state of the FPC antenna. Based on this proposed antenna structure, a switched-beam FPC antenna is further designed. Compared with other beam-switching FPC antennae, our proposed antenna exhibits wide band, high gain, and large beam-steering angle characteristics.

Furthermore, we propose a new structure for a PRS which is utilized to realize further gain enhancements for the proposed wideband millimeter-wave FPC antenna. This proposal represents the first attempt to apply a Fresnel zone plate (FZP) to a single-layer PRS, and results in significant gain improvement within a wide operating bandwidth. We further introduce a new structure of polarizer relevant to the design of wideband millimeter-wave circular polarization (CP) FPC antennae. This aspect of our work represents the first attempt to construct a 3D-printed polarizer with an inserted singlelayer PRS, which contributes to the generation of circular polarization while maintaining a high antenna gain.

Finally, a design method for wideband dual-polarized FPC antenna realization at the D band is presented. A feeding source with a novel metallic exciting network is designed on the basis of low-temperature co-fired ceramic (LTCC) technology, and is shown to provide dual-polarized radiation within a wide frequency band. In addition, an LTCC based phase shifting surface (PSS) is designed above the source. The combination of its stepped structure and drilled holes ensures impedance matching and phased control, which contributes to antenna gain enhancement within a wide operating bandwidth.

Date of Award	10 Oct 2019
Original language	English
Awarding Institution	City University of Hong Kong
Supervisor	Hang WONG (Supervisor)