This dissertation discusses the development of the beamforming antenna systems as a scaled model for customized RFID systems. In this work, an Fabry-Perot Cavity (FPC) antenna system consisting of a single source and frequency selective surface (FSS) is proposed (chapter 2) and investigated. Since the FPC antenna system removes complicated feedline mechanism in array antenna system, it gains high interest to provide higher directivity/gain. Different FSS unit cell geometry and sources are combined in the FPC system and corresponding effect on the FPC system performance is parametrically and comparatively studied and discussed (chapter 3). The CPW feedline behavior and energy leakage of the FPC system are characterized and technique to mitigate them is presented (chapter 4). Microfluids are integrated into the FPC system to offer either tuning/switching capability of the antenna or near-field beam-splitting with FSS (chapter 5). Lastly, efficiency enhancement of the FPC antenna system using FSS subarray is studied.