Research And Design On RF Circuits In Smart Antenna System

This paper deals with the process of microwave circuit design, or RF block in smart antenna system.Firstly the background, history and trends of the research of smart antenna technology are introduced, along with the base theory and related knowledge of the technology.The author pays much attention to the problem of RF circuits design in smart antenna system. In chapter one, the function and components of RF block in smart antenna are discussed, and the block schematic of RF circuit in smart antenna system at 3.95GHz and 1.9GHz is analyzed.The author's main research work is focused on the design of LNA, Mixer and DRO in smart antenna at 3.95GHz, and LNA in smart antenna at 1.9GHz. The principles and design process of these schematics are analyzed.Low Noise Amplifier using FET is adopted in the RF block of smart antenna both at 3.95GHz and at 1.9GHz. In the design process of LNA, the author applies genetic algorithm in the optimization of gain and noise figure. Some of the adjustment and improvement in genetic algorithm are taken according to the LNA design problem and satisfying result is obtained.Finally, some photographs of circuit boards and the measurement data are provided.