Wide-band UHF antenna of circular polarization
Date of Issue2016-08-16
School of Electrical and Electronic Engineering
Ultra high frequency band (UHF) usually refers to the UHF radio waves whose frequency range is from 300 MHz to 3000 MHz, and plays a significant role in modern wireless communication system. Antenna is a key component of modern wireless communication system, which directly influences communication quality. With the development of the society and the modern wireless communication system, wide-band and low-profile antennas of circular polarization are of great demand in many communications systems, such as Radio Frequency Identification (RFID), Unmanned Aerial Vehicle (UAV) and the like. To satisfy the above demand of the development of the modern wireless communication system, this dissertation aims to design a planar UHF antenna that exhibits wide bandwidth, circular polarization, and end-fire radiation. This antenna is a combination of a top-hat monopole Yagi antenna and a printed log-periodic antenna, which are combined with a phase shifter. The antenna is designed and optimized in High Frequency Structure Simulator (HFSS). The main content is as follows: (1) Design of a Yagi antenna of vertical polarization that achieves an extremely low profile and wide bandwidth. This Yagi antenna consists of a driven element, a folded top-hat monopole, and parasitic elements, four top-hat monopoles. (2) Design of a printed log-periodic antenna (PLPDA) which is wide bandwidth and horizontal polarized. Combining these two antennas with a offset phase difference between the Yagi antenna of vertical polarization and the PLPDA can achieve circular polarization. (3) Design of a phase shifter to achieve the required phase difference. (4) Optimizing of the final design, and check its radiation parameters. Discuss the characteristics of the final design.