Study Of Wideband Electro-magnetic Dipole Composite Antenna Excited By Microstrip-Slot Transition

With the development of wireless communication technology, the indoor wireless coverage is becoming a topic. However, the coverage in high-rise buildings, underground parking and tunnels is always a hard task to wireless network designers. In order to coverage or enhance the signal power in these areas, the indoor distribution system was provided. The existing antenna used in indoor distribution system is not compatible with the wireless communication for its complex structure and limited bandwidth. Therefore, it is essential to design a wideband unidirectional antenna with simple structure and high performance. In this thesis, a high-performance broadband unidirectional antenna with simple structure is proposed and fabricated. The main content of this thesis is organized as followed:1. At first, the research background of indoor distribution system and electro-magnetic dipole composite antenna is introduced. The basic antenna theory is illustrated. The method and steps of electromagnetic simulation software IE3 D and HFSS is introduced briefly.2. On the theory of electro-magnetic composite antenna, a novel unidirectional antenna fed by the microstrip-slot transition is designed. The design principle is verified by the HFSS.3. On the basis of former design, the feed section of antenna is improved by off-centered microstrip slot. Then, bend the dipole, a “aperture-dipole” composite element is obtained. By these means, more resonant modes can be excited. Finally, the antenna prototypes are fabricated and measured by the Agilent’s 8720 ET vector network analyzer and the Satimo Starlab system. The measured impedance bandwidth of two antennas are covering from 4.3 GHz to 8.1 GHz and from 1.88 to 3.72 GHz. The antennas have stable and unidirectional radiation pattern.