Research And Design Of Novel Planar Spiral Antenna

Antennas are key components of any wireless communication system. They are devices that allow for the transfer of a signal in a wired system to electromagnetic wave. With the rapid development of wireless communication, both compact size and good radiation performance are required while design antennas. Planar spiral antennas have the advantages of great performance on circular polarization and stable radiation performance. They are ideal choice in broadband satellite communication services, mobile systems, ground based and airborne direction finding systems. Designing spiral antennas that have simple structure, small size and easily integrated with RF circuits is necessary.This paper is committed to study planar spiral antennas with the operating frequency range of ultra-wideband(3.1-10.6GHz). On the basis of summarizing and analyzing techniques proposed in recent years, this paper tries to design spiral antennas with better radiation performance and compact size. The main research work is summarized as follows:Firstly, the paper analyzes the differences between spiral antennas with different spiral arms. And a new spiral curve is designed, which can be used to define a new kind of spiral antenna. The tightness of the spiral arm can be tuned with different parameters. The design process of this spiral edge is given.Secondly, a new spiral antenna is proposed. The developed antenna has improved axial ratio and shorted arm length. The results reveal that the developed spiral antenna has noticeable improved axial ratio at low frequencies compared with Archimedean spiral antenna, and the problem of axial ratio degradation of power spiral antenna is also solved. The differences between these antennas are analyzed.A spiral antenna with integrated parallel-plane feeding structure is proposed. The conventional feeding structure for planar spiral antennas is situated in the center of the spiral and extends into the third dimension. The vertical feeding structure always has a significantly long length, inconsistent with the requirement of the low-profile spiral antenna geometry. The spiral antenna and a Dyson-style balun have been integrated into a multi-layer structure. The resulting structure maintains the typical radiation behavior and broadband operation of spiral antennas without the vertical balun. The overall size of the spiral antenna is largely reduced.