Quasi-planar Broadband Circularly Polarized Microstrip Antenna

Researches on broadband circularly polarized microstrip antenna have been done in this dissertation. With the rapid development of modern wireless communication and the higher requirements of communication quality, antenna module is becoming the critical component in communication systems in order to adapt to variety of applications in ground and satellite communication. Microstrip antenna has been widely used in wireless communication system for its advantages that are compact size, light weight, conformability to mounting hosts and easy integration. It is easy to realize circularly polarized, but its narrow bandwidth property limits its application in wireless communication,and studies on broadening circularly polarized microstrip antenna's bandwidth have practical significance and value.In this dissertation, three aspects, including the basic design theories of helical antennas, the novel microstrip heliacal antenna structures, and the design of heliacal antennas using LTCC technology are research focuses. The major contents are listed as follows:Firstly, summaries of techniques to achieve circularly polarized and broaden bandwidth of microstrip antenna have been done. Method and some new designs of broadband circularly polarized microstrip antenna are introduced and the operating principle of helical antenna working in axial mode is described in detail.Secondly, a novel microstrip helical antenna with broad circularly polarized bandwidth is proposed based on the traditional helical antenna. The helix is realized by connecting stacked multilayer microstrip circular arcs with vertical via holes. Details of the antenna design method and parameter analysis are described. A comparison between simulated and measured results is also presented and discussed. Measure results show that good radiation performance can be achieved. Finally, an improved antenna design to reduce the return loss with a tuning stub is presented.At last, LTCC technique and its application in antenna design are introduced. A new helical antenna design with one third circular arc component is described based on the characteristic of LTCC technique that is easy to fabricate multilayer structure.Simulation results show that good radiation performance can also be obtained and this type of antenna has outstanding advantage in integration application.