Circularly Polarized Antennas Based On Substrate Integrated Waveguige

The substrate integrated waveguide(SIW) structures have been presented in recent years, which can be fabricated in planar form using a standard printed circuit board(PCB) or low-temperature co- ?red ceramic(LTCC). As a good substitute of conventional rectangular waveguides, SIWs are very suitable for the design of micro- millimeter wave system. In the meanwhile, circularly polarized antennas have been studied for many years and widely used to solve the problems of polarization mismatch and multi-path interference in Wireless Communication Field. Consequently, how to use the substrate integrated waveguide technology to design circularly polarized antennas fabricated on SIW has become an important issue for many scientists. In this thesis we investigate the mode behavior of rectangular, circular and hexagonal SIWs, and have successfully developed several circularly polarized antennas based on the half mode substrate integrated waveguide(HMSIW) and corrugated substrate integrated waveguide(CSIW) technologies.Firstly, the radiation pattern, directivity, gain, input impedance, standing wave and loss of antenna are systematically illustrated in this paper. And the basic principles of substrate integrated waveguide, equivalent analysis method, resonant characteristics of resonant cavity with different shapes are analyzed thoroughly. Then it comes to a conclusion about how to design a circularly polarized antenna.Secondly, three types of circularly polarized antennas based on dual- mode hexagonal SIW cavity are achieved, the two preceding antennas are right-handed circular polarization(RHCP) and left-handed circular polarization(LHCP), respectively. The third type is a novel circularly polarized antenna based on the corrugated substrate integrated waveguide(CSIW) technology, its simulated gain at the boresight direction reachs 10.31 d B. Although the size of this antenna is a little bigger than the aforementioned two, the novel method gives us new insight to design s ubstrate integrated waveguide resonant cavity.Thirdly, half mode substrate integrated waveguide(HMSIW) technology is introduced to realize three low profile, single fed and circularly polarized(CP) cavity antennas. The shapes of resonant cavity for the three antennas are semi-circle, semi-rectangle, semi- hexagon, respectively. From the simulated and empirical data, it comes to this conclusion: the application of the HMSIW technology can improve the bandwith, with the impedance bandwith enhanced to 5% and the axial ratio bandwidth got to more than 1%.Finally, two types of double side radia nt circularly polarized antennas are achieved. These two antennas verify the validity of realizing double side radiant by using the substrate integrated waveguide technology and the design of multilayer structure. The design of these two antennas can avoid the radiation loss in the single layer structure and then improve the radiation efficiency. And in the meanwhile, these two antennas can be used as bidirectional antennas.