| In recent years, with the development of wireless communication technology,higher performance antennas such as frequency, polarization, reconfigurable pattern, arerequired in the communication systems. Traditional techniques are extremely limited toachieve these requirements. Metamaterial has brought a new way to designreconfigurable antenna for its high flexibility to control electromagnetic waves.This dissertation focuses on the metmaterial in reconfigurable antenna designs.Based on the urgent need for polarization and pattern reconfigurable antenna, a rotatablereflectarray beam-steering antenna and a low profile polarization reconfigurable dipolehave been design using the phase modulation characteristics of metmaterial.The research mainly includes two parts:In the first part, a beam-steering reflectarray antenna is reported. A novel rotatablereflectarray to achieve beam steering is proposed. This rotatable reflectarray consists ofa planar phase shifting (PSS) and a microstrip reflcetarray, and the beam steering can berealized by rotating two kinds of plane along their normal axis. A Ku-bandbeam-steering reflectarray antenna operating at12.5GHz have been fabricated andtested based on this theory. The measuring results show that the designed antennapossesses continuous scanning capability in a range of360°in Azimuth plane and±41°in zenith plane.The second part presents a low profile polarization reconfigurable dipole antenna.This antenna is achieved by utilizing tunable electromagnetic band-gap (EBG) structureground plane to replace the perfect electric conductor (PEC) ground plane. By tuningthe loaded PIN diodes through bias voltage circuit, the anisotropic and isotropic featuresof the EBG can be transformed. Experimental results show that the tunable EBGstructure can make the dipole antenna work at three different polarized states, includingright-handed circular polarization, left-handed circular polarization and linearlypolarized waves. |
PDF Full Text Request