Research On Wide Beam Circular Polarization Antenna

Circularly polarized antenna can receive any linearly polarized wave and circularly polarized wave with the same rotation, and it can eliminate the signal Faraday rotation effect caused by the ionosphere. So it is widely used in satellite communication, navigation and positioning systems. The satellite navigation and positioning systems require antenna having broad beamwidth to ensure that there is sufficient gain at the low elevation. Therefore, in this thesis, the broad beamwidth circularly polarized antenna is deep studied. And two circular patch antennas with broad beamwidth are designed. The research contents are as follows:Firstly, the research status and progress of broad beamwidth circularly polarized antenna are summarized, and the working mechanism and common methods of broading the HPBW and ARBW are discussed. Then the microstrip antenna is seriously analyzed. Simulated single-fed circular patch circularly polarized antenna has the performance that its angle range of axial ratio less than 3dB is-100°～100°. It indicates that the microstrip antenna has a unique advantage on realizing broad beamwidth circularly polarized radiation.Secondly, a circular patch antenna loaded double metal parasitic rings (strips) of a multi-layer structure with broad beamwidth and circular polarization is proposed. Based on the single-fed patch antenna, parasitic strips are loaded on the same layer to broad the beamwidth. Also, a parasitic ring is loaded on another substrate to improve the circular polarization performance within the beam. A broad beamwidth circularly polarized antenna at 2.49GHz has been developed. It has the HPBW of 156°, and 3dB-ARBW more than 190°.Thirdly, a circular patch antenna loaded parasitic ring (strips) and monopole array of a single-layer with broad beamwidth and circular polarization is proposed. The ring (strips) and monopole array respectively leads the two orthogonal components of the main patch radiation fields. Therefore, the circular polarization performance can’t be affected while the beamwidth is broadened. A broad beamwidth circularly polarized antenna at 2.49GHz has been designed. It has the HPBW of 160°, and 3dB-ARBW of 180°.In this thesis, two excellent broad beamwidth circularly polarized antennas are designed by loading different parasitic elements. They both have the advantages of simple structure, light weight, easy to make, low cost and have good practical engineering value.