Radiation Characteristics Analysis of Tri-Polarized Dipole Antenna

摘要

Dual-polarized antenna involves polarization purity degradation and power gain loss when scanning at wide angles. Aiming at mitigating the above limitations, we exploit a tri-polarized antenna for better radiation characteristics in this letter. We formulate the beampattern synthesis problem of a single tri-polarized dipole antenna in a convex form, and solve it with the Lagrange multiplier method. When circular polarization is synthesized, we show that degree-of-freedom increase improves the polarization purity and power gain of the multipolarized antenna, especially at wide scan angles. We further find that, using the infinite current sheet model, the radiation pattern synthesized by tri-polarized antenna is the same with the optimally oriented dual-polarized antenna—the dual-polarized antenna is mechanically rotated to be oriented normally to the scanning direction. We discuss the situation when linear polarization is synthesized. We show that the power gain is increased corresponding to scan angle, while the polarization purity is not improved obviously.