Radiation Characteristics Analysis of Tri-Polarized Dipole Antenna

Abstract

Dual-polarized antenna involves polarization purity degradation and power gain loss when scanning at wide angles. Aiming at mitigating above limitations, we exploit tri-polarized antenna for better radiation characteristics in this paper. We formulate the beam pattern synthesis problem of a single tripolarized 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 multi-polarized antenna, especially at wide scan angles. And 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.