International Symposium on Antennas and Propagation
A Septum Polarizer by Inserting Additional Stubs for its Applications in the CP Horn Antennas
His-Tseng Chou, Shih-Chung Tuan, Wen-Wen Lee,
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A polarizer structure is studied, which is motivated in designing multi-beam reflector antennas [1,2] with circularly polarized (CP) radiations for multi-satellite digital TV receptions as illustrated in Figure 1. These have narrow beam separations due to crowded satellite placements, and results in insufficient spaces to place isolated feed horns. Co-structured horns are required and degrade their radiation performances. A septum polarizer is investigated and used to compensate the deficiency of the horns’ radiations. Due to its symmetry, an ordinary septum polarizer is not able to compensate the radiation deficiency of both right-handed (RH) and left-handed (LH) CPs simultaneously because the cross-polarized component of a linearly excited horn plays an opposite role for RHCP and LHCP. This paper investigates the possibility of resolving this problem by inserting stubs inside the polarizer to create unequal ARs. Thus several configurations shown in Figure 2 are numerically investigated to exhibit their physical behaviors in influencing the polarizer’s characteristics. In particular, characteristics of return loss (RL), axial ratio (AR) and phase difference (PD) will be examined as described in the following sections.