Dual Circularly-Polarized Septum Antenna Array Based on an Air-Filled Dual-Mode Feeding Network
Chunli Dong, Yang You, Shuhao Shen, Tianxiang Jin, Jun Xu, Jifu Huang, Yunlong Lu
Abstract
This communication proposes a dual circularly polarized (CP) antenna array based on a septum polarizer using an air-filled dual-mode feeding network. A simple layer of 1-to-4 circular cavities is covered with septum polarizers to combat the grating lobes. The full-corporate feeding network is achieved by using a dual-mode transmission line, thereby combining the transmission of both TEM-mode [excited by HW suspension line (HWSL)] and TE10-mode [excited by hollow waveguide (HW)] in one group of feeding network. This helps to decrease the feeding network complexity. New miniaturized dual-mode separators are inserted between the radiating structure and the dual-mode feeding network to connect them in a limited space so that the low complexity dual CPs can be achieved. An <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$8\times8$ </tex-math></inline-formula> array prototype is fabricated and measured to demonstrate this design. Experimental results present that an overlap bandwidth of 17.4% (18–21.4 GHz) (considering <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\vert \text{S}11\vert < -10$ </tex-math></inline-formula> dB, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\vert \text{S}22\vert < -10$ </tex-math></inline-formula> dB, and AR < 3 dB) is obtained with no grating lobes. Moreover, the peak gain in the same frequency range is up to 26.6 dBic, while the aperture efficiency including antenna efficiency is higher than 69%.