Wideband Circularly Polarized Septum Antenna Array With Ridge Gap Waveguide Feeding Network for Wireless Application

Abstract

A full corporate feeding <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$8\times $ </tex-math></inline-formula> 8 circularly polarized (CP) planar antenna array using septum antenna elements for millimeter-wave (mmWave) frequency band applications is reported. Widebands for both the impedance and axial ratio (AR) bandwidths and high efficiency are guaranteed by the antenna array attributed to septum elements and feeding network based on the metal ridge gap waveguide (RGW). For the analyzing <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2\times $ </tex-math></inline-formula> 2 sub-array containing a feeding structure, simulated results show that the impedance bandwidth ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\vert S_{11}\vert &lt; -10$ </tex-math></inline-formula> dB) of 31.4%, AR bandwidth (AR < 3 dB) of 32.6%, and maximum gain of 29.2 dBic are realized. For the practical fabricated 8 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> 8 antenna array prototype, measured results reveal that its impedance bandwidth ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\vert S_{11}\vert &lt; -10$ </tex-math></inline-formula> dB) is 31.5%, overlap AR bandwidth (AR < 3 dB) is 33.1%, and maximum measured gain value is 28.4 dBic with a maximum aperture efficiency of 85%. With such performances, the proposed CP antenna array would be a promising candidate for mmWave communication systems.