3D-printed cavity backed crossed dipole antenna for high gain, wideband circular polarization in sub-6 GHz

Abstract

Triple-arm crossed dipole antenna (CPDA) backed by 3D printed cavity exhibits high gain over wideband axial ratio for sub-6 GHz applications is presented. To improve peak gain and axial ratio bandwidth performance, multiple radiating arms are introduced. The arms are cascaded using vacant quarter rings to obtain circular polarization. Unlike the conventional CPDAs that yield single circular polarized (CP) wave, two CP waves produced by double-arm or triple-arm CPDAs enhances overall gain performance across wideband axial ratio. The length and orientation of the multiple arms in the CPDA determine the maximum current generated on the crossed dipole antenna, resulting in an improved gain since two CP waves are combined in the free space. To further increase boresight gain, 3D printed cavity is placed beneath the triple-arm CPDA. Unbalance impedance line presented in this work extends impedance bandwidth of the triple-arm CPDA to cover 3-dB axial ratio bandwidth. For validation purpose, a prototype was fabricated and measured. The measurement results demonstrate that the triple-arm CPDA has a boresight gain of 8.91–11.7 dBic within 3-dB axial ratio bandwidth of 51.4% (3.25–5.5 GHz). The proposed antenna produces a stable gain within sub-6 GHz bands.