UKMMN Metamaterial Picture Competition 2022

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Image credit: Shiyu Zhang

A broadband dual circularly polarized (dual-CP)reflectarray based on three-dimensional (3D) printed dielectric materials is presented. A novel 3D dielectric arrayelement that enables the broadband linearly polarization (LP) to CP transformation is proposed. The unit cell consists oftwo orthogonal dielectric cuboids, which adjust the phases ofthe two orthogonal LP waves independently and then combinethem into a CP wave. The innovative unit cell design providesan extra degree of freedom in varying the geometries of thearray elements in all three dimensions, which enables us to independently control the phases of the two LP waves. This maintains an equal amplitude and 90? phase difference condition across the entire reflectarray surface, realizing a broadbandand high gain LP-CP reflectarray. The reflectarray is able to provide bothleft-hand circular polarization (LHCP) and right-hand circular polarization (RHCP), with just an LP feed. The measurements demostrate the maximum realized gain and directivity at 34 GHz are measured as 27.9 dBi and 28.1 dBi, respectively. The measured 3-dB gain bandwidth and aperture efficiency are 30% and up to 38%, respectively. More importantly, a broad 3-dB axial ratio (AR) bandwidth greater than 40% has been achieved for both LHCP and RHCP, covering almost the entire frequency band of interest, ranging from 26 to40 GHz.

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