Wideband 3-D Printed All-Metal Reflectarray With Notches for Low-Cost Millimeter-Wave Applications

In this paper, a 3-D printed all-metal reflectarray is presented for millimeter-wave applications. The array has sub-wavelength element spacing, so that the elements are non-resonant. A two-stage notch is etched at the top of the element, which provides multiple degrees of freedom for phase tuning. The phase variation range is more than 360? by changing the height and width of the first stage of the notch. Thanks to the non-resonant property and the two-stage notching, stable phase shift can be maintained in wide frequency range. A reflectarray with 20x20 elements is fabricated by using 3-D printing technique, which has the merits of flexible construction, light weight and low cost. The simulated and measured results on radiation patterns and realized gain are highly consistent. The measured 1-dB gain bandwidth achieves 17.6%, ranging from 31 GHz to 37 GHz. In the whole 1-dB gain bandwidth, the measured aperture efficiency is higher than 47.7%, with a peak efficiency of 53.6% at 31 GHz. The proposed reflectarray has no substrate loss and can provide high aperture efficiency in wide bandwidth.