A Novel Reflectarray Unit Based on Mandelbrot Fractal Geometry with Different Degrees and Iteration Numbers

This paper proposes a novel reflectarray unit based on the Mandelbrot-set geometries with a degree from 2 to 6 and an iteration number from 3 to 6. Extensive simulations and analyses with different sizes, degrees, and iteration numbers are conducted for the unit. The results show that the proposed reflectarray unit can achieve a phase shift of more than 360 degree in multiple operation bands from 15-25 GHz while the dimensions of the unit are all within the operating wavelength, indicating that the proposed unit is very suitable for the design of multiple-input multiple-output (MIMO) antennas in the millimeter-wave communications.