An ultralow-profile circularly polarized (CP) reflectarray (RA) antenna is presented in this article, based on the variable-rotation technique for beam collimation and scanning. Starting from a conventional split-loop element, a new wideband element is designed having a single conductor layer on a single thin dielectric. The RA element, based on two coupled microstrip loops, exhibits a dual-resonant CP behavior and a stable response over a wide range of incident angles and frequencies. The wideband response is explained through eigenmode and full-wave simulations in an infinite-array environment, by examining the current distributions on the coupled loops. A high-gain 900-element offset-fed RA antenna is designed for CubeSat intersatellite links at 24.6 GHz using the proposed element. A new element rotation procedure is used to determine the required rotation angles, while eliminating phase errors in the RA aperture. The antenna prototype exhibits a 1 dB gain bandwidth of 6.8% and an axial ratio smaller than 1 dB, with the array profile of only 0.042 lambda(0) at 24.6 GHz. The maximum measured antenna gain is 31.5 dBi, which corresponds to a total aperture efficiency of 58%.