A new topology of a low-power F-band reflection amplifier for active reflectarrays is proposed and demonstrated using a CMOS fully depleted silicon-on-insulator 28-nm process. The design enables frequency response and center frequency tuning, as well as phase control of the reflected signal. The chip consumes a core area of only $90\times 80~\mu\text{m}^{2}$ and is incorporated into a $2\times 2$ printed reflectarray antenna, implementing the first co-polarized active reflectarray. Such implementation enables, for the first time, active reflectarrays with dual polarization ability, which can be used for full-duplex links, as well as polarization diversity applications. Design considerations for a stable reflection amplifier, as well as measurement results of the reflection amplifier and reflectarray, are presented in this paper. Variable stable gain of 5–25 dB at the frequency range of 106–127 GHz was achieved, with noise figure of 10.5–11.7 dB. The total power consumption was 6–20 mW, depending on the chosen frequency response. An active antenna gain of 28 dBi was measured for the $2\times 2$ reflectarray.