This paper presents an 8 x 8 patch array with inband full-duplex capabilities for Ka-band inter-CubeSat links that can be fitted on the surface of a 1U CubeSat. The array can achieve, on average, 50 dB of self-interference cancellation and it exploits an approach of multilevel sequential rotation to achieve a very low axial ratio (< 1 dB) from 25 to 27 GHz. The array is also characterized by a wide matching bandwidth from 24.5 to 27.5 GHz and can achieve a gain higher than 20 dBi.