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This article presents a terahertz (THz) wideband transmitarray antenna with wide-angle beam steering for intersatellite communications. A new design method is developed for beam steering/multibeam transmitarrays based on feed displacement. The phase compensations on the transmitarray aperture are theoretically analysed for two steered symmetrical beams from two conjugate foci in an arbitrary azimuthal plane. Then, the focus for a boresight beam is investigated to minimise the corresponding phase errors. A circular feed track is produced with the three foci, enabling wide-angle and low-scanning-loss beam steering by changing the focal point. A unit cell model based on the Huygens metasurface is designed with only one substrate layer, capable of continuously tuning the phase in a 360° range with low transmission losses. The THz transmitarray prototype is engineered with the developed beam-steering method and unit cells. The prototype is experimentally verified with a wideband stable beam-steering performance from 180 GHz to 220 GHz in a wide angular range of ±48°. The measured minimal scanning loss is only 1.4 dB. The measured 3-dB gain bandwidth of the boresight beam is 19.1%.