A novel and useful THz radiation detector comprising a suspended dipole antenna and a plurality of reflectors for achieving low thermal mass and high electrical performance. The reflectors used in the antenna do not physical contact the dipole element and are used to shape the radiation pattern in similar fashion as obtained by well-known Yagi-Uda reflectors. The dipole element is connected directly to a load resister for generating heat which is sensed by a sensing transistor. The lack of a mechanical connection to the dipole antenna element prevents any increase in the thermal capacitance of the antenna.