A THz radiation detector comprising a plurality of antenna arms separated from a suspended platform by an isolating thermal air gap. The detector functions to concentrate THz radiation energy into the smaller suspended MEMS platform (e.g., membrane) upon which a thermal sensor element is located. The THz photon energy is converted into electrical energy by means of a pixilated antenna using capacitive coupling in order to couple this focused energy across the thermally isolated air gap and onto the suspended membrane on which the thermal sensor is located.