Characterisation of attenuation at low THz frequencies in radar sensors

Intensive research and development activity on low-terahertz (0.1-1 THz) electronics, including recent advances in monolithic microwave integrated circuit (MMIC) fabrication, indicate that THz radar might become feasible in the coming decade, at a reasonable cost. Low-THz radar sensors are promising short range sensing for mobile robotics, automotive industry and avionics industries. Physically small antenna sizes are sufficiently electrically large to provide high angular resolutions. As a first step, the influence of contamination on the sensor radome is investigated for complex practical outdoor environments, by taking various weather (rain, snow, fog, etc.) and road conditions (mud, water, oil, etc.) into account. New measurement technique for characterising low-THz signal attenuation in different materials which may cover the radome is discussed, as a pre-requisite for the development of such systems. The method proposed in this paper is based on the ratio of the signals reflected from the reference target propagate through air and a signal is transmitted through the material under test. Attenuation of different material has been characterised at two different frequencies, 150 GHz and 300 GHz.