Passive mm-wave imaging

Passive millimetre wave night-time imaging systems suffer little attenuation in cloud and light drizzle. There has been considerable advances in semiconductor solid state devices. In particular there are wide bandwidth low noise amplifiers and mixers as well as low cost compact sources such as Impatt and Gunn diodes. These advances have also produced high speed digital computers with large memories making possible sophisticated signal processing and complex theoretical modelling and analysis. The author examines the impact of these developments on passive millimetre wave imaging and shows how the picture quality can be improved and imaging take place in real time