Electrical standards of measurement. Part 3: Submillimetre-wave measurements and standards

In the submillimetre-wave region (100GHz¿10THz), standards are not so well established as at lower frequencies. New measurement techniques are being developed and are finding application in a variety of technological fields with a consequent growth in the need for standards. This part of the paper starts by reviewing recent developments of sources, detectors and measurement systems based on Fourier-transform spectrometry. Standards of frequency have been set up using stabilised lasers, and standards of power and energy have been developed. A number of applications of submillitre-wave measurement techniques are discussed, including redetermination of the speed of light, measurement of the electrical properties of materials, environmental standards for pollution in the stratosphere, and plasma diagnosis for research on fusion reactors.