Experimental equipment and techniques for a study of millimetre-wave propagation

Apparatus has been developed to study the characteristics of radio-wave propagation in the region of the oxygen absorption band (wavelengths, 4¿6mm). The sources of power were crystal harmonic generators and pulse and c.w. magnetrons, and the design of crystal detectors and mixers is described. The construction of waveguide components for this wavelength range is discussed, together with equipment for measurement of impedance, frequency, power and attenuation. For most of the propagation measurements, a transmitter with an output of a few microwatts was used, together with a calibrated superheterodyne receiver. Communication tests were carried out with a pulse-frequency-modulated magnetron transmitter. Measurements of the oxygen attenuation over paths of a few kilometres have been made at a number of wavelengths in the absorption band. Measurements over sea have given values of the reflection coefficient of the sea surface. These results are summarized and discussed briefly.