A three-cavity refractometer and associated telemetry equipment

The paper describes the construction and performance of a microwave, spaced-cavity refractometer designed for the measurement of the small-scale variations of refractive index in the lower atmosphere. The instrument has been used on a captive balloon at heights up to 2¿5 km with telemetry equipment transmitting, to a ground station, information on variations in refractive index, temperature, wind speed and pressure.