An Improved Total Hemispherical Radiometer

Abstract

Modification of the Beckman and Whitley total hemispherical radiometer is described. In the improved model, the thermojunction embedded in the sensing plate is replaced by three embedded thermistors connected to associated external electrical circuitry. The modification automatically compensates for temperature -caused variations In output of the sensor thermopile and adds an emf proportional to the back radiation of the upper surface of the sensing plate (σT4. Calculated and measured values of circuit performance are found to be within 2 per cent of the desired values over a temperature range of O?50C.