Submillimeter-wave radiometers have traditionally been built by packaging each chip with a distinct function separately, and then combining the packaged chips to form subsystems. Instead of packaging one chip at a time, the radiometer on a chip (ROC) integrates whole wafers together to provide a robust, extremely powerful way of making submillimeter receivers that provide vertically integrated functionality. By integrating at the wafer level, customizing the interconnects, and planarizing the transmission media, it is possible to create a lightweight assembly performing the function of several pieces in a more conventional radiometer. This represents a greater than 50-fold decrease in both volume and mass. The act of combining the individual radiometer functions into a sequence of chips will also improve inter-component matching and reduce the loss associated with the power combining that accompanies today’s radiometers. Most of the gain fluctuations in present- day radiometers are the result of thermal gradients. By reducing the size and mass of the radiometer, the thermal gradients are reduced, thus also reducing their effect on thermal stability. This results in greater measurement stability.
With a size reduction of this magnitude, ROCs will be able to be used in balloons, landers, rovers, and any other place where a complete remote chemical laboratory might be required.