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.