Isotropic conversion loss as a measure of quasi-optical mixer efficiency

Conversion loss is an important practical measure of conventional mixer performance, but the usual definition of conversion loss is often inconvenient and inadequate when applied to quasi-optical mixers with integrated antennas. We herein define a new quantity called isotropic conversion loss (Liso) which not only characterizes quasi-optical mixers with greater accuracy, but is also easier to measure in the laboratory. Experimental results from tests of two different mixers demonstrate the utility of the new measure Liso.