The design, construction and measurement of a quasi-optical multiplexer and antenna for space-borne atmospheric measurements from 56 to 425 GHz

We have developed a low-loss quasi-optical multiplexer (QOM) for future space-based meteorological radiometry covering nearly a decade of frequencies - from 54 GHz to 425 GHz. We have shown that very low loss can be combined with high channel co-alignment in a compact package, suitable for surviving the launch environment. The QOM uses shallow angle low-loss dichroic plates (DCP´s) allowing polarization diversity and ultra-Gaussian horn feeds to minimize both component size and standing waves. The losses in the multiplexer were measured using a novel double path S₁₁ VNA technique, and beam co-alignment was verified by scanning with a wideband detector.