European minor constituent radiometer: A new millimeter wave receiver for atmospheric research

EMCOR is a heterodyne receiver for the frequency range of 201 to 210 GHz. I t has been designed for ground-based measurements of various minor constitu ents of the stratosphere involved in ozone chemistry. Since the aim was the detection of faint spectral lines, a superconducting tunnel junction has b een chosen as mixer element and special care has been taken in developing t he calibration unit of the system. The front-end is completed by a quasi-op tical system, a solid state local oscillator with electronic tuning and a H EMT pre-amplifier. In the back-end an acousto-optical spectrometer is emplo yed to analyse the signal. A PC controls the whole system. The instrument h as been installed at a high mountain site in the Swiss Alps.