Upgrade of EMIR's Band 3 and Band 4 Mixers for the IRAM 30 m Telescope

The Eight Mixer Receiver (EMIR) is a multi-band millimeter wave receiver installed since 2009 at the 30 m telescope of the Institut de Radio Astronomie Millimetrique (IRAM) at Pico Veleta in Spain. In autumn 2011, Band 3 and Band 4 will be equipped with state-of-the-art sideband-separating mixers with 8 GHz intermediate frequency (IF) bandwidth. For Band 3 a side- band-separating mixer has been developed within the European project AMSTAR+ in order to replace the currently employed single-sideband mixer. The new mixer has an IF bandwidth twice as large as the current one, and two sidebands, thus doubling the continuum sensitivity of the receiver. The mixer currently installed in Band 4 will simply be upgraded to 8 GHz IF bandwidth by changing its IF components.