Atacama Pathfinder EXperiment APEX
SHeFI receivers
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APEX-2 receiver (SHeFI 345 GHz band)

Mixer Assembly

APEX-2 Mixer Assembly The SHeFI APEX Band 2 mixer is based on SIS mixers and used sideband rejection (2SB) scheme. Following the success of the APEX-2A receiver, the same type of mixer design is used. In this design the middle piece made of two symmetric parts (split-block technique) and comprises the RF 90° waveguide hybrid and LO division scheme with LO injection directional waveguide couplers using novel on-substrate coupling elements.
The figure shows details of the SFeHI B2 Mixer assembly consisting of the mixers, the middle piece, the IF amplifiers, 3 dB IF hybrid, IF isolators, IF amplifiers (2-stage GaAs HEMT, designed by GARD), LO and RF optical components all integrated on a single bracket and, provided it is necessary, could be removed from the dewar as a single package.


The receiver is characterized by its capabilities and performance. Please find the corresponding information below:

Calibration Plan

The calibration plan for APEX-2 comprises regular observations of a set of spectral line calibrators at frequencies accesible for this receivers.

Comparison Spectra

For a set of frequently used spectral lines, we have a database of comparison spectra from some sources that are widely used as line calibrators. Plots of these spectra can be accessed either through the database interface, or in a table on a static web page.

Spectral Line Catalog

We maintain a system line catalog for APEX-2 which contains frequently (and also not so frequently) used spectral lines in the tuning range.