Schottky Mixer
There are three types of mixers which can be used for Submillimeter heterodyne receiver, i.e., (1) Schottky (2) Superconductor-Insulator-Superconductor (SIS) and (3) Hot Electron Bolometer (HEB). The Schottky mixer can work at room temperature for the laboratory spectroscopy. It is a metal semiconductor diode made from GaAs semiconductor. The whisker antenna is mechanically contacted to the chip and the diode is mounted in the corner cube structure. The copper corner cube acts as a reflector and helps in enhancing the main lobe of whisker antenna. The radiation is coupled to the diode through whisker efficiently. The output of the mixer is mixing of two incoming signals, i.e., local and source signals. The difference frequency signal known as an Intermediate Frequency (IF) signal is filtered out using a band pass filter.
The Schottky to be used in the present experiment is CMB2 made available from Farran Technology. The input frequency range of the mixer is 600 to 800 GHz and it is optimized at 700 GHz frequency while its the IF of the mixer is 5.52743 GHz with bandwidth of 1 GHz.