9 mm 7 Beam (30 - 34 GHz, Secondary Focus) Receiver


Receiver Data

TypeHEMT, cooled
Channels12 (4 via V/F converters)
Receiver Noise Temperature18 K - 24 K (about 55 K System Noise Temperature)
Frequency Range30 – 34 GHz
Bandwidth RF-Filters30 – 34 GHz
PolarizationLHC/RHC, linear (see Horn Layout)
CalibrationNoise Diode Transmitter optically coupled
Feed7 Secondary Focus Horns
(Corrugated Horns)
IFNone, direct detection principle for continuum only

The receiver is a pseudocorrelation design similar to those used for WMAP / PLANCK that offers suppression of the 1/f noise resulting from gain fluctuations which are inherent to cryogenic InP HEMTs. There will be three polarimetry pixels available, 2 circular, 1 linear polarized. Another two pixels will be total power LCP, each referenced to an internal cold waveguide load whose temperature is accurately measured synchronously with the data from the RF detectors. Finally there is beam switch implemented in hardware with two horns differenced by means of a waveguide magic tee. In figure 2 a schematic sketch of the different types of RF channels that are implemented in the receiver is given. Since the receiver is laid out as a direct detection receiver, no mixing to an IF at a few GHz is carried out, all processing down to the final direct detection step is done at 30 - 34 GHz.

Horn Layout

Schematic diagram of the different types of RF channels