Horn Layout
Schematic diagram of the different types of RF channels
| Type | HEMT, cooled |
|---|---|
| Channels | 12 (4 via V/F converters) |
| Receiver Noise Temperature | 18 K - 24 K (about 55 K System Noise Temperature) |
| Frequency Range | 30 – 34 GHz |
| Bandwidth RF-Filters | 30 – 34 GHz |
| Polarization | LHC/RHC, linear (see Horn Layout) |
| Calibration | Noise Diode Transmitter optically coupled |
| Feed | 7 Secondary Focus Horns (Corrugated Horns) |
| IF | None, direct detection principle for continuum only |
| Oscillators | None |
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