6 cm (4.85 GHz, Secondary Focus) Receiver


Receiver Data

TypeHEMT, cooled
Receiver Noise Temperature9 K
Frequency Range4.6 - 5.1 GHz
Bandwidth RF-Filters4.6 - 5.1 GHz
CalibrationNoise Diode
VTO: yes
Phasecal for VLBI: yes
Broadband Polarimeter2 Broadband Polarimeters
Phaseshifterin channel B and D
Feed2 x Horn A 009
1. IF2360 - 2860 MHz
1. OscillatorULO1 (x5) or LO (7.460 GHz)
2. IF500 - 1000 MHz (VLBA)
- or -
100 - 200 MHz (Narrowband,MKIII)
2. OscillatorULO2 (x4)
(VLBA: 3360 MHz, NB: 2700 MHz)

Block Diagram


This is a 4 channel system with cooled HEMT preamplifiers. It has been constructed for sensitive Continuum, VLBI and Pulsar observations. It is permanently installed in the secondary focus cabin.
The frontend has 2 identical dewars, each comprising one horn, a cooled directional coupler, circular (RHC and LHC) transducer and 2 HEMT amplifiers etc.

The Broadband Polarimeters are placed at the frontend, because the system has a large bandwidth. The detected signals are converted to pulses (V/F-Converter), digitally transferred to the receiver room and counted in a digital backend. The signals are converted back to analog signals for control and adjustment purposes in the receiver room.

To allow VLBI and Pulsar observations two IF-Signals (RHC and LHC of one feed) are available at the receiver room either in the range 500 to 1000 MHz (VLBA and Pulsar) or 100 to 200 MHz (MK III or Narrowband observing).