3.6 cm (8.6 GHz, Secondary Focus) Receiver


Receiver Data

Type HEMT, cooled
Channels 2
Receiver Noise Temperature 4 K
Frequency Range 7.95 - 9.15 GHz
Bandwidth RF-Filters 7.95 - 9.15 GHz
Polarization LHC and RHC
Calibration Noise Diode
Phase Cal for VLBI: yes
Feed Secondary Focus Feed
1. IF 2.2 - 3.2 GHz
1. Oscillator ULO1 (x3) or LO (ca. 5.9 GHz/ 5.646 GHz)
2. IF a. 0 - 1 GHz (VLBI, Spectroscopy)
b. 0.5 - 1 GHz (VLBA)
2. Oscillator ULO2 (x4) 2.2 GHz/ 2.204 GHz

Block Diagram


The 8.6 GHz system is a secondary focus receiver with cooled HEMT amplifiers and a cooled polarization transducer. The system is set up for receiving both circular polarizations. Since the calibration signal is injected through the directional coupler directly following the horn, it is linearly polarized. The feed is fed through the inner part of the 2.3 GHz offset paraboloid feed system to form a S/X-band receiver for VLBI observations.

The receiver is extended to 1.1 GHz instantaneous bandwidth in the VLBI IF. To use the full bandwidth the LOs have to set to the following values:
ULO1 = 941 MHz (x6 = 5.646 MHz)
ULO2 = 551 MHz (x4 = 2.204 MHz)
Only with these fixed settings the full bandwidth can be accessed (see also block diagram).