System Temperature Characterization of Nkutunse Receiver at 5GHz (Continuum) and 6.7GHz (Methanol Maser)

摘要

This paper presents the characterization of system temperature (Tsys) for the first stage receiver of the 32 m diameter cassegrain antenna at Nkutunse (Ghana) with a hot load jig. The hot load jig was place above the Beam Wave Guide and the Feed horn and the noise diode switched ON and OFF. The recorded Tsys values at 5 GHz (Continuum) was 160 K and at 6.7 GHz (Methanol Maser) was 120 K. These high Tsys values, is as a result of using one LNA in the first stage. The conducted measurement considered both right hand cross polarization (RHCP) and left hand cross polarization (LHCP) of the signal chain. With cascaded LNAs in the final stage of the receiver, it is certain the required 75 K for the telescope operation can be achieved. However, a second approach to keep the Tsys in check means that Radio Frequency Interference (RFI) at the site should be mitigated, since it adds to the cumulative noise power of a system and thereby reducing the sensitivity of the receiver.