Measurement of Emissivity of the ALMA Antenna Panel at 840 GHz Using NbN-Based Heterodyne SIS Receiver
نویسندگان
چکیده
We measured emissivity of sample presenting panel of ALMA antenna using Band-10 heterodyne SIS receiver as antenna switching balanced radiometer with 8 GHz instantaneous bandwidth. Receiver noise temperature measured with 80 K/300 K antenna loads was ≈560 K (DSB). Emissivity of the surface is detected at LO frequency about 840 GHz via the imbalance of the antenna switch due to extra reflection from sample of panel; absorption 0.25±0.10 % is calculated from measured emissivity. To confirm measured value, samples made of phosphor bronze and stainless steel are tested using the same technique. The values of 0.30±0.10 % and 1.10±0.10 % are obtained for these samples correspondingly that is consistent with previous data obtained using direct detector radiometers.
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