Korean VLBI Network (KVN)

Antenna Beam Size & Aperture Efficiency

Following table shows measurements of main-beam size, aperture efficiency and main-beam effciency at 22.235, 43.122, 86.243 and 129.363GHz bewteen 2013 September and 2014 January. Jupiter was used for 22GHz and 43GHz, and Mars was used for the other higher frequencies.

Site Band (GHz) HPBW (arcsec) Aperture Efficiency (%) Beam Efficiency (%)
KVN-YS 22L 127 56 46
22R 126 59 47
43L 63 64 48
43R 63 65 49
86L 32 49 38
86R 32 49 38
129L 23 35 33
129R 23 37 35
KVN-US 22L 124 61 47
22R 124 63 49
43L 63 62 47
43R 63 64 48
86L 33 45 36
129L 23 33 30
KVN-TN 22L 125 58 46
22R 125 59 47
43L 61 60 43
43R 61 65 46
86L 32 48 37
86R 32 47 37
129L 22 33 27
129R 22 33 27

1. Elevation dependency

Aperture efficiency varies with elevation. The elevation dependency of KVN antannas represented as gain curve is described in next section. Those in the above table are the maximum values.

2. Frequency dependency of beam efficiency

Beam efficiency varies with beam size. The measured HPBWs are tabulated in the above table, which are almost the same as the theoretical ones(= wavelength / diameter of antenna). In order to get a beam efficiency at 90 GHz, you have to multiply (86/90)2 to that at 86 GHz.

3. Quantization correction of single-dish spectrum data

In case you are reducing single-dish spectrum data, you need to multifly a factor of 1.25 before applying efficiency corrections. This is to compensate for the effect of the digital filter and spectrometer.

The above table can be applied for the following observing season.
    - KVN-YS : from AUG 2013 - now
    - KVN-US : from AUG 2013 - now
    - KVN-TN : from AUG 2013 - now


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Korean VLBI Network (KVN)