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. Jupiter was used for 22GHz and 43GHz, and Venus was used for the other higher frequencies.

Site Band (GHz) HPBW (arcsec) Aperture Efficiency (%) Beam Efficiency (%)
KVN-YS 22L 127 55 45
22R 126 57 46
43L 63 63 48
43R 63 64 48
86L 32 53 41
86R 32 52 41
129L 24 40 40
129R 24 40 40
KVN-US 22L 124 63 49
22R 124 64 50
43L 63 61 46
43R 63 62 47
86L 33 48 40
86R 33 45 37
129L 23 33 30
129R 23 33 30
KVN-TN 22L 126 60 48
22R 126 61 49
43L 63 63 48
43R 63 65 49
86L 32 50 39
86R 32 49 38
129L 23 33 30
129R -- -- --

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 JAN 2015 - now
    - KVN-US : from JAN 2015 - now
    - KVN-TN : from JAN 2015 - now


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Korean VLBI Network (KVN)