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.

Antenna Beam Size & Aperture Efficiency
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 53 41
129L 23 43 39
129R 23 43 39
KVN-US 22L 124 63 49
22R 124 64 50
43L 63 61 46
43R 63 62 47
86L 32 57 44
86R 32 57 44
129L 23 40 36
129R 23 40 36
KVN-TN 22L 126 60 48
22R 126 61 49
43L 63 63 48
43R 63 65 49
86L 32 57 44
86R 32 57 44
129L 23 40 36
129R 23 40 36

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 Nov 2016 - now
    - KVN-US : from Feb 2016 - now
    - KVN-TN : from Nov 2016 - now


KASI logo image

Korean VLBI Network (KVN)