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 | 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
Korean VLBI Network (KVN)