KVN and VERA Array

Brief Summary of KVN Antennas

The KVN antennas are also designed to be a shaped-Cassegrain-type antenna with an AZ-EL mount. The telescope has a 21 m diameter main reflector with a focal length of 6.78 m. The main reflector consists of 200 aluminum panels with a manufacturing surface accuracy of about 65 $\mu$m. The slewing speed of the main reflector is 3 $^{\circ}$/sec, which enables fast position-switching observations (Table [*]). The sub-reflector position, tilt, and tip are remotely controlled and modeled to compensate for the gravitational deformation of the main reflector and for the sagging-down of the sub-reflector itself.


Table: Driving performance of KaVA antennas.
Driving axis Driving range Max. driving speed Max. driving acceleration
VERA
AZ$^a$ $-$90$^{\circ}\sim$450$^{\circ}$ 2.1$^{\circ}$/sec 2.1$^{\circ}$/sec$^2$
EL 5$^{\circ}\sim$85$^{\circ}$ 2.1$^{\circ}$/sec 2.1$^{\circ}$/sec$^2$
FR$^b$ $-$270$^{\circ}\sim$270$^{\circ}$ 3.1$^{\circ}$/sec 3.1$^{\circ}$/sec$^2$
KVN
AZ$^a$ $-$90$^{\circ}\sim$450$^{\circ}$ 3$^{\circ}$/sec 3$^{\circ}$/sec$^2$
EL 5$^{\circ}\sim$85$^{\circ}$ 3$^{\circ}$/sec 3$^{\circ}$/sec$^2$
$^a$The north is 0$^{\circ}$ and the east is 90$^{\circ}$.
$^b$FR is 0$^{\circ}$ when Beam-1 is at the sky side and Beam-2 is at the ground side,
 and CW is positive when an antenna is seen from a target source.


Table: Aperture efficiency and beam size of KaVA antennas.
K band (22 GHz) Q band (43 GHz)
$\eta_{\rm A}$ HPBW $\eta_{\rm A}$ HPBW
Antenna Name (%) (arcsec) (%) (arcsec)
Mizusawa 47 141 51 71
Iriki 47 149 44 78
Ogasawara 50 143 45 78
Ishigakijima 49 144 48 79
Yonsei 55 127 63 63
Ulsan 63 124 61 63
Tamna 60 126 63 63



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KaVA ( KVN and VERA Array )