Geodetic VLBI experiments are usually conducted at S/X dual bands. Some advantages can be gained at some higher frequency band and in particular at 22 GHz band (K band). We organized a geodetic VLBI experiment on the 16th of February 1991 between Kashima 34m antenna of the Communication Research Laboratory (CRL), in Japan and Medicina 32 m telescope of the Institute of antenna(IRA), in Italy. The phase calibrator was developed using a new “up-conversion” scheme for K band. Data relative to 212 observations of 40 sources were correlated and for 152 scans we obtained correlated amplitudes, delays and delay rates. The r.m.s. residuals have been found to be 100 ps for delays, and 74 fs/s for delay rates. The coherence loss of correlation amplitude becomes large at higher frequency band than 22GHz due to the atmospheric scintillation. The estimated method of the coherence loss was presented. The correlated flux densities at K band evaluated from them were found to be smaller than the ones at X band in general.
ALMA High-frequency Long-baseline Campaign in 2017: A Comparison of the Band-to-band and In-band Phase Calibration Techniques and Phase-calibrator Separation Angles