@misc{oai:ir.soken.ac.jp:00000364,
 author = {朝木, 義晴 and アサキ, ヨシハル and ASAKI, Yoshiharu},
 month = {2016-02-17, 2016-02-17},
 note = {Compensation of interferometer phase fluctuations due mainly to the atmospheruc water vapor is one of the most important subjects for future millimeter- and submillimeter-wave radio synthesis arrays and future millimeter-wave very long baseline arrays because the fluctuations are the most serious limiting factor for their spatial resolutions and sensitivities.
   In the present thesis, a method for the atmospheric phase cornpensatxon called 'Paired Antennas Method (PAM)' is examined in detail.  The PAM uses pairs of closely located antennas in order to simultaneously observe a target radio source and an adjacent reference calibrator with nearly parallel baselines and correct the interferometer phase of the target source using that of the reference source.
  The effectiveness of the PAM was studied by means of interferometer phase compensation experiments using the Nobeyama Millimeter Array and the Nobeyarna Radio Seeing Monitor at Nobeyuma Radio Observatory of National Astrononucal Observatory, Japan.  In the experiments, a celestial radio source 3C 279 and a geostationary satellite (Japanese Communication Satellite called 'CS') were simultaneously observed and the angular-separation dependence of the effectiveness of the phase compensation was investigated.
  It was always clearly seen in the experiments that the phase compensation with the PAM was very successful when the separation angle was smaller than a few degrees, even in the case that the millimeter-wave interferometer phase of the target source was compensated using the centimeter-wave phase of the reference source.  The degree of phase compensation aheady achieved the level of less than 0.1 mm rms in excess path length, which is the goal of the planned new arrays for the future submillimeter-wave radio interferometry, when the atmospheric condition at Nobeyama was good enough.  This demonstrates that the high resolution and high quality radio images are readily obtainable in the future large submillimeter-wave arrays at least if one uses the PAM or similar method of equivalent performance in order to eliminate the atmospheric phase fluctuations.
  A model of the atmospheric structure was constructed to account for the experimental results on the basis of the Kolmogorov turbulence, frozen flow, and phase screen.  A statistical calculation of the residual rms phase of the corrected phase in the PAM, based on the above atmospheric structure model, led to the numerical results in excellent agreement with a number of features of the experimental results.  This implies that the underlying model, though simple, is a fairly good approximation of the reality.  The computer simulations for the phase compensation in terms of the PAM at the potential sites of the future submillimeter-wave arrays revealed impressive results promising that the necessary level of the phase compensation for the future arrays is achieved, provided that suitable reference sources are available within a few degrees around a target source.
  The antenna-switching method is also a promising phase compensation technique similar to the PAM.  Although the switching observation itself was not carried out in the phase compensation experiments with the Nobeyama Millimeter Array and Nobeyama Radio Seeing Monitor, I studied this method using the demonstrated data series produced from the PAM-experimental data and investigated the separation-angle dependence.  Using the statistical model developed in the present thesis, the feasibility of the antenna-switching method was compared with that of the PAM and investigated in terms of the specific parameters such as the switching cycle time or the ON source time to a target source within one switching cycle.  The computer simulations based on the model showed the potential of the antenna-switching method, which is equally effective in the phase compensation ability as the PAM if radio telescope antennas are able to slew fast enough.  It was thus confirmed that the fast antenna-switching method is an effective way to realize the precise phase compensation with the simpler system than the PAM's.  It is also noted that the PAM has an important merit in the long time integration to obtain the higher signal-to-noise ratio while observing weak radio sources., application/pdf, 総研大甲第262号},
 title = {Compensation of Atmospheric Phase Fluctuations in Radio Interferometry},
 year = {}
}