Chapter 2 presents the first quasi-simultaneous multi-frequency (2.3, 5.0, 8.4 and 15.4GHz) VLBI observations of the Compact Steep Spectrum (CSS) source 3C 138, and the fast-switching phase-reference observation was used only at 15.4GHz.

• 第二章研究致密陡谱源3C 138 的第一次多频(2.；3、5