PURPOSE: To compensate for phase vibration in a transmission pulse by causing a phase vibration in a pulse opposite in the characteristic to a transmission type signal.

CONSTITUTION: The characteristic of a phase variation in a transmission pulse depending on characteristics of a power amplifier as shown in the drawing (a) is measured and displayed on an oscilloscope, an X-Y recorder or the like. Based on such a data, a phase vibration value is sampled manually for a unit time allowing a phase shifter for compensation to respond to rewriting corresponding to a set phase shift level to determine a phase difference between this and the latter half of a pulse free from phase variations. The phase difference is a necessary correction value corresponding to sampling times. This correction value is quantized by the quantization unit of the compensation phase shifter, inverted in the symbol and applied to the phase shifter corresponding to the sampling times. With such an arrangement, as shown in the drawing (b), a transmission type signal has a phase variation opposite in the characteristic to the phase variation characteristic of the drawing (a) and thus, the relative phase of a transmission pulse emitted from an array antenna with respect to a coherent signal gives a phase waveform with limited variation as shown in the drawing (c).