PURPOSE: To estimate the amount of delay distortion in a fading generation period, to improve symmetry, and to evaluate equivalent characteristics accurately, by providing a delay equalizer to one of two paths for distributing an input signal.

CONSTITUTION: An input signal from an input terminal 1 is distributed into two by a distributor 2 to the path composed of a delay line 3 and the path of a variable phase shifter 4, a variable attenuator 5, a delay equalizer 9, and a delay line 6; and the outputs of both the paths are synthesized by a synthesizer 7, whose output is outputted from an output terminal 8. This delay equalizer 9 is provided on the output side of the variable attenuator 5 to equalize delay distortion generated on a reflecting path, and the attenuation amount of frequency characteristics is made symmetrical on a prescribed frequency, thus evaluating equivalent characteristics accurately.