Nihon University

Takuya Eguchi

Masayoshi Tanaka

N (integer equal to or above 3) quaternary phase shift keying (QPSK) outputs having different amplitude levels, i.e., r2=r1&#xd7;2, i=2 . . . N with respect to a maximum amplitude level r1 are superposed after power amplification to form M(=2)-valued/quadrature amplitude modulation (QAM), and N-1 outputs si except the quaternary phase shift keying QPSK-having the maximum amplitude r1 are subjected to power amplification in this formation, then the outputs are combined by a directional coupler to obtain a combined signal, and an output of the quaternary phase shift keying QPSK-and the combined signal are transmitted from two systems of antennas to be vectorially superposed and combined in a space.

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Tokyo, Japan

Takuya Eguchi