In a radio receiver according to the present invention, an N:1 multiplexer multiplexes N signals received through N receiver antennas into one output, and a downconverter downconverts the combined signals into baseband signals, and two 1:N analog demultiplexers demultiplex the N combined and downconverted received signals into in-phase signal elements of N received signals and quadrature-phase signal elements of N received signals.