1. A MIMO channel emulator comprising a channel emulator mixing matrix, the channel emulator mixing matrix receiving N inputs and generating M outputs, the channel emulator mixing matrix comprising: a plurality of splitters, each splitter receiving at least one of the N inputs, each splitter generating a plurality of signal paths; at least one phase shifter, each phase shifter adjustably shifting a phase of at least one signal path; and a plurality of combiners, each combiner receiving more than one of the plurality of signal paths, at least one combiner receiving a phase adjusted signal path, each combiner generating at least one of the M outputs.