Adaptive Arrays Can Be Used to Separate Communication Signals

Using eigentheory, it is shown how up to n unknown independent narrowband signals arriving from different directions at an array of n antenna elements can be separated into n channels where each channel contains primarily one signal. An expression for the signal-to-interference ratio (SIR) on eachoutput channel is determined analytically and evaluated for many illustrative cases. The results show that in most cases the SIR is + 10 dB or greater; only when two signals arrive within a few degrees of each other does the SIR fall substantially below 0 dB.