Adjacent channel suppression (ACS) in direct-digital six-port receivers

System simulation results of a digital six-port receiver operating with an ideal six-port (120 degrees between Q(1) points), over two adjacent channel s, are compared with a second six-port receiver operating with a special si x-port circuit possessing 120 degrees separation between Q(i) points in the receiving channel and 0 degrees separation between Q(i) points in the adja cent channel. Theoretical analysis and simulation results are given on adja cent channel suppression using 64-QAM modulation. The implementation of spe cial six-port A CS requires a six-port wave structure with constant phase v elocity in the receiving channel and reduced phase velocity in the adjacent channel to decrease the angles of the two adjacent Q(1) points of the six- port by 120 degrees. (C) 2001 John Wiley & Sons, Inc.