Analysis and synthesis of six-port modulators

Abstract

The six-port modulation holds potential benefits for communications, radars, and imaging. In this dissertation, we have derived the transfer functions for serial and parallel six-port modulators and investigated their performances in terms of carrier leakage, Gray mapping, and conversion efficiencies based on QPSK modulation. Our analysis shows that carrier leakage is minimized when switching reflection coefficient, N ON is equal to -N OFF at selected ports. In addition, the symbol constellation shows that only the parallel six-port QPSK modulator has Gray mapping feature. Further analysis has proven that the serial and parallel modulator has a maximum 100% and 50% theoretical conversion efficiency respectively. In addition, we have proposed a novel 16QAM six-port modulator to increase the data rate. Prototypes have been designed and built to validate the performances of 16QAM and QPSK six ports modulator at 4.2GHz carrier frequency. Our theoretical and measured results show good agreements.