In the Quadrature Phase Shift Keying (QPSK) front-end communication receiver system, a six-port device is the key component for identifying the microwave reflection coefficient of the receiving QPSK signal. The use of a mixer in a conventional QPSK receiver can be avoided by employing a six-port device in the front end communication receiver. However, the traditional six-port receiver performance is usually poor due to limited operational bandwidth from high amplitude imbalance and high phase imbalance of its transmission coefficients. Therefore, in this study, a six-port device is optimized for achieving low amplitude and phase imbalance that lead to wideband characteristics of QPSK demodulation in the front-end communication receiver. Since a six-port device is constituted by a power divider and 3-dB quadrature couplers, the optimization starts by designing both components individually using simulation tools, CST Microwave Studio. The optimization of the power divider is done by employing multi-section techniques on a Wilkinson power divider while rectangular stubs are introduced in a 3-dB quadrature elliptical coupler. By considering the overall Sparameter performances for return loss and isolation to be more than 10 dB and transmission coefficients to be -3 ± 0.5 dB, the power divider results show that the measured double-stage performs better in a fractional bandwidth of 168.62% across a frequency range 1 – 11.75 GHz compared to a single-stage which only has a percentage of 139.80% within a frequency range of 1.55 – 8.75 GHz. To compare the stubs in the coupler, the results show that good performance is achieved over the entire bandwidth of 3.44 – 8.03 GHz for return loss and isolation of more than 10 dB, transmission coefficients of -3 ± 1.5 dB and a phase difference across Ports 2 and 3 with respect to Port 1 of 90' ± 5'.
