Study on the Across Interferer of Novel Six-Port Demodulator

A novel six-port demodulator composed of the Wilkinson power dividers/combiners and the 90deg phase shifters was developed in this paper. The influence of the errors of the 90deg phase shifters on the baseband signals of the demodulator was considered and the corresponding mathematic formulas were given. The results showed that the present six-port demodulator can demodulate all orthogonal modulation signals at the center frequency. A simple baseband signal processing method was suggested to decrease the I/Q across interferer of the output baseband signals in the case of the operating frequency being departed from the center frequency. The simulation results showed that the BER performances of the demodulator were degraded less within one octave band by this method. The present work is expected to be useful for the design of the advanced demodulator with high frequency and ultra-wideband.