The well-known six-port technology has found widespread applications in the measurements of microwave networks .Recently new applications were also suggested to use six-port junctions and six-port calibration techniques in communication receivers. In the existing six-port technology, the tested signal is mixed and compared with a standard carrier wave without modulation to extract its phase and amplitude information. In this paper, we use a modulated wave instead of the carrier to realize a RF comparator. In this case the output data of the six-port gives us the amplitude ratio and phase difference of the two input signals. Simulations using SPW (Signal Processing Workstation) software are performed to validate the proposed comparator. When two identical 64 QAM signals with different amplitude and phase are fed into the six-port comparator, the output takes a constant value related to the ratio of the input amplitudes and phase difference. If two different signals are used as the input, the output of the six-port will change with time. These changes may be used to equalize the input signals, to eliminate the distortion of one of the incoming signal by comparison it with the standard one, to identify signatures and so forth.