Broadband Six-Port Reflectometer Insensitive to Impedance Mismatch of Power Detectors

In this paper, a new six-port reflectometer is proposed, which is capable of optimum operation over a wide frequency range from 1.2 GHz to 4.8 GHz with power detectors that exhibit poor impedance match. In the proposed concept the signals reflected from power detectors are redirected to matched loads, hence they do not impact the signal distribution scheme defining the measurement uncertainty. As a result, the six-port can operate equally well with matched and nonmatched power detectors. The six-port reflectometer is designed, fabricated, calibrated, and used to measure complex reflection coefficients over $40-\mathrm{dB}$ magnitude’s range showing very good agreement with measurements done with a commercial vector network analyzer.