A novel phase detection system structure applicable to the calibration technique essential for millimeter-wave beamforming systems is presented in this paper. We propose the phase detection system that can measure up to 360°, which overcomes the limitations of conventional phase difference measurement. The structure of the phase detection system was designed based on the theoretical
equation. A direct digital synthesis (DDS) capable of phase change and microcontroller unit (MCU) were used to measure the performance of phase detection systems. The performance of the proposed phase detection system was measured by two RF signals output from the DDS. The phase detection software was implemented using MATLAB to calculate the actual phase difference value matching the output value of the detection system. As a result of the experiment, it was confirmed that the phase difference between the two signals was measured up to 360°. Compared with the actual phase difference, the maximum phase detection error value using the phase detection system was less than 1°. The proposed phase detection system can be applied to the calibration technique
of various active phased array antenna systems in the millimeter-wave band.