A microwave position sensor with submillimeter accuracy

Calibration of a Six-Port Position Sensor via Support Vector Regression

“…Several studies on the position sensor using the six-port technique have been reported [6][7][8][9]. In these papers, the researchers mainly used the frequency modulation continuous wave (FMCW) [6][7][8] or two adequately spaced continuous wave (CW) frequencies [9] to measure the position. The advantages of a position sensor based on the six-port technique are as follows: operation in millimeter wave frequencies, no mixer, lowpower consumption, implementation in MMIC (low-cost and compact size), etc.…”

“…The researchers then found that the six-port technique could be used for communication transceivers [2][3][4], direction finding receivers [5] and ranging receivers [6][7][8][9], etc.…”

A Heterodyne Six-Port FMCW Radar Sensor Architecture Based on Beat Signal Phase Slope Techniques

“…For data acquisition time covering less than one cycle of the beat signal for beat frequency measuring, the phase slope method can be useful. This method was used for range and speed measurement in FMCW radar in [1,2] and for Doppler frequency measurement in [3][4][5][6]. The implementation of the phase slope method requires an interferometer which can be seen in millimeter-wave domain as an I/Q-mixer.…”

“…In fact DC offset, amplitude and phase imbalance and FM-AM conversion noise cause unacceptable measuring errors. To overcome the problem related to the DC offset, amplitude and phase imbalance, six-port calibration is performed conventionally, in the frequency domain with network analyzer and important data processing means are necessary in final determination of speed and range [4] and [5]. In order to avoid this complicated calibration with network analyzer, baseband data processing techniques, known as baseband analytical calibration were proposed in [1] and [2].…”

“…The implementation of the phase slope method requires an interferometer which can be seen in millimeter-wave domain as an I/Q-mixer. For cost efficiency and compactness six-port interferometers or six-port I/Qmixer have been used [1][2][3][4][5][6] in the homodyne architecture in radar sensor receivers. Although homodyne FM-CW radar is known for its simplicity, it incorporates several problems: DC offset, amplitude and phase imbalance, FM-AM conversion noise.…”