In recent years, the presence of short-range
millimeter-wave radar in civil application has increased significantly.
Autonomous driving, security, 3D imaging and high data rate
communication systems are a few examples. The next challenge is
the integration inside small form-factor devices, such as smartphones
(e.g. gesture recognition). The main challenge is implementation of
a truly low-power, low-complexity high-resolution radar. The most
popular approach is the Frequency Modulated Continuous Wave
(FMCW) radar, with an analog multiplication front-end. In this
paper, we present an approach for adaptive estimation and correction
of impairments of such front-end, specifically implemented using
the Six-Port Device (SPD) as the multiplier element. The proposed
algorithm was simulated and implemented on a 60 GHz radar lab
 T. Saito, N. Okubo, Y. Kawasaki, O. Isaji, and H. Suzuki,
“An fm-cw radar module with front-end switching heterodyne
receiver,” in 1992 IEEE MTT-S Microwave Symposium
Digest, June 1992, pp. 713–716 vol.2.
 G. F. Engen, “The six-port reflectometer: An alternative
network analyzer,” IEEE Transactions on Microwave Theory
and Techniques, vol. 25, no. 12, pp. 1075–1080, Dec
 E. Moldovan, S. O. Tatu, T. Gaman, K. Wu, and R. G.
Bosisio, “A new 94-ghz six-port collision-avoidance radar
sensor,” IEEE Transactions on Microwave Theory and
Techniques, vol. 52, no. 3, pp. 751–759, March 2004.
 A. Stelzer, C. G. Diskus, K. Lubke, and H. W. Thim, “A
microwave position sensor with submillimeter accuracy,”
IEEE Transactions on Microwave Theory and Techniques,
vol. 47, no. 12, pp. 2621–2624, Dec 1999.
 A. Koelpin, G. Vinci, F. Barbon, S. Lindner, G. Fischer,
and R. Weigel, “The six-port technology: A low-cost concept
for precise position measurements,” in International
Multi-Conference on Systems, Sygnals Devices, March
2012, pp. 1–5.