Design of millimeter-wave probe for diagnosis of human skin

Millimeter-wave reflectometry is a potentially interesting method to measure varying properties of human-skin tissue. With this method, an open-ended waveguide probe is used, which is pressed against the skin (or bandage), to measure the reflection coefficient in the millimeter-wave frequency band of 40-60 GHz. Thanks to todays low-cost millimeter-wave silicon-based chip technology, this method could possibly be made available for massive usage in home-care situations. However, the measurement conditions in such situations might be ill-defined in the sense that parameters such as probe pressure and probeskin angle are not well controlled. In this paper, two candidate probe types are investigated as regards the sensitivity for probe pressure on the skin, probe-skin angle and layers of bandage between probe and skin. The probes considered are either with or without flange. The unflanged probe turns out to be the most promising candidate provided that careful calibration is possible despite the missing flange.