The combiner 1 has a resin base 11 and a reflecting and polarizing member 12. Selecting the cuff to be wide enough to define limb occlusion pressure at or below the systolic blood pressure assures that this maneuver does not compromise cessation of blood flow to the limb. The I and Q signals are equalized, and the equalized I and Q signals are digitized. In another aspect, the apparatus includes a gravure sleeve and a heatable mandrel disposed inside the gravure sleeve.