Millimeterwave Radar Systems for In-Line Thickness Monitoring in Pipe Extrusion Production Lines

This letter presents algorithms and considerations for the applicability of millimeter wave radar systems as monitoring sensors in the field of plastic pipe extrusion. Since a constant wall thickness of the pipe is a major quality factor of the product, monitoring systems that in-line measure the thickness during the extrusion process are commonly used. Modern ultrawideband radar systems achieve target resolutions in the range of millimeters, allowing competition with well-established methods, such as ultrasound sensors, and even expensive photonic Terahertz devices. The authors describe a novel accurate and efficient method to measure the pipe-wall's thickness based on frequency domain evaluation of the material reflection. The general feasibility of W-band radar sensors, as well as the accuracy of the proposed method, is demonstrated by measurements using a moderate size polyvinyl chloride pipe.