Microwave nondestructive testing of composite materials using a free space technique / Suhardi Mohamad Ali Yakop

The main objective of this project is to develop a microwave free-space measurement system in the frequency range of 8.0 to 12.5 GHz (X-Band) to measure reflection and transmission coefficients , Sn and S2i of planar samples such as Polyvinyl-Chloride (PVC), Polypropylene (PP), Nylon, Polyethylene (PE), Polyurethane and Teflon. The complex electric permittivity (s *) and complex magnetic permeability (^i*) are calculated from the measured values Sn and S2] by using a C++ language program. The measurement system consist of transmit and receive horn lens antennas, Wiltron Vector Network Analyzer, mode transitions and a printer. Diffraction effects at the edges of the samples are minimized by using spot-focusing lens antennas. Error due to multiple reflections between antennas via the surface of the sample are corrected by using a free-space LRL (Line, Reflect, Line) calibration technique.