Microwave nondestructive testing of timber using a free-space technique / Hamidah Limat

The concern of this project is to develop a free-space measurement system at microwave frequenties. Micro wave Nondestructive Testing (MNDT) Techniques will be used for measuring moisture content, volume density, loss tangent (tan 5) and power absorption coëfficiënt (PAC) for different type of timber ( Light Red Meranti, Yellow Meranti and Keruing). Reflection and transmission measurement s will be performed on a free-space micro wave measurement set up in frequency range of 8.0 to 12.5GHz. Free-space set-up consists of two spot-focusing hom lens (transmit and receive antennas), wave guide transistions, coaxial cabies and microwave Wiltron 372698 vector network analyzer . Errors due to difiraction effects at the edges of the specimen is minimized because of far field focussing abüity of antennas and multiple reflections bet ween antennas via the surface of specimen are eliminated by using free-space LRL (Line , Refiect and Line) calibration technique. Complex dielectric permittivity of timber will be measured to estimate moisture content of different types of timber from permittivity values . This MNDT technique is a simple , fast , nondestructive , contactless and accurate method for evaluating properties of timber.