Radar system for the study of tree trunks

• Main Author: Ng, Ronald Tze Hao
• Other Authors: Lee Yee Hui
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2020
• Subjects: Engineering::Electrical and electronic engineering::Antennas, wave guides, microwaves, radar, radio
• Online Access: https://hdl.handle.net/10356/140590
• Institution: Nanyang Technological University

With the occurrence of fallen trees causing public safety concerns in Singapore, there has been an additional emphasis on tree inspection in recent years. There are several methods of tree inspection such as sonic tomography and resistography but ground penetrating radars are generally the preferred method of testing due to its non-destructive and non-invasive nature. As such, the main objective of this project is to assemble a radar system for efficient and effective tree trunk inspections. The work done in this project can be classified into three distinct phases – Learning phase, Experimental phase, and Functional phase. For the initial stages of this project, a simple radar system, consisting of a vector network analyser and a pair of antennas, was assembled, and subsequently used to conduct several fundamental tests to understand the system capabilities. As the concept of subsurface scanning is similar to the process of detecting abnormalities within tree trunks, the second phase mostly involved soil scans on a testbed to determine the system’s ability to detect buried object beneath surfaces. By conducting similar tests with different antenna placement methods, it was concluded that the system’s detection performance improved when the antennas were placed parallel to each other. It was also discovered that noise interference at the receiver can be reduced by lowering the intermediate frequency bandwidth of the system. In the final phase, there were several modifications done to the radar system and testbed. Firstly, newly developed antennas were used for the transmission and receiving of signal waveforms. The soil of the testbed was also replaced with the correct Approved Soil Mix. With the new antennas and soil, more soil scans were conducted to detect buried objects. From the results obtained, there were positive signs that indicated that the location of the buried objects, which was a promising discovery for this project.