A THz Near-Field Scanning System

Abstract

Recent improvement in different technologies have led the previously terahertz frequency band available for imaging, and sensing systems. The 'terahertz gap' has a frequency ranges between ~300 GHz and ~10 THz in the electromagnetic spectrum, which inside the gap of microwave, and infrared. As the terahertz radiation are non-ionizing, it motivates many researchers that race to realize the terahertz system for imaging, and sensing applications. The aims of this project are building a near-field planar scanning platform for imaging, and antenna radiation pattern measurement at such terahertz frequency range. The integration of hardware, and software techniques help make an automatic measurement system by controlling a three-axis step motor with a full-step resolution of 2.5 μm, and 1/8 step resolution of 0.31 μm. After taking the measurement of the antenna under test with the network analyzer, and extenders, the software would further compute the antenna directivity, and radiation pattern based on the measured scattering parameters, and display the desired antenna characteristics. The effect of the measuring probe will be delineated by means of probe compensation techniques. The simulation, and measurement result of a horn antenna for testing the method will be presented in the report.