Analysis Design and Characterization of Small Gap Photoconductive Dipole Antenna for Terahertz Imaging Applications

Abstract

The terahertz (THz) regime of the electromagnetic spectrum is rich because of its unique properties with the emerging possibilities in various applications such as wireless communications, imaging, non-destructive testing, security scanning and process control. The unique features of THz waves are non-ionizing radiation, better resolution than the microwave, unique spectral absorption, and an ability to propagate through dielectric materials. The spectroscopy with high spectral resolution at frequencies in THz range is an influential analytical tool for investigating the structure as well as the energy levels of molecules and atoms. Using THz spectroscopy, it is potentially possible to detect explosive and illicit drugs even though they are obscured because THz radiations can rapidly transmit through materials such as plastics, paper products, luggage, clothing and other non-conductive materials. Moreover, on comparing the measured reflectivity of the THz spectra with known calibration spectra, it is easier to identify the presence of these agents and distinguish them from benign objects. newlineFor the imaging applications, the continuous wave (narrowband) or pulsed wave (broadband) THz systems for the generation of THz radiation is used and this classification is based on the laser source used to generate photocurrent. Moreover, the applications such as homeland security, defence as well as safety of aviation industry have placed huge demands on the growth of advanced imaging systems. However, the visible and the infrared imagery is providing high image quality, but they are mired by atmospheric obscurants such as cloud cover, dust storms, sand, smoke, fog and rain. Therefore, the THz imaging provides an attractive means to diminish or eliminate the impact of low visibility conditions due to such atmospheric conditions. Further, in close-range sensing and imaging applications, the pulsed THz sources are more favourable for acquiring depth information.