Millimeter-Wave Imaging with Range-Resolved 3D Depth Extraction Using Glow Discharge Detection and Frequency-Modulated Continuous Wave Radar

This paper presents a preliminary proof-of-concept study of a novel approach to 3D millimeter-wave (MMW) imaging, demonstrating the first implementation of Glow Discharge Detectors (GDDs) in this domain. GDDs offer significant advantages over conventional MMW detectors like Schottky diodes or bolometers due to their cost-effectiveness, robustness to high-power MMW signals, and reliable operation under diverse environmental conditions. Based on weakly ionized plasma (WIP) technology, GDDs detect changes in discharge current upon MMW exposure, providing an affordable and durable alternative to traditional MMW imaging systems. The system operates within a subset of the W-band (101–109 GHz), utilizing a customized transmitter (Tx 272 from VDI Technologies), which operates at a frequency range proportional to the VCO supply voltage level. The Frequency-Modulated Continuous Wave (FMCW) signal source is split into target and reference paths via a compact waveguide splitter, improving stability and reducing the complexity of the optical setup. Reflected signals are processed by the GDD, which functions as a heterodyne receiver, and Fast Fourier Transform (FFT) is used to extract range data. A 2D grid scanning mechanism, controlled by step motors, maps the surface of the object, while depth information is derived from FMCW frequency differentials to construct a complete 3D profile. This work demonstrates the potential of GDD-based 3D MMW imaging as a low-cost, efficient solution for security screening and industrial inspection. By addressing challenges in cost, scalability, and performance under high-power MMW signals, this approach represents a significant step forward in making MMW imaging technology more accessible, while highlighting the need for further development to achieve practical implementation.