Near-Field Power Density Mapping of Close-to-Body Low-Power Mmwave Devices

• Published in: IEEE antennas and wireless propagation letters 2023-10, Vol.22 (10), p.1-5
• Main Authors: Ziane, Massinissa, Boriskin, Artem, Zhadobov, Maxim
• Format: Article
• Language: English
• Subjects: Absorbed power density (APD); Antenna measurements; Conduction heating; Conductive heat transfer; dosimetry; Engineering Sciences; Heating systems; Horn antennas; Infrared cameras; Millimeter wave communication; Millimeter waves; millimeter-wave (mmWave) measurements; Noise measurement; Parasitic elements (antennas); Phantoms; Power management; Power measurement; Signal to noise ratio; Temperature measurement
• ISSN: 1536-1225; 1548-5757
• DOI: 10.1109/LAWP.2023.3286944

This letter introduces a method for power density (PD) measurement of low-power millimeter-wave devices, accounting for antenna/body coupling. This technique employs a thin solid absorbing structure with equivalent scattering properties used to convert the absorbed power into a heat pattern measured by an infrared (IR) camera. The measured IR pattern is then used to reconstruct the PD distribution. The lock-in technique is used to enhance the signal-to-noise ratio. It consists in filtering the ambient IR noise as well as removing the parasitic heat conduction effect. The reduction of noise enables achieving a measurement sensitivity of the order of 1 mW/cm^{2}, substantially overcoming the sensitivity without lock-in (> 10 dB). The proposed approach is experimentally validated for a conical horn antenna at 60 GHz. For the first time, this study demonstrates the sensitivity of IR-based measurements sufficient enough to assess the compliance of medium- and low-power wireless devices above 6 GHz.