2021 PhotonIcs & Electromagnetics Research Symposium (PIERS), Hangzhou, China, 22 November Microwave Imaging for Lung Covid-19 Infection Detection through Huygens Principle B. Khalesi 1, 2, 3 , B. Khalid 1 , N. Ghavami 2, 3 , S. Dudley 1 , M. Ghavami 1 , and G. Tiberi 1, 2, 3 1 School of Engineering, London South Bank University, London, UK 2 Umbria Bioengineering Technologies, Perugia, Italy 3 UBT UK Division, London, UK Abstract— This paper aims to show the capability of the Huygens Principle-based microwave imaging for use in Lung COVID-19 infection detection. Frequency-domain measurements have been performed in an anechoic chamber using two Microstrip antennas operating at frequency range of 1 to 5 GHz, in a multi-bistatic fashion, employing dedicated phantoms that mimic the dimensions and the dielectric properties of a human torso, containing a target mimicking an infection. A Multi-layered elliptically-shaped torso-mimicking phantom having the circumference of 82 cm has been constructed; the external layer mimics the dielectric properties of a combination of muscle, fat and rib bone tissues, the inner layer mimics the dielectric properties of lung (inflated). A cylindrically-shaped tube of water has been positioned inside the inner layer to dielectrically mimic the infection. The S 21 signals have been used for image reconstruction (after removing artifacts), obtaining detection with a signal to clutter ratio of 7 dB. Our results confirm that Huygens based technique can be successfully used for lung infection detection even if antennas and phantom are in free space, i.e., no coupling liquid is required. 1. INTRODUCTION COVID-19, which emerged in late 2019, has now become a worldwide pandemic. COVID-19 lung lesions may manifest with chest CT imaging abnormalities, even in asymptomatic patients, with evolution to diffuse bilateral ground-glass opacities [1]. However, it is not recommended to use CT as a routine screening modality because it should be reserved for hospitalized and symptomatic patients. Moreover, although CT is important for the tracking of the treatment procedure of COVID-19 infection [2], the accumulation of ionizing radiation may represent a concern when using this technique for monitoring. Microwave imaging has attracted growing attention, especially for its applicability towards breast cancer detection, motivated by the significant contrast in the dielectric properties at mi- crowave frequencies (1–10GHz) between normal and malignant tissues [3]. Recently, microwave imaging has also been applied for brain stroke classification, bone imaging and lung cancer detec- tion [4, 5]. Specifically, in [4], the authors introduced a three-dimensional electromagnetic torso scanner that operates between 0.83 and 1.9 GHz. In [4] and [5] it is reported that the relative permittivity and conductivity of cancerous tissues are up to 3 times and 2 times larger than normal tissues, respectively. Since COVID-19 infection leads to ground-glass opacities in the lungs as shown in [2], such opacities imply a contrast in dielectric properties with respect to the surrounding normal tissues [6]; it follows that microwave imaging could detect such opacities, which are larger in size than lung cancers. In general, current research in microwave imaging can be divided mainly into tomography and linear scattering techniques. Among linear scattering techniques, the Huygens Principle (HP) based technique allows to detect dielectric inhomogeneities in frequency domain [7]. Specifically, using HP to forward propagate the UWB signals collected outside the investigation domain permits the capture of contrast, i.e., the extent to which different tissues, or different condition of tissues, can be discriminated in the final image. In addition, HP requires a very simple hardware set-up, i.e., one transmitting antenna and one receiving antenna, coupled through a vector network analyzer (VNA), which rotate around the object to collect the signal in a multi-bistatic fashion. Up to now, HP has been used for breast, bone, and brain imaging. The aim of this paper is to assess the capability of the proposed HP procedure in detecting Lung COVID-19 infection through measurements inside an anechoic chamber employing dedicated phantoms that mimic the dimensions and the dielectric properties of a human torso, containing a target mimicking an infection. In order to detect the Lung COVID-19 infection inside a human 2885 2021 Photonics & Electromagnetics Research Symposium (PIERS) | 978-1-7281-7247-7/21/$31.00 ©2021 IEEE | DOI: 10.1109/PIERS53385.2021.9694816 © IEEE 2021. This article is free to access and download, along with rights for full text and data mining, re-use and analysis.