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The knowledge of frequency and temperature dependent dielectric properties of tissue is essential to develop ultra-wideband diagnostic technologies, such as a non-invasive temperature monitoring system during hyperthermia treatment. To this end, we characterized the dielectric properties of animal liver, muscle, fat and blood in the microwave frequency range from 0.5 GHz to 7 GHz and in the temperature range between 30 °C and 50 °C. The measured data were modeled to a two-pole Cole-Cole model and a second-order polynomial was introduced to fit the Cole-Cole parameters as a function of temperature. The parametric model provides access to the dielectric properties of tissue at any frequency and temperature in the specified range.

In this work, a prototype of a laboratory microwave imaging system suitable to methodically test the ability to image, detect, and classify human brain strokes using microwave technology is presented. It consists of an antenna array holder equipped with ten newly developed slot bowtie antennas, a 2.5 D reconfigurable and replaceable human head phantom, stroke phantoms, and related measuring technology and software. This prototype was designed to allow measurement of a complete S-matrix of the antenna array. The reconfigurable and replaceable phantom has currently 23 different predefined positions for stroke phantom placement. This setting allows repeated measurements for the stroke phantoms of different types, sizes/shapes, and at different positions. It is therefore suitable for large-scale measurements with high variability of measured data for stroke detection and classification based on machine learning methods. In order to verify the functionality of the measuring system, S-parameters were measured for a hemorrhagic phantom sequentially placed on 23 different positions and distributions of dielectric parameters were reconstructed using the Gauss-Newton iterative reconstruction algorithm. The results correlate well with the actual position of the stroke phantom and its type.

In this paper, two methods for characterizing fog attenuation in terms of atmospheric visibility V in free space optics (FSO) communications are analyzed and compared. Both methods measure the fog attenuation based on V using a charge-coupled device (CCD) camera and a laser-diode at 0.55 μm. The methods are evaluated in a laboratory controlled FSO atmospheric chamber operating at individual wavelengths of 0.83, 1.31 and 1.55 μm and using a continuous optical spectrum range of 0.6 to 1.6 μm. The CCD technique shows great accuracy for V < 50 m and the laser technique for the range beyond 100 m, thus allowing enhancement of the characterization of FSO links in thick and dense fog conditions. The experimental results also indicate a wavelength dependency for V below 0.5 km where the attenuation decreases from 52 dB/km at visible wavelengths to 46 dB/km at near infrared (NIR) wavelengths.

Abstract-Objective:In this paper we present a study of a novel method to noninvasively monitor temperature during thermotherapy for instance in cancer treatment using M-sequence radar technology. The main objective is to investigate the temperature dependence of reflectivity in UWB radar signal in gelatine phantoms using electrically small antennas. Methods: The phantom was locally heated up, and consequently changes of signal reflectivity were observed. Results: An approximate linear relationship between temperature change and reflectivity variations was formulated. To show the potential of this approach we used an M-sequence MIMO radar system. The system was tested on breast-shape phantom with local heating by circulating water of controlled temperature. Delay and Sum algorithm was implemented for two-dimensional imaging. Significance: The article is a study of temperature measurement using UWB radar system for possible usage in thermotherapy.