Boris Litvak

Microwave sensor for accurate measurements of water solution concentrations

The paper presents results of sensitivity estimations of the microwave sensor designed for controlling concentration of various mixture solutions. It consists of the resonator supporting TM010 mode with the axial glass tube filled with the solution under test. Concentrations of both organic (sugar, alcohol) and inorganic (NaCl, KMnO4 ) water solutions were determined with high accuracy. The sensitivity of the sensor in determination of NaCl is 0.4 dB/(mg/ml) within the concentration range 0 - 1 %. It is about the two orders higher than sensitivity of the sensor based on near field dielectric resonator.

Optimized Microwave Sensor for Online Concentration Measurements of Binary Liquid Mixtures

This paper describes microwave sensors designed for online measurements concentration of binary liquid mixtures. It is based on the cylindrical resonator having axial glass tube filled with the liquid under test. The input coupling element has been optimized using 3D EM simulator (CST Microwave Studio) in order to reach maximum sensitivity and concentration resolution. The sensor can be calibrated for a variety of organic and inorganic binary mixtures. Examples of operation of the sensor with mixtures such as water-methanol, magnesium-sulphate, and water-sodium chloride-glucose are reported.

Non-Imaging MM-Wave FMCW Sensor for Pedestrian Detection

This paper describes a millimeter-wave sensor that is able to detect pedestrians, thereby reducing the likelihood of human road injuries or fatalities. The sensor consists of a transmit/receive channel module, operating in the millimeter-wave range (W-band) using frequency-modulated-continuous-wave mode. The laboratory prototypes of the sensor have been designed and tested in real-life environment. An analysis of system performance and experiments conducted has indicated a high-resolution, detection ability of both adults and children at a distance of up to 100-150 m.

Linear FM radar operating in the Tera-Hertz regime for concealed objects detection

Sub-millimeter and Terahertz waves maintain reasonable penetration depth in certain common materials, such as cloth, plastic, wood, sand and soil. Therefore, THz radiation can detect concealed weapons since many non-metallic, non-polar materials are transparent to this type of radiation (and are not transparent to visible radiation). Target compounds such as explosives and illicit drugs have characteristic THz spectra that can be used to identify these compounds. Investigation, design and development of a sub-millimeter wave remote sensing RADAR system for homeland security applications are presented. The RADAR, operating at 330GHz is based on transmission of a frequency modulated continuous wave (FMCW) and aimed at detection of concealed objects for ranges up to 20m. The system consists of 2 horn-lens antennas integrated with a homodyne transceiver. The synthesized linear FM signal with a frequency span of 200MHz at X-band is multiplied by a factor of 32 to generate the transmitted Tera-Hertz wave. Using a splitter, the signal is fed to an antenna and to a local oscillator port of a second harmonic balanced mixer. As a result, an intermediate frequency signal is obtained, containing the information on the target. Distance measurements were made by performing data acquisition and signal processing commercial programs, resulting in a range resolution better than 1cm. Preliminary Tera-Hertz imaging was also carried out to perform a three-dimensional image of the object.

Portable Passive Millimeter-Wave Sensor for Detecting Concealed Weapons and Explosives Hidden on a Human Body

This paper describes a portable passive millimeter-wave sensor designed for remote detection of both metallic and non-metallic objects hidden on a human body under cloth. The sensor is based on a directly detection and analyses of the energy emitted by a human body. The algorithm of detection estimates unimodality features of traces recorded in the process of a manual scan. The sensor demonstrates a detection probability in the laboratory environment close to 100% at a distance of up to 3 m for the tested samples of explosives and metal objects hidden under cloth.

FMCW MM-wave non-imaging sensor for detecting hidden objects

MM-wave sensor operating at 94 GHz has been developed for detecting hidden objects such as weapons, explosives etc. It is based on a frequency modulated continuous wave (FMCW) and includes the two high gain horn-lens antennas integrated with a homodyne transceiver. The synthesized linear FMCW signal in Ku-band is multiplied by a factor 6 to generate the transmitted signal at 94 GHz. An intermediate frequency (IF) signals obtained in the output port of the mixer is employed for detecting hidden objects. Post detecting procedure was performed using and MatLab processing. Experiments have demonstrated an efficiency of the designed sensors for homeland security applications.

Microwave Characterization of Powders Using Multiresonance Cell

This paper describes the microwave characterization of powders using a multiresonance cell supporting TE10p modes in a rectangular cavity. An identification of the resonating modes excited in the cell has been done in order to extract the real and imaginary parts of a complex dielectric constant of the material under test. Calibration of the cell has been performed using the empty resonator. An error analysis was employed in order to estimate the uncertainty caused by coupling elements needed to connect the measuring cell with a network analyzer. The CST Microwave Studio solver was used to evaluate degrading measurement accuracy caused by a presence of coupling elements. Comparison of the measured data with 3-D electromagnetic simulation has demonstrated a good agreement. The validation of the method described has been done for the α-lactose monohydrate powder as a tested material at X-band. The role of density of powder has been estimated too. The same approach can be easily extended to the microwave characterization of other powder materials.

Microwave diagnostics of some bio-medical solutions using cylindrical resonator

The paper describes results of testing the microwave sensor designed for diagnostics of some bio-medical solutions. It consists of a resonator supporting quasi-TM010 or TE111 modes containing an axial glass tube filled with the solution under test. Concentrations of the tested ingredients in water solutions both organic and inorganic have been determined with high accuracy. Various solutions have been tested including: sodium chloride, magnesium sulfate, sodium bicarbonate, kali permanganate, glucose, human Cerebral Spinal Fluid-CSF etc. CST Microwave Studio simulator was used to design the sensor. The suggested sensor can be easily integrated with an on-line system controlling concentrations of various bio-medical solutions.

Density-independent moisture measurements of polymer powders using a mm-wave quasi-optical resonator

A quasi-optical resonator is implemented to characterize low loss polymer powders at mm waves. Based on the suggested resonator configuration, density-independent moisture measurements have been carried out in W-band. The resonant frequencies and Q factor were measured to reconstruct the real and imaginary parts of a dielectric constant to be used for moisture determination. The model needed to describe this quasi-optical resonator including the reconstructing algorithm has also been developed. An example illustrating the method proposed is reported.

Quasi-noise illumination in mm-wave imaging: From concept to realization

The paper describes the W-band single-pixel imaging de tector with a pulse-noise source in the Tx-channel and the direct detecting circuitry in the Rx-channel. The detector is maintained on X-Y programmable scanner controlled by LabView interface which is integrated with MatLab used for online image reconstruction. The application of an incoherent illumination generated by the frequency-limited quasi noise source improves image quality compared with the coherent mode widely used in conventional active imagers.