A numerical method to invert the dielectric permittivity profile from Riccati equation using Newton-Kantorovich iterative scheme is described. Instead of handling equations in terms usual geometrical depth, we determine as a function electromagnetic path length since convergence and stability solution are found be significantly better this case. The initial used starting point for inversion obtained by another employing successive reconstruction interfaces homogeneous layers step-like form....

The antenna system of ground penetrating radar is usually positioned in the vicinity surface to obtain sufficient spatial resolution for detecting small targets. Therefore, received signals are subject errors caused by unwanted reflections and coupling. A near-field calibration procedure taking into account these effects as well dispersion presented. For practical convenience, only a metal plane used here standard. Calibration data measured set distances between plane. reference all...

This paper presents a modified signal processing technique of differentiating buried targets using impulse ground-penetrating radar. The is applicable to radargram; however, carried out for each trace the radargram separately. Every significant peak compared with some calibration signal, example, that reflected from far interface thick rock slab. However, does not require reference material be embedded in medium, it can air. difference phases between object and function slowly varying time...

Progress in terahertz spectroscopy and imaging is mostly associated with femtosecond laser-driven systems, while solid-state sources, mainly sub-millimetre integrated circuits, are still an early development phase. As simple cost-efficient emitter as a Gunn oscillator could cause breakthrough the field, provided its frequency limitations be overcome. Proposed here application of recently discovered collapsing field domains effect that permits sub-THz oscillations sub-micron semiconductor...

Ultra-wideband antennas for subsurface imaging are usually heavily loaded to widen the frequency band of operation and reduce clutter caused by antenna ringing. The paper presents two designs tapered-slot in which ringing has been partially suppressed corrugations and/or resistive films applied on flares. It was found that loading flares diminishes return loss increases its directivity at low frequencies cost some drop efficiency. In addition, reduces coupling transmitting-receiving pair...

This article presents a time-domain imaging technique for layered dielectric slabs using solid-state wavelet generator with subterahertz carrier frequency. The utilizes the dual nature of wavelet, i.e., both applicability time-of-flight measurements and ability wavelets to interfere in thin layers at frequency that is preserved spite ultrawideband character signal. results very high sensitivity time delay resultant pulse variations effective thickness (thickness × refractive index) layer. It...

A novel Wideband tapered-slot antenna for GPR applications is proposed. conventional approach to reduce unwanted interactions between the and ground surface requires extensive microwave absorbers treatment. For same purpose we propose use corrugations along edges. The improve directivity wideband matching of with free space retaining also good radiation efficiency. Further improvement performance has been achieved by patching corrugated areas resistance card strips. elimination foam-type...

Results of further development a new two-parameter microwave imaging method for both detection and discrimination subsurface targets are presented. The is based on the derivation two B-scans from initial B-scan data, separately amplitude phase. Then, these combined in common image using rule that data governs intensity pixels whereas phase determines their colors. In this work, modified technique building accounts better frequency dependence wave reflected buried object may be caused by...

A new method is developed to reconstruct the permittivity profile of a dielectric slab in guided wave formulation. The propagation constants eigenmodes are used as input data for inversion boundary-value problem nonlinear differential equation representing condition existence modes. expanded into set special functions so that constant particular mode depends mainly on only one term set. This ensures fast convergence an iterative procedure find coefficients expansion. shown be valid...

Several designs of tapered-slot antennas for ultra-wideband applications such as ground penetrating radar are described. The subsurface imaging must be damped to decrease clutter arising from the ringing antenna. is caused by internal or open-end reflections well multiple between antenna and surface. In proposed design, has been partially suppressed corrugations and/or resistive films applied on flares in different ways. Performance estimated using electromagnetic simulation software. It was...

The problem of target discrimination in ground penetrating radar data (GPR) is addressed this study. Formerly developed frequency-domain technique based on building separate amplitude and phase profiles for every A-scan has been modified to be suitable also impulse GPR data. To end, have preprocessed transformed frequency domain. rest the algorithm rather similar case method yields a profile as function depth that related shift occurring act reflection wave from inhomogeneity existing at...

In this work, performance of a novel two-parameter method microwave subsurface visualization has been studied with the use experimental data. The is based on building image area in which amplitude data govern intensity pixels whereas their color associated phase information. understood here as shift related to reflection act from buried object. As depends dielectric properties target, one can distinguish targets by profile. It shown that images different objects built differ considerably...

A novel signal processing method to build radargram for a step-frequency radar is presented. The conventional technique of obtaining that employs an inverse Fourier transform separate A-scans has been modified by the derivation additional time-dependent function. To this end, performed on both measured complex reflection coefficient data and also same in which phase term replaced one representing only distance target. difference arguments obtained functions yields desired depending mostly...

Theoretical and experimental studies of the influence mutual arrangement wideband tapered slot antennas (TSA) in array are presented. Major attention is paid to reducing antenna coupling. The modeling was done using a transient solver realized CST Microwave Studio software. It found that parallel displacement when distance between planes kept, allows suppress unwanted lateral coupling leads turn reduction clutter. consisting TSA had been fabricated tested test site for detection...

Antennas and antenna systems are the most important components of ground penetrating radar. That is why a lot work had been done in field modeling design. One major points about working vicinity to ensure stability characteristics influence nearby objects surface. This devoted comparison performance different GPR antennas such as TEM horn, dielectric rod fed by horn tapered-slot operating part step-frequency Presented have developed manufactured authors framework international projects. In...

In this article, we present the possibility of using terahertz time-domain spectroscopy to detect trace, ppm-level (%wt.) concentrations admixtures in 95-octane lead-free gasoline straightforward time-of-flight (pulse-delay) measurements performed directly liquid. The method was tested on samples containing 75–0.0125% isopropanol and 0.3–0.0250% water. detection limits for water content were determined be 125 ppm 250 ppm, respectively, approaching much more complicated time-consuming methods...

A modified bow-tie antenna consisting of two semicircle flares fed by a tapered microstrip line is described. Such design allows avoiding separate impedance transformers and baluns that are often poorly matched over the wide frequency band operation resulting in considerable late-time ringing. The using one as ground plane used to transform 50 Ohm feeding cable around 100 Ohm. performance was tested experimentally concrete member made heavy density with metal rod inserted near its center....