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This paper presents a study of the prerequisites and the original way of transition from a quasi-monostatic antenna system to a monostatic one as applied to ultrawideband pulsed contact radar subsurface sounding at shallow depths. For this purpose, the joint application of ultrawideband electric "Bow-Tie" and magnetic "Bi-Quad" antennas is investigated. The mutual arrangement proposed in this work allows reducing to zero the distance between the centers of the antennas in the plane orthogonal to the direction of signal emission-reception. The results of full-scale tests with the corresponding processing of the obtained ensembles by the example of probing the human body for the detection and determination of the parameters of biological rhythms and a tree trunk 58 cm in diameter showed satisfactory results for the radar with a central frequency of 1.5 GHz. At the same time, the suppression of the useful signal received due to the application of the described design was only 2.3 dB at an acceptable level of the direct signal, which does not lead to overloading of the radar stroboscopic receiver input. [ABSTRACT FROM AUTHOR]

In the proposed work we investigate the possibility of measuring a complex resistance remote by several meters, in particular the parallel connection of an active resistance and a capacitor. The measurement is made at a frequency of one megahertz. Since the unknown complex resistance is connected to the measuring equipment by a radio-frequency cable, the theory of long lines is used in deriving the formula. Examples of practical application of the algorithm for measuring human skin resistance are given. [ABSTRACT FROM AUTHOR]

In this work, the possibility of determining the geometric shape of the cross section of dielectric objects in the case of a priori information on their internal homogeneity or detecting integral internal inhomogeneities in the case of a priori information on the geometric shape of the cross section via the transmission sensing of these objects with ultra-wideband pulse radars with a central frequency in the spectrum of pulses on the order of 1 GHz is investigated. [ABSTRACT FROM AUTHOR]

For the classical peak detector built on modern electronic components and designed to measure the amplitude of nanosecond pulses, an equivalent circuit, which additionally includes parasitic capacitors and inductances, is mathematically described using the Laplace transform. Based on the results of analyzing the characteristics of the equivalent circuit, some recommendations are made to improve measurement accuracy when it is possible to reduce the limit on the duration of measured pulses. [ABSTRACT FROM AUTHOR]

The article proposes and studies a mathematical model for the determination of the basic electrophysical properties of a dielectric object presented as a single layer with ground-penetrating radar signals. The model algorithm uses the values of reflection amplitudes from the front and rear edges of the object, their ratio, and the mutual time shift as the main initial physical data to find the relative permittivity of the studied object and the loss tangent. [ABSTRACT FROM AUTHOR]

This article describes a classic ground-penetrating radar, which includes a transmitter on two step-recovery diodes for the shock excitation of an ultra-wideband Vivaldi antenna, a discrete sampling receiver with data transmission via Ethernet mounted on a six-blade unmanned aerial vehicle, experiments and processing results of the obtained signals for detecting the movement of small objects both in open space and behind a wall, as well as calculations to determine the thickness of the sounded walls in the case of a single measurement scenario. [ABSTRACT FROM AUTHOR]

This paper describes mathematically an expanded circuit additionally containing parasitic capacitors and inductors for the pulser circuit on two SRDs, which allows a relatively wide range to vary the output pulse duration with a rise time and fall time of less than a nanosecond. Resolving a system of differential equations, we acquire a possibility of analyzing the influence of the circuit elements on the output pulse parameters and to select the optimum value. The calculation results are compared with experimental data. [ABSTRACT FROM AUTHOR]

Sawtooth voltage with the possibility of changing its nonlinearity was modeled for a stroboscopic signal converter used in pulsed ultrawideband gigahertz sensor locators. The pattern of automatic shift in signal sample pulses is described mathematically, on the basis of which the formula of the law of shift in the aforementioned pulses at a nonlinear fast sawtooth voltage has been obtained. The effect of the nonlinearity of sawtooth voltage on the output signal of the stroboscopic converter is shown. [ABSTRACT FROM AUTHOR]

Abstract—: The paper describes the operation of a classic step-recovery-diode-based pulse generator circuit using differential equations. The circuit has parasitic inductances and capacitors for both circuit elements and the diode in addition to standard discrete elements necessary for pumping the diode and generating a sharp edge. The results are compared with experimental data. [ABSTRACT FROM AUTHOR]

The possibility of applying the first principal component of the Karhunen-Loeve transform to localize reflections from a moving object on the time axis by sondaging with an ultra-wideband locator is studied. [ABSTRACT FROM AUTHOR]

The possibility of achieving the maximum level of the probe pulse spectrum at a fixed frequency when selecting the optimal duration of the excitation pulse of the radar with pulse excitation antenna has been investigated. [ABSTRACT FROM AUTHOR]

Experiments have been carried out on strobe converters based on transistors and tunnel diodes with frequency bands at 1500 and 4500 MHz, correspondingly. The problem of determining the pulse characteristic was solved using measuring tables of the input and output signals. The input signal was measured in the form of a sharp jump by a broadband strobe oscilloscope with a frequency band of up to 20 GHz. The task of signal restoration was solved by the known frequency method using estimated impulse response. This signal processing has allowed to expand the frequency range of investigated converters. [ABSTRACT FROM AUTHOR]

A possibility of determining active and reactive components of a two-terminal network using the Fourier transform is studied. The initial time dependencies of the current and voltage pulses are approximated by Gaussian wavelets and power series of different orders. Restrictions on the computation accuracy and time are determined. [ABSTRACT FROM AUTHOR]

In this paper, we research an indirect method of measuring the complex impedance at the end of a long line, in particular the feed impedance of wideband antennas. The method is based on a spectral analysis of incident and reflected pulses. The method is shown to be useful for certain restrictions on measuring active and reactive components in a band up to several gigahertzes. [ABSTRACT FROM AUTHOR]

The effectiveness of combining correlation of the signal reflected from the object with principal component analysis is investigated, for radar applications-in particular, ultrawide-band (UWB) bioradar systems such as remote contact-free detection and recording of human respiration. Simulation and physical experiments are employed. The signal/noise ratio for which it is advisable to use correlation of signal with reference signal is determined. [ABSTRACT FROM AUTHOR]

Using model and real signals, the possibility and appropriateness of low-frequency component (trend) filtering using singular spectrum analysis (SSA) based on principal component analysis is considered. The real signals are represented by human breathing curves obtained after processing of UWB (ultrawideband) impulse signals using the principal component analysis. It has been shown experimentally that the use of the SSA makes it possible to suppress an interfering trend down to 18 dB. [ABSTRACT FROM AUTHOR]

This paper considers the possibility to employ the first principal component (Kahrunen-Loeve transform) to reveal the law of reflected signal phase modulation. The processing of modeled and real signals representing ultrawideband impulses reflected from a simple target and from a model imitating human breath was taken as an example. It is experimentally shown that, for small movements of the target, the first principal component's movement trajectory follows the original law of reflected signal phase modulation with precision of not less than 20%. [ABSTRACT FROM AUTHOR]

An application of the Karhunen-Loeve transformation (principal component analysis) to the extraction of the signal corresponding to small breathing displacements of the human chest is illustrated by the example of the ultrabandwidth impulse reflected from a simple human target. The reduction in the dimensions of the original signals from 256 to 5 is shown by experiments to take place in the case of small displacements and the mean-square error not exceeding 10%. [ABSTRACT FROM AUTHOR]

The possibility of data smoothing for the amplitude-frequency band control of oscilloscopes and signal converters is studied. It is shown that data smoothing by third-order splines differs slightly in performance compared to smoothing by a series of shifted functions Erf( t − Δ t). [ABSTRACT FROM AUTHOR]

number of ultra-wide-band pulse sharpers are studied in which semiconductor devices with different physics of fast switching are used. The results of full-scale tests of the sharpers and the spectral estimates of the generated pulses according to two models are given. [ABSTRACT FROM AUTHOR]

The possibility of shaping pulses by an impact avalanche transit-time diode operating in the abnormal mode is studied. A schematic diagram realizing the pulse shaping is presented. The results of environmental tests of the circuit and results of simulation demonstrating the efficiency of the proposed mode for obtaining pulses with picosecond leading edges are given. [ABSTRACT FROM AUTHOR]