M. Gashinova

Artificial dielectric medium possessing simultaneously negative permittivity and magnetic permeability

An artificial dielectric medium comprising two sublattices of spherical particles made of a high-dielectric-constant (high-ε) material, which are embedded into a low-ε dielectric matrix, are considered. Particles belonging to different sublattices have different diameters. It is shown that the properties of this composite structure are equivalent to those of an isotropic medium possessing a negative refractive index (n < 0) in the vicinity of frequencies at which the H111 and E111 oscillation modes exhibit simultaneous resonance in particles of different diameters, which leads to the appearance of electric and magnetic dipole moments, respectively. Averaging of these dipole moments over the volumes of cells formed by the corresponding spherical particles determines their contributions to the permittivity and magnetic permeability of the composite medium. At frequencies above the resonance, both contributions become negative and, hence, the medium exhibits simultaneously negative values of the permittivity and magnetic permeability. The proposed composite structure consists only of dielectric components. Spherical particles with εd > 200 can be made of a ferroelectric material.

Optimal Signal Processing in Ground-Based Forward Scatter Micro Radars

The received signal in forward scatter radar (FSR) depends on the targets electrical size and trajectory, which are unknown a priori. As a result, in practical situations, it is impossible to obtain the accurate reference function at the reception side, and adaptation of optimal filtering is therefore proposed for this case. This paper presents a signal processing algorithm for ground target detection using FSR, which includes the construction of the adaptive reference functions and the identification of target velocity and its observation time. Furthermore, the algorithm performance is analytically determined under practical motion trajectories such as different motion directions and baseline crossing points, which indicate the effectiveness of the proposed algorithm in a practical case for FSR. The effectiveness of the algorithm is shown using both simulated and experimental data. Finally, the resolution in convoy targets in ground-based FSR is analytically obtained for the first time; the resolution is totally different from the resolution in conventional radar theory because of the target signature characteristics in ground-based FSR. The majority of the analytical results are verified experimentally.

UWB signature analysis for detection of body-worn weapons

Presented work is dedicated to the study of innovative principles, which can be used for the remote detection of concealed, body-worn weapons & explosives (CW&E). The approach is based on the analysis of the late time response (LTR) of the human body illuminated by a UWB signal: if CW&E are attached to the body it will essentially influence the LTR characteristics. A set of LTR parameters represents the unique signature of target. Our aim here is to demonstrate the ability of the developed approach to extract and to interpret the signature. In order to validate a feasibility of the approach analytical consideration, full-wave modeling and initial experiment have been implemented and results have been compared

Empirical model of vegetation clutter in forward scatter radar micro-sensors

Spectral and statistical properties of measured vegetation clutter are analyzed for ground-based forward scatter radar (FSR) sensors operating in VHF/UHF bands employing omni-directional antennas. The empirical computer simulation model of vegetation clutter is proposed.

Maritime UWB forward scattering radar network: Initial study

A scenario for an ultra-wideband (UWB) forward scattering radar (FSR) network for detection of low radar cross section (RCS) maritime surface targets is suggested. A chain of buoys equipped with transceivers which forms a FSR for target detection is considered. In this paper, the first stage of the study is described and major aspects of future work are discussed. It was shown that the high level of surface clutters related to FSR might be reduced by utilisation of UWB technology. As a preliminary further investigation, a numerical simulation of the 3-D RCS for comprehensive models of small maritime targets is obtained and comparisons with simplified target models are made.

High-T/sub c/ superconducting planar filter with pseudo-Chebyshev characteristic

This paper presents design and measurement results of a high-T/sub c/ superconducting planar filter based on a pair of coupled modified hairpin resonators considered to be a key constituent of the filter structure. This provides the filter characteristics, which are very close to the Chebyshev prototype of the same order.

Multistatic Forward Scatter Radar for accurate motion parameters estimation of low-observable targets

This paper introduces the MIMO Forward Scatter Radar (FSR) concept to provide an accurate estimation of the motion parameters of a low observable target. In particular, two techniques are introduced to obtain the estimate of the target velocity component normal to the TX-RX baseline, that exploit the multiple transmitters and receivers. Experimental results allow the comparison of the efficiency of the two approaches and demonstrate the potential of MIMO FS configuration.

Antenna range evaluations of low THz imagers for automotive applications

In this paper the requirements for low-THz automotive sensors are presented with the focus on THz imaging of the terrain in front of the vehicle. Initial imaging performance at 150 GHz radar is demonstrated and a planned extension using an advanced 300 GHz radar system is described. Antenna requirements for these systems are discussed.

Ultra-wideband forward scatter radar fence for maritime surveillance — Initial experimental results

The work described in this paper is a continuation of previous analytical work that has progressed to an experimental phase. The paper discusses the development of an ultra-wideband (UWB), forward-scatter radar (FSR) system for the detection and (ultimately) automatic recognition of low reflectivity maritime targets. Here we present the concept, developed hardware and selected initial experimental results. A number of novel ideas have been developed to reduce cost, size, prime power requirement, complexity and utilise the advantages of FSR operation. System benefits include increased target cross section (over conventional bi/monostatic radar), increased target detection capability, robustness to stealth targets, decrease in sea clutter effects from synthesis of extremely narrow beams whilst using omni directional antennas and sub-Hertz Doppler frequency measurement capability. The experimental work investigates the use of an UWB FSR fence for security, UWB propagation measurements, UWB sea clutter measurements at very low grazing angles, UWB spectral coverage and the synthesis of narrow beamwidth antennas using forward scatter pulse transmission.

FSR velocity estimation using spectrogram

This paper focuses on the estimation of target motion parameters in forward scatter radar. A new method based on the use of the Doppler signature spectrogram has been investigated. This allows a rough estimation of target motion parameters even in the presence of significant clutter, when the Doppler signature cannot be used to extract accurate kinematic information. The spectrogram characteristics change depending on targets speed, crossing angle and crossing point, this will be shown in order to explain how it is possible to estimate kinematic information analyzing the spectrogram trend. The performance of this new method is analyzed at the initial stage of the research.