E. Kennaugh

Bio: E. Kennaugh is an academic researcher from Ohio State University. The author has contributed to research in topics: Waveform & Bistatic radar. The author has an hindex of 4, co-authored 4 publications receiving 163 citations.

The K-pulse concept

Abstract: Two general classes of inversion techniques may be distinguished: those utilizing angular or spatial frequency analysis over as wide a range of target aspects as practicable, and those involving relatively few aspects but employing as wide a frequency spectrum as possible. The latter technique is discussed, and a special excitation waveform called the "kill-pulse" or K-pulse is proposed. By analogy with lumped and distributed networks, a unique aspect-invariant excitation waveform is postulated for an isolated scatterer. This waveform, of finite and minimal duration, then characterizes the pole spectrum of the scatterer as used in the singularity expansion method (SEM) or for target identification. The derivation of this excitation waveform and its relation to one or more surface waves is illustrated by several examples. Using surface waves initiated at certain points of an object, the complex attenuation of circumnavigating waves is estimated by the geometrical theory of diffraction. Three-parameter characteristic equations are derived which predict pole strings with excellent accuracy for conducting spheres and cylinders and lesser accuracy for prolate spheroids of several axial ratios. For spheres and cylinders, the same characteristic equation also yields good estimates of cavity resonance frequencies.

Polarization dependence of RCS--A geometrical interpretation

Abstract: The variation of back-scattered radar cross section (RCS) with common transmit-receive polarization P is given by a simple geometrical construction on the Poincare sphere

The K-pulse and response waveforms for nonuniform transmission lines

Abstract: Application of the K-pulse concept to a class of distributed-parameter systems which can be modeled by finite lengths of nonuniform transmission lies is demonstrated. The K-pulse of such a system is the excitation (input) waveform of finite duration which yields response waveforms of Finite duration at all points of the system. Numerical techniques using a finite element method are developed to derive accurate approximation of the K-pulse and response waveforms for uniform and nonuniform transmission lines. Comparison is made with exact results to illustrate the accuracy and utility of the method.

Theory and measurement of backscattering from RFID tags

Abstract: This paper presents a method for measuring signal backscattering from RFID tags, and for calculating a tag's radar cross section (RCS). We derive a theoretical formula for the RCS of an RFID tag with a minimum-scattering antenna. We describe an experimental measurement technique, which involves using a network analyzer connected to an anechoic chamber with and without the tag. The return loss measured in this way allows us to calculate the backscattered power and to find the tag's RCS. Measurements were performed using an RFID tag operating in the UHF band. To determine whether the tag was turned on, we used an RFID tag tester. The tag's RCS was also calculated theoretically, using electromagnetic simulation software. The theoretical results were found to be in good agreement with experimental data

Polarization diversity in radars

Abstract: Polarization, together with the amplitude, time, frequency, phase, and bearing descriptors of radar signals, completes the information which can be obtained on target returns in monostatic radars. The exploitation of information on the echo polarization state through polarimetric radars is currently a subject of interest, due to theoretical and technological advances, as well as to the development of new radar applications. Many polarization techniques, which have been proposed and analyzed to enhance radar performance, are reviewed in this paper in order to assess the possible improvement they can provide in the signal-to-disturbance ratio, target detectability, target discrimination and resolution, and target classification and identification. Some recent experimentally based results relating to these applications are also presented. Those techniques are emphasized for which polarization-based capabilities appear sufficiently assessed, such as adaptive polarization cancellation of clutter, chaff, and jamming. Polarization Doppler processing of dual-polarization radar signals, meteorologic applications, and polarization adaptation for target detection in the clear (in free space) are also examined.

The singularity expansion method and its application to target identification

Abstract: The singularity expansion method (SEM) for quantifying the transient electromagnetic (EM) scattering from targets illuminated by pulsed EM radiation is reviewed. SEM representations for both induced currents and scattered fields are presented. Natural-resonance-based target identification schemes, based upon the SEM, are described. Various techniques for the extraction of natural-resonance modes from measured transient response waveforms are reviewed. Particular attention is given to the aspect-independent (extinction) E-pulse and (single-mode) S-pulse discriminant waveforms which, when convolved with the late-time pulse response of a matched target, produce null or mono-mode responses, respectively, through natural-mode annihilation. Extensive experiment results for practical target models are included to validate the E-pulse target discrimination technique. Finally, anticipated future extensions and areas requiring additional research are identified. >

Ground penetrating radar as a subsurface environmental sensing tool

Abstract: Ground penetrating radar (GPR) is considered as an environmental tool. The basic concepts involved in GPR are introduced briefly including the antennas, propagation, target scattering, and mapping. Target identification is important when using GPR since the scatterer can only be observed by evacuation. This is discussed in terms of mapping and complex natural resonances. GPR has been used and is being considered as a tool for the detection of a wide variety of subterranean features. A very brief description of the various applications of GPR is presented. In terms of environmental sensing, it has been applied to detect buried tanks, landfill debris, water levels, and contaminated fluids. The detection of various military devices also represent a serious environmental concern including landmines and unexploded ordnance. There are also possible applications involving the detection of buried utilities highway voids, grave sites. It has been used for examining archeological sites. The above list is far from complete because of the ever-expanding use of GPR. >

Radar target discrimination using the extinction-pulse technique

Abstract: An aspect independent radar target discrimination scheme based on the natural frequencies of the target is considered. An extinction-pulse waveform upon excitation of a particular conducting target results in the elimination of specified natural modal content of the scattered field. Excitation of a dissimilar target produces a noticeably different late-time response. Construction of appropriate extinction-pulse waveforms is discussed, as well as the effects of random noise on their application to thin cylinder targets. Also presented is experimental verification of this discrimination concept using simplified aircraft models.