J.E. Ross

Investigation of Simulated annealing, ant-colony optimization, and genetic algorithms for self-structuring antennas

A self-structuring antenna (SSA) is capable of arranging itself into a large number of configurations. Because the properties of the configurations are generally unknown at the onset of operation, efficient search algorithms are required to find suitable configurations for a given set of environmental and operational conditions. This paper investigates the use of ant-colony optimization, simulated annealing, and genetic algorithms for finding suitable antenna states. The implementation of each algorithm for SSA searches is described, and the performance of each algorithm is compared to a random search.

Performance of an automated radar target discrimination scheme using E pulses and S pulses

Previous studies have demonstrated the viability of natural resonance based target discrimination using extinction pulses (E pulses) and single-mode pulses (S pulses). These studies qualitatively demonstrated the principles of resonance annihilation by forcing the interrogating pulse to have zeros at the complex natural resonance frequencies of the target. Here a quantitative scheme for evaluating discrimination using the E pulse and the S pulse is given. The performance of an automated E-pulse and S-pulse discrimination scheme is evaluated using numerically derived scattering data with varying amounts of noise. >

Self-structuring antennas

This paper introduces a new class of antennas, called self-structuring antennas (SSAs). An SSA has the ability to alter its electrical shape in response to changes in its environment. This property makes an SSA suitable for use in a number of traditionally difficult antenna situations. The basic principles of the SSA are introduced, and a number of potential applications are highlighted. Details of a simple prototype antenna are provided. Computer tools capable of analyzing the SSA are described, and results of both numerical and experimental investigations of the SSA are presented.

Radar target identification using a combined early-time/late-time E-pulse technique

The E-pulse technique has been applied in the past to both the early- and the late-time components of a transient radar response. While the late-time E-pulse technique uses aspect-independent waveforms, the early-time E-pulse technique requires a separate waveform for each target aspect angle and thus significantly more storage and processing time. This paper discusses a combination of the two techniques that employs the early-time technique to remove ambiguities generated from application of the late-time method. By narrowing the possible range of aspect angles of the potential targets, the early-time technique can be employed more efficiently.

A general E-pulse scheme arising from the dual early-time/late-time behavior of radar scatterers

A duality between the temporal late-time response and the spectral early-time response of a radar target is used to form the basis for a general E-pulse technique. Examples, using the ultrawide-band measurements of an aircraft model, reveal that E-pulse cancellation is possible both in the time domain for the late-time component and in the frequency domain for the early-time component. Applications to radar target discrimination and clutter cancellation are described, and the aspect dependence of early-time discrimination is investigated. >

A radar target discrimination scheme using the discrete wavelet transform for reduced data storage

A correlative radar target discrimination scheme using the transient scattered-field response is proposed. This scheme uses a one-dimensional discrete wavelet transform on the temporal response to reduce the amount of data that must be stored for each anticipated aspect angle. Experimental results show that a reduction in stored data of sixteen to one still allows accurate discrimination in adverse noise situations with signal-to-noise ratios as low as -5 dB. >

Time-domain imaging of airborne targets using ultra-wideband or short-pulse radar

A time-domain physical optics inverse scattering identity is derived for real-time use in ultra-wideband radar systems. It is shown that using the band-limited impulse response of a radar target provides an edge-enhanced image. A simulation based on stepped-frequency, multiaspect measurements of aircraft models produces clear images with highly-defined edges. >

Self-structuring antenna for television reception

This paper investigates the use of a self-structuring antenna for television reception. Information about the received signal strength is obtained from the automatic gain control circuit of the television and used to determine the appropriate antenna structure. Because of the large number of possible configurations, a genetic algorithm is used to search for optimal switch arrangements. The antenna template and software were developed by undergraduate students at Michigan State University; refinement of the antenna by a core group of undergraduates is currently being undertaken.

Measurement and processing of scattered ultrawideband/short-pulse signals

High quality ultrawide-band measurements provide a basis for understanding the transient scattering phenomena necessary for the development of short-pulse radar target identification and detection schemes. This paper describes several techniques used at Michigan State University (MSU) for the acquisition, processing, and interpretation of ultra-wideband scattering data. By performing measurements over a sufficiently large bandwidth, the early- time specular nature of a radar target and the late-time resonant behavior can be observed simultaneously within a single target signature. Special attention has been given at MSU to enhancing the equivalent bandwidth of the measurement system through a spectral slicing and extrapolation method. Observation and interpretation of the various scattering phenomena and their dependance on target aspect are then interpreted through several visualization techniques, including scattering plots, frequency-time plots and images.

Self-structuring antenna concept for FM-band automotive backlight antenna design

The study of the SSA has shown much promise for use in an automobile environment; however, the addition of the necessary switch technology adds a new level of complexity to existing antenna systems. Some of the benefits of the SSA can be obtained with existing systems by using the SSA concept to design a fixed antenna. This work uses the principles of self-structuring antennas to design a fixed automotive backlight antenna. A genetic algorithm (GA) is utilized in this design, with a cost function optimizing both VSWR and gain