Louis L. Nagy

Electromagnetic reflectivity characteristics of road surfaces

Advances in the design, development, and fabrication of key microwave components along with those in electronics have resulted in growing optimism about the application of radar technology to solving the automotive highway collision problem. However, before an automotive radar system can be fully realized, a major effort will be required to define the environment in which the system must operate, and to obtain a fundamental understanding of the influence of these RF parameters. One such parameter which will have a considerable effect on the design of automobile radars is that due to the presence of natural and man-made surfaces within the beamwidth of the antenna. Generally, the presence of such a surface will result in incident RF energy being reflected off the surface in a forward direction and some portion being scattered in a backward direction. This paper presents the results of a program which was designed to measure this type of reflectivity characteristic for common road surfaces. Measured data are presented along with a theoretical study demonstrating the influence that this phenomenon can have on highway collision radar systems.

An electric-field uniformity study of an outdoor vehicular test range

This paper describes an electric-field uniformity evaluation of an outdoor automotive antenna test range. Electric-field uniformity results are generated from accurate, full-wave electromagnetic simulations of the test range. Measured electric-field results using an ultra wideband measurement system are also presented. The simulations and measurements indicate that the turntable has a significant influence on the field uniformity.

An ultrashort pulse radar sensor for vehicular precollision obstacle detection

An ultrashort pulse radar sensor was designed, developed, and fabricated for an automotive hazard evaluation program. Tests verified that this unique system, which had a pulse duration of approximately 1 ns, did meet its design goals. Reflectivity characteristics of several road surfaces and RF scattering cross sections of selected highway objects were measured. Experiments verified the capability of the system to identify one object from another, even for a multiple object environment. An analytical model was developed that describes the Fresnel region scattering characteristics of simple objects.

Diplex Doppler radar for automotive obstacle detection

The usefulness of radar as an automotive obstacle detection system is currently being investigated. Possible applications of such a system presently are automatic braking and air bag actuation and eventually the totally automatic highway. One type of radar having possible potential for these short range applications is diplex Doppler radar. The microwave and electronic circuits basic to a diplex Doppler radar obstacle detection system are described in this paper. The system provides Analog outputs proportional to range, velocity, and time to impact relative to an obstacle, as well as indicating whether the velocity is opening or closing.

Outdoor vehicular test range turntable impact on electric-field uniformity study

This paper describes an electric-field uniformity evaluation of an automotive manufacturerpsilas vehicular antenna range. Dipole measurements, vehicle gain measurements, ultra wideband measurements, and two independent electromagnetic simulations were performed to determine field uniformity characteristics of the antenna range. The simulations and measurements indicated that the turntable significantly influenced the sitepsilas field uniformity. It was determined that increasing the size of the metallic turntable degraded the field uniformity performance of the range. Ideally, the size of a metallic turntable should be minimized to maximize field uniformity performance.

AUTOMOBILE RADAR SIGNATURE STUDIES

Continuous wave (CW) scattering measurements have been made in a manner which is consistent with automobile radar operation. Various aspects of simple targets and of an automobile were measured in a microwave anechoic chamber. Both horizontal and vertical linear polarizations were transmitted and their co-linear and cross polarizations received. These data have been used to confirm the existence of and to understand certain scattering mechanisms. They have also been subjected to analyses in order to determine the ability to discriminate among the various simple targets. It is demonstrated that even a simple analytical method shows discrimination capability among the targets tested. /GMRL/