Accession Number:

ADA231495

Title:

UHF Model Simulation of Detecting Voids in a Dielectric Medium Using HF- VHF Airborne Short-Pulse Radar

Descriptive Note:

Corporate Author:

COLD REGIONS RESEARCH AND ENGINEERING LAB HANOVER NH

Personal Author(s):

Report Date:

1990-12-01

Pagination or Media Count:

18.0

Abstract:

A model study of the interaction between airborne-launched short- pulse radar signals and three sizes of rectangular voids in bedrock was conducted to see if polarization perpendicular to the strike of the voids could be used for detection, and if any characteristic waveform such as resonance could be associated with any of the void responses. Radar wavelets with frequency spectra centered at about 870 MHz illuminated three square Styrofoam relative dielectric constant less than 1.1 strips, 5, 10 and 20 cm on a side, emplaced in a sand relative dielectric constant of 5.9 box, 1 m deep, 4.5 m long and 2.5 m wide. This setup modeled the interaction of 22-, 44- and 87-MHz wavelets with voids having widths of 2 m and situated in a crystalline type of bedrock. the antennas traversed 23-85 cm above the sand surface and data were recorded continuously at 25.6 scanss. Polarization both parallel and perpendicular to the long axis of the voids produced reflections with apparently undistorted wavelets and hyperbolic spatial distributions, with the strongest response for the perpendicular over the 10-cm void. Although real HF signal attenuation was not simulated in the model, the results suggest that under these nearly ideal conditions of a homogeneous void matrix of low conductivity with a flat surface, a 2-m void at a 10m depth could be detected easily with a moderately powered transmitter ate a 10- to 12-m altitude using a 40- to 50-MHz short pulse polarized perpendicular to the void axis.

Subject Categories:

  • Active and Passive Radar Detection and Equipment

Distribution Statement:

APPROVED FOR PUBLIC RELEASE