Antenna development and a stepped-frequency GPR system for landmine detection
A project for developing a compact size GPR system for landmine detection was started. It will be based on stepped-frequency radar system for wider application in various kinds of soil conditions. We have developed a prototype stepped-frequency for fundamental evaluation of the system. This system uses a broadband Vivalidi antenna and operates at 2-6 GHz. The system was tested in laboratory and could be used for imaging buried mine-like targets by high resolution. Series of tests were carried out by using sand with rough surface and inhomogeneous soil. We discuss the ability of GPR for landmine detection.
Microwave Enhanced IR Detection of Landmines Using 915 MHz and 2450 MHz
Abstract : As a continuation of previous studies in microwave enhanced infrared (IR) detection of landmines at DRDC Ottawa, additional experiments were performed using a microwave source at 2450 MHz to illuminate buried inert antipersonnel and antitank landmines. Further experiments were performed for the first time using a microwave device at 915 MHz with an open waveguide. Infrared detection was accomplished using a FLIR A20M IR camera in the 8-12 mm region. An investigation of this method was done by examining mine signatures made up of two components: the microwave interference on the surface of the sand caused by the superposition of incident and reflected microwave beams, and the microwave absorption by the mine and sand causing a temperature difference to be thermally conducted to the surface of the soil. Results are presented for a wide variety of experimental arrangements. An attempt at simulating various minefield conditions was explored. Some of the surfaces examined above buried mine targets include smooth, moist, hand brushed, very uneven, and raked soil. Introducing clutter on the surface of the soil such as pebbles, rocks, leaves and wood has also been studied. Many of these parameters impeded the detection process. Thus, this method is not an allencompassing solution to mine detection but may improve IR methods in circumstances such as dark or cloudy weather. Outlined recommendations concerning future scientific studies into the proposed method may refine microwave enhanced IR imagery.
The history and development of the dental surveyor--Part III.
The dental surveyor is an indispensable instrument capable of performing a number of prosthodontic procedures. Surprisingly, the technique of surveying casts as part of the treatment planning procedure did not emerge until early in the twentieth century. This article reviews the origins and early use of the dental surveyor. It includes features common to all surveyors as well as the principal uses of these instruments.