Passive Microwave Imaging for Security Purposes

Abstract

Microwaves in the range of 1-300 GHz are used in many respects for remote sensing applications. Besides radar sensors particularly passive measurement methods are used for two dimensional imaging. The imaging of persons and critical infrastructures for security purposes is of increasing interest particularly for airline transportation services or public events with large crowds. For this reason public places have to be severely observed and protected. Therefore personnel inspection with respect to weapons and explosives becomes an important mean concerning terrorist attacks. Microwaves can penetrate clothing and a multitude of other materials and allow the detection of hidden objects by monitoring dielectric anomalies. Passive microwave remote sensing allows a daytime independent non-destructive observation and examination of the objects of interest under nearly all weather conditions without artificial exposure of persons or areas. The latter is an important item for the social and political acceptance of intensive observation. Problem orientated imaging and profiling systems have been developed using nearly the whole spectrum between 1 GHz and 100 GHz for a multitude of applications. The examples shown are laboratory results. The experimental systems are used to investigate basic key parameters for the specific applications like suitable frequency band, required spatial resolution, sensitivity, and field of view. Systems close to real-time are under investigation and development.