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To measure the complex dielectric constant of a material sample accurately by using the free-space reflection method using a monostatic horn antenna in the W-band, the authors of this paper have developed two processes to reduce errors and improve measurement accuracy. One of the improvement processes reduces errors caused by reflected millimeter-waves from surrounding objects. The process is carried out by averaging the reflection coefficients measured at multiple distances between the aperture of the antenna and the surface of the sample. The other improvement process reduces errors caused by the difference between the positions of the reference plane and the sample surface using numerical analysis. This paper presents overviews of our measurement setup for the complex dielectric constant and explains the two processes developed to reduce the measurement errors. The effectiveness of the developed processes is validated by measuring the complex dielectric constants of plastic plates. The result proves that the measurement errors can be reduced, and the complex dielectric constants of lossy plastic material can be measured accurately using the developed processes. [ABSTRACT FROM AUTHOR]

In this paper, a through-the-wall life detection system has been developed by using a broadband microwave technique. This system can not only determine and characterize human movement behind an obstacle but also determine the person’s position by employing the Fourier transform technique. The effectiveness of this system is shown by the experimental results where the presence of stationary and moving person behind an obstacle can be identified upto a distance of 17 and 30 m respectively. Since the movement of a human body is continuous, an averaged background subtraction technique has been developed which allows real time detection of human activities without requiring any prior knowledge of the environment, thus making the system suitable for practical applications. [ABSTRACT FROM AUTHOR]