Experimental Anechoic Chamber Measurements of a Target Near an Interface

Abstract

Abstract-The backscattered field of an illuminated sphere with diameter ∅ = 30.5 cm above a perfect conducting plate is measured in an anechoic chamber at different heights for a varying incidence angle φ in the range 5 • to 75 • . A high frequency field λ ∅ is transmitted, so that two significant transitions from lit to shadow regions are given over the entire incidence angle range for the considered ray field. The polarimetric behavior of the measured scattering matrix [S] is investigated by using the common coherent and incoherent decomposition theorems used by the radar polarimetry scientific community. Close to the shadow boundaries the polarimetric behavior of the sphere significantly changes. Representing the different decomposition parameters used in radar polarimetry over the incidence angle range, the transition zones are related to local maxima or minima. Hence, the extreme values of the polarimetric parameters give information about the geometrical parameters e.g target size and its height above the plate.

Analysis of Pyramid Em Wave Absorber by FDTD Method and Comparing With Capacitance and Homogenization Methods

“…There are different structures for EM wave absorbers, such as wedge [1], pyramid [2] and honeycomb [3] used in anechoic chambers for reflectivity measurements [4][5][6][7]. In this paper we obtain the reflection of pyramid absorbers over the frequency range of 100-1000 MHz.…”

Optimization an Anechoic Chamber With Ray-Tracing and Genetic Algorithms

“…Microwave anechoic chambers are currently in use for a variety of indoor antenna measurements, electromagnetic interface (EMI) measurements, and electromagnetic compatibility (EMC) measurements [2]. The mentioned chambers provide sufficient volume for an antenna to generate a known field.…”

Characterization of Antenna Interaction With Scatterers by Means of Equivalent Currents

“…A wellknown method is the so-called IsoFilter TM technique [1,5], based on spherical wave expansions, which allows the isolation of an individual radiation from multiple contributions that distort the measured radiation pattern. Another technique related to RCS measurements, based on the characterization of the contribution of two scatterers, is presented in [6].…”