Validation of a 3D bistatic microwave scattering measurement setup

Abstract

[1] We present a 3D spherical bistatic experimental setup developed in the anechoic chamber of Institut Fresnel in Marseille, France, for scattering measurements of targets in the microwave domain, both in copolarization and cross-polarization. We first describe the geometry of the setup, the measurement protocol, and the calibration process. The results obtained for different metallic and dielectric targets are then compared to numerical simulations, computed either using the coupled dipole method or Mie theory. These comparisons are used to validate the algorithms and the setup, as well as to provide information on the accuracy of the measurements.Citation: Eyraud, C., J.-M. Geffrin, P. Sabouroux, P. C. Chaumet, H. Tortel, H. Giovannini, and A. Litman (2008), Validation of a 3D bistatic microwave scattering measurement setup, Radio Sci., 43, RS4018,

On the Calibration of a Multistatic Scattering Matrix Measured by a Fixed Circular Array of Antennas

“…This introduces signal variations when the same antenna is used in an emission mode or in a reception mode. Secondly, it enables to perform not only qualitative but also quantitative measurements [17]. Thirdly, it enables to detect the antennas which are not properly working during the acquisition time.…”

“…Different calibration processes have been proposed, enabling full polarization corrections by means of distortion polarization matrices [20][21][22]. In other cases, a single complex coefficient turns out to be sufficient to perform an efficient calibration [17,18], this coefficient depending only on the frequency, on the emitter's position and on the amplitude of the measured fields. Due to the time spent in the mechanical movements, this coefficient can also be corrected for drift phenomena [23].…”

“…When the targets become more complex and in particular when they have a full three-dimensional structure, the calibration on the incident field is not fully satisfactory. In that case, another procedure is directly applied to the scattered field with the use of a reference target [17][18][19]. This is coupled with the fact that the incident field cannot be measured and/or computed with a sufficiently high precision to perform a stable calibration procedure.…”

“…Moreover, this two-port calibration technique is not sufficient to take care of the antennas diversity and the scattering phenomena. Following [17], we prefer to exhibit a single complex coefficient for each pair of emitter/receiver antennas, assuming that the antennas are all emitting/receiving with the same polarization. This produces a calibration matrix which enables to take into account the various antennas behaviors which can also differ from the emission mode to the reception mode.…”

A Rigorous Forest Scattering Model Validation Through Comparison With Indoor Bistatic Scattering Measurements

“…Some experiments have been performed by using two antennas on separate platforms [12][13][14][15][16] while others are carried out with a monostatic radar and a reflective plane [17]. Within this framework, ONERA has performed scaled-model measurements in its anechoic facility BABI.…”