A passive antenna system for data acquisition in scattering applications

Abstract

This letter describes a passive antenna system based on the modulated scattering technique (MST) implemented in the bistatic configuration. The system uses an array of passive dipoles driven by optical fibers. The array can move and rotate around a square test area and it is possible to measure field-scattered data by cylindrical targets placed inside the test area. Some preliminary experimental results are presented and compared with analytical data. The measurements are in good agreement with theoretical values.

Measurement of the modulated scattering microwave fields using dual-phase lock-in amplifier

“…In the conventional system, the received signal is approximately given by [6] (1) where is the amplitude of the scattered signal from the dipole scatterer, is the amplitude of the bypassed unmodulated signal, and are each angular frequency of the signal source and the modulation source, respectively. is the phase of the unmodulated received signal and is the phase of the modulated scattering signal.…”

“…The modulated component includes the amplitude and phase information that characterizes microwave fields at the probe's location. Thus, the modulated scattering technique allows us to measure the amplitude and phase of microwave fields with the minimum perturbation [3]- [6]. This letter begins with comparing with the conventional system for measurements of the modulated scattering microwave fields.…”

Detection of PEC elliptic cylinders by a memetic algorithm using real data

“…Since the MST is used [8,9], the measures are finally obtained by an aperture antenna (120°beneath in the azimuth plane). The illumination/measurement prototype, which is arranged in a shielded semi-anechoic chamber, is described in detail in [7]. …”

“…First of all, the above inversion method, developed in [4] for dielectric materials, is extended here to the case of perfect electric conducting (PEC) cylinders. Moreover, the new version of the approach is validated for the first time by using real scattering data measured in an anechoic chamber via a prototype of an imaging system [7], which is based on the modulated scattering technique (MST) [8].…”

“…The slots in the ground plane may have either a circular shape [4 -8] or a sinusoidal or a triangular profile [7]. The operational characteristics of the filters are controlled by the size and the distance of the ground slots [4 -8]; in this case, their pattern is uniform.…”