Sistema de medida polivalente con configuración biestática para ensayos electromagnéticos

Abstract

The Radar Cross Section (RCS) is a parameter that, in radar technology, is utilized to characterize the reflectivity of a given object under the illumination of an electromagnetic wave. For decades, the understanding, analysis and control of this parameter has been of concern, mainly to the military, because a target with low RCS is more difficult to detect. This is why, along the years, test facilities for measuring RCS, with gradually better features and capabilities, have been developed. Due to the fact that most radar systems are monostatic, that is, both transmitter and receptor are situated in the same location, measurement systems have mainly focused on determining monostatic RCS. However, recently, bistatic radar systems (transmitter and receptor are separated) are attracting the attention of the scientific, academic and military communities, because they are able to detect sophisticated targets designed to make them less visible (ideally invisible) to the monostatic radar. In this sense, the interest in bistatic electromagnetic scattering and its measurement and characterization has also awakened. The requirements that need to be met for measuring the RCS of an object are not much different than those needed for measuring the typical parameters of a radiating element or an antenna. Besides, non-metallic parts are being more and more commonly employed in the fabrication of military platforms, and this encourages to study the electromagnetic behaviour of these materials. Thus, the electromagnetic characterization of materials (determination of their dielectric permittivity and magnetic permeability), the measurement of their energy-absorption capability or the analysis of their effect when they are utilized as covers, all conform an area of knowledge of increasing importance. This thesis is about an innovative and singular facility designed for electromagnetic tests. In this document, diverse applications and ideas for this facility are discussed, according to the needs that appeared during the research previously conducted by the Detectability and Electronic Warfare Laboratory (DEWLab) from INTA, the Spanish National Institute for Aerospace Technology. Among these ideas it is worth highlighting the interest in bistatic RCS and the investigation of new measurement techniques. And this is because this facility enables, indeed, the realization of bistatic measurements, which is probably the most relevant feature of this new system. But the rest of the applications were also considered and they influenced the final design because the facility was conceived as a multi-purpose system capable of measuring the radiation pattern of antennas, characterizing materials, measuring absorption or examining the behaviour of non-metallic materials in the presence of electromagnetic fields... Moreover, in the current economic scenario, a versatile system like this, that concentrates in a single facility several measurement capacities, becomes more relevant. In the thesis the design, fabrication and commissioning works (including the development of a control software) of the system are described, and the first bistatic RCS results obtained with this facility are shown. The measurements are compared with numerical predictions and the thesis presents an objective assessment based on an independent tool able to evaluate, both quantitatively and qualitatively, their similarity.