Radiometry system with an aperture synthesis type antenna and its application to hyper-frequency imaging

Abstract

A radiometry system including an aperture synthesis antenna array type, including plural antenna elements, distributed in an antenna plane relative to at least one axis, according to a determined law. Each antenna element includes first and second coupling probes sensitive to hyper-frequency electromagnetic signals with dual linear polarization in quadrature (arbitrarily referred to as horizontal and vertical polarizations). The probes are connected two by two with electric receiving circuits to create a synthetic aperture. The horizontal (f,-f,) and vertical (f,-f,) coupling probes of successive antenna elements (e,-e,) are oriented in the antenna plane (At′), along each of the axes (&Dgr;), such that at least one of the horizontal or vertical probes (f,-f,, f,-f,) presents a 180° phase shift from one antenna element to the other (e,-e,), with the phase shift obtained by a sequential 90° rotation of those probes (f,-f,, f,-f,). Further, 180° phase shifts (&PHgr;,, &PHgr;,, &PHgr;,, &PHgr;,) are applied onto the outputs of the horizontal (f,-f,) and vertical (f,-f,) coupling probes, when one of the orientations of an antenna element (e,) is taken as the phase origin reference, in order to compensate for the 180° phase shifts with respect to the corresponding coupling probes (f,-f,) of the reference antenna element (e,).