SLOTTED WAVEGUIDE ANTENNA FOR NEAR-FIELD FOCALIZATION OF ELECTROMAGNETIC RADIATION

A radial slot antenna (1; 60) comprising a radial waveguide, which includes an upper plate (5), having a centroid (O) and an edge region (14) and provided with a plurality of radiating apertures (4), formed as slots in the upper plate (5), which develop according to an ideal annular pattern (16) around the centroid (O). The radiating apertures (4) are arranged in such a way as to form at least one first radiating region (31a) and one second radiating region (31b), which are distinct and radially separated by a dwell region (33a) without radiating apertures and wherein, in the first and second radiating regions (31a, 31b), radially adjacent radiating apertures (4) are separated from one another by a respective mutual radial distance, the dwell region (33a) having a radial width (delta) greater than the mutual radial distances of the radiating apertures (4) in the first and second radiating regions (31a, 31b). The slot antenna further comprises a signal feeder (10) operable for supplying am electromagnetic field (Psi0, Psi1) so as to assume, in the first and second radiating regions, opposite phases, in such a way that the electromagnetic field emitted by the slot antenna can be expressed via Bessel functions.