The present invention relates to a filtering circuit comprising at least two slot line resonators (R1, R2) arranged side by side and realised on a dielectric substrate having a first face equipped with a conductive layer and a second parallel face, each of said at least two resonators comprising a slot line (3) etched in the conductive layer and folded according to a spiral pattern counting a plurality of turns, with a shape factor such that the slot line has parts noticeably parallel or concentric. According to embodiments of the invention, at least one turn of the spiral pattern of each of the resonators comprises at least one discontinuity (10), the discontinuities of said at least two slot line resonators being arranged in such a manner as to increase the electromagnetic coupling between said at least two slot line resonators.