Abstract: A tunable microwave system includes at least two elements, each element being chosen from a propagating guide, an evanescent guide, a resonator, and at least one coupling device arranged between the two elements and configured to couple the two elements to each other, the coupling device having a holder having an aperture and having at least one elongate element the shape of which is elongate in a polarization direction contained in a plane of the aperture, the elongate element being securely fastened to the perimeter of the aperture at at least one end, the coupling device being configured to be rotatable about an axis substantially perpendicular to the plane of the aperture so as to modify a value of the polarization direction and so that the coupling between the two elements is dependent on the value of the polarization direction.