In one embodiment, the display 18 is connected to the waveguide 13 via the conductive component 3.

The dimensions of the waveguide 13 increases, corresponding to the increase in dimensions of the gap 10, when measured in a direction parallel with the connecting surface 6, from a first dimension D1 to a second dimension D2. The first dimension D1 is measured between the first wall 4 and the second wall 5 adjacent the connecting surface 6. The second dimension D2 is measured between the first wall 4 and the second surface 3b of the conductive component 3, at an end of the second surface 3b located farthest away from the connecting surface 6. The effective size of the waveguide 13, in other words, is increased beyond the first dimension D1, which, in one embodiment, is less than λ/20, as the waveguide 13 expands along the second surface 3 of the conductive component 3.

The first wall 4 of the waveguide 13 forms at least one conductor element 4a, the conductor element 4a extending adjacent at least one first recess 11, preferably between two first recesses 11. The conductor element 4a is tapered in a direction perpendicular to the connecting surface 6, in a direction towards the display 18. The height H of the conductor element 4a in the direction towards the display 18, shown in FIG. 4b, may be λ/2 or λ/4.