The coupling of the Lower Hybrid (LH) waves to the plasma is a critical issue which is still difficult to extrapolate from present tokamaks to the next generation. In particular the distance between the separatrix and the antenna front-end can be as large as ~0.15m on ITER whereas most of the present antennas operate with a 'gap' (i.e. separatrix-antenna distance) of 0.03-0.06m.