The installation of beryllium (Be) Faraday screens (FS) at the ICRF antennas in JET resulted in elimination of the RF specific effects on the plasma boundary by the impurity influx originating at the screens. In dipole phasing, k|| = 7m­1, the influx is for all purposes negligible. In monopole (k|| = 0m­1) the beryllium influx does not exceed fFS = 1 x 1019 atoms MW­1 s­1 and corresponding dZeff/PRF < 0.005 MW­1 . The observed dependencies of the fFS (in antenna voltage, antenna phasing and the angle between FS elements and the magnetic field in the boundary B(a) = Bq (a) + BT(a) confirm that the release mechanism is the sputtering by the ions accelerated in the RF­enhanced Bohm-Debye sheaths forming at the front face of the FS. When the angle between FS and the B(a) is 22 degrees the fraction of the RF power radiated by the antenna, dissipated at the screen, can reach 40%. At high antenna voltage the arcing across the FS can occur. With dipole phasing the heating efficiency is not degraded even with the large angle and all the power coupled by the antenna is absorbed at the resonance position near the plasma centre. The open screen design did not introduce any disadvantages. The experience from the JET operation at powers up to 22MW shows that, if the necessary conditions are met, i.e., RF rectification is minimised and material with the low sputtering coefficients at energies 0.5-1keV is used, then the influx from the FS is eliminated.