If the antenna coupler and shielding cover are closed, a standing wave may be generated between the floor of the coupler and the ceiling of the shielding cover. To reduce this effect, the ceiling of the shielding cover is lined with a foam material to attenuate the magnetic field, which is at its maximum at the metal surface. In addition, the electric field component is attenuated by a pyramid-shaped absorber. The shielding cover upgrades the antenna coupler to a high-grade RF shielded chamber that prevents interference radiated by base stations or other neighboring test and service sets from affecting the measurement results of the DUT. This is particularly important in BER measurements. The closing mechanism can easily be operated with only one hand and ensures very high shielding effectiveness of >50 dB by producing a defined contact pressure.