When a manufacturer or a user desires to adjust a Braun tube, it is required to display a test pattern satisfying setting conditions of display modes on the Braun tube. The shell is provided with an inflow side pipe and an outflow side pipe for making a cooling medium flow inside. An arrangement cooperates with a portion of each of the first and second non-insulating strips in the tunneling region to form an electron tunneling structure exhibiting a tunneling region impedance. The characteristics are determined from the displacement current and the change in optical density. The second module is configured to adjust a bandwidth of the wireless communication device based on the operating environment as determined by the first module.