G06K 7/10168

Methods or arrangements for sensing record carriers, {e.g. for reading patterns} by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation {sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves methods and means used by the interrogation device for reliably powering the wireless record carriers using an electromagnetic interrogation field the powering being adversely affected by environmental influences, e.g. unwanted energy loss in the interrogation signal due to metallic or capacitive objects in the proximity of the interrogation device or in the proximity of the interrogated record carrier}