Abstract: An apparatus for a pen-based input system, such as personal communication device or notepad computer, which shields against RFI/EMI fields causing problems either in the internal electronics or in the environment surrounding the system. A digitizer used in such a system must be able to sense a location of a special pen used for inputting information. This digitizer is also a source of RFI/EMI fields. A shield of such RFI/EMI fields must allow the digitizer to work and reduce the amount of RFI/EMI released to the environment. A special transparent conductive layer, such as a coating of Indium-Tin-Oxide, beneath the pen input protective plate performs these two necessary functions. The conductive layer also shields the system internal electronics from external RFI/EMI sources such as attached cellular telephone systems or radio LAN systems.