An electromagnetic interactive whiteboard system includes a first electronic pen (16) constructed and arranged to operate at a first frequency (F1). At least a second electronic pen (18) is constructed and arranged to operate at a second frequency (F2) that is different from the first frequency. An electromagnetic interactive whiteboard (12) has a single conductive grid (14) constructed and arranged to receive electromagnetic signals from the pens due to proximity of the pens to the grid. A circuit (30) separates the first and second frequencies into their respective X and Y component frequencies when the pens are operating simultaneously. A controller (20) receives a signal including the separated X and Y component frequencies of each of the first and second pens to detect each pen and to determine an X and Y coordinate position of each pen relative to the grid based on the X and Y component frequencies.