I'm designing a capacitive sensor which uses an active shield to focus the sensing field. This much works well.
Now, in order to most effectively protect the active signal from noise I'd like the shield to be a copper pour on both sides of my PCB, in the region of the trace carrying the active signal (the trace is ~200mm long, and the width of the pour would be ~90mm width). The excitation frequency is currently 25kHz, though this may be revised up to 16MHz.
Does increasing the area of the copper pour make it more difficult to drive the voltage of the shield?
The schematic below shows top copper in light yellow, bottom copper in dark yellow. To consider the worst case, I'd like to pour the entire 90x300mm area for the shield.