ground plane on 2 layer board with wifi module
This is a 2014 post, but I just run into it. I cannot view the datasheet link for the wifi module, but I'm working on a design using BLE module (Silabs BGM111). On manufacturing datasheet, the layout recommendation should also apply to a wifi module. To answer the original questions, I don't think copper would block signal completely, but it will degrade the signal strength. Depending on your module antenna design, this copper/plastic clearance in 3D space can be different as well.