Abstract: The present invention is a method and apparatus for isolating high frequency signals in a printed circuit board. A barrier strip (36) of staggered elongated grounding slots is positioned on the circuit board to prevent stray signals from leaking from one portion of the board to another. To further improve signal isolation, additional grounding holes (80) are placed around those areas where a trace on a circuit board makes the transition from one layer to another layer in a multilayer circuit board. In addition, microstrip filters (56, 58) are attached to the power or control traces of circuitry on the board at positions where the traces cross from one section of the board to another in order to filter out any stray rf signals that may be induced by the transmitter onto the power and control traces.