Image Number 12 for United States Patent #6150895.
A circuit board having a transition region at its perimeter. The transition region provides a deliberate increase in impedance between the voltage and ground plane from the interior side of the transition region where the board impedance is approximately that of the board impedance at an interior region of the circuit board to the edge side of the transition region where the impedance level approximates or is slightly less than that of surrounding air. In one example, the voltage plane in the transition region has a geometric configuration that provides a decrease in plane material (such as a hole, stripe, or triangle pattern) from the interior side to the edge side of the transition region. With other examples, the distance between the voltage and ground plane increases from the interior side to the edge side of the transition region.
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