A multiple-layer circuit board has a signaling layer, an exterior layer, and a ground layer. A pair of differential signal lines implemented as strip lines are within the signaling layer, and propagate electromagnetic interference (EMI) along the signaling layer. An element conductively extends inwards from the exterior layer, and as an antenna radiates the EMI propagated by the strip lines along the signaling layer outwards from the circuit board. A defected ground structure within the ground layer has a size, shape, and a location in relation to the element to suppress the EMI propagated by the strip lines to minimize the EMI that the element radiates outwards as the antenna.