Crosstalk Reduction Using Defective Ground Plane Structures In RF Printed Circuit Boards

A new crosstalk reduction technique is proposed, which utilizes defective ground plane structures. With some basic defective ground plane structures, near end crosstalk (NEXT) and far end crosstalk (FEXT) of the coupled lines are reduced, without significant change in signal transmission property. As per the 3X thumb rule, the spacing between two traces must be three times that of the trace width, in order to avoid crosstalk. Without using additional Printed Circuit Board components in the design, a new method is proposed to reduce the crosstalk with the spacing of 0.5 mm and the line width chosen for 50 Ω characteristic impedance. The method proposed has been validated by fabrication and measurements. Both time domain and frequency domain responses are analyzed. Due to the narrow band property of these defective ground structures, the usable bandwidth is narrow. In order to achieve wide usable bandwidth, multiple defective ground structures are used.