Coupling between circuitry on printed circuit boards can be mitigated by a variety of well-known techniques. One such technique is to isolate circuitry in different areas of the printed circuit board by strategically placing a gap in the signal return plane. However, this technique is only effective at reducing common-impedance coupling, which is generally not a significant coupling mechanism at frequencies above 1 MHz. This paper investigates the effect of a gap located between and parallel to adjacent microstrip traces. The effect of the gap on the mutual inductance and mutual capacitance is evaluated. Laboratory measurements and numerical simulations show that gaps in the return plane are ineffective at reducing inductive and capacitive crosstalk in most configurations, and in some cases they increase the mutual coupling between printed circuit board traces.


Electrical and Computer Engineering

Keywords and Phrases

Analog; Capacitance; Capacitive Crosstalk; Common-Impedance; Common-Impedance Coupling; Coupling; Digital; Electromagnetic Compatibility; Electromagnetic Coupling; Gapped; Ground Islands; Ground Plane; Inductance; Inductive Crosstalk; Isolation; Microstrip Traces; Moating; Mutual Capacitance; Mutual Inductance; Printed Circuit Board; Printed Circuit Boards; Printed Circuits; Signal Return Plane

International Standard Serial Number (ISSN)


Document Type

Article - Journal

Document Version

Final Version

File Type





© 2005 Institute of Electrical and Electronics Engineers (IEEE), All rights reserved.

Publication Date

01 Jan 2005