Uniform transmission lines are best suited for high-speed data transmission because of their broadband impedance characteristics. In some applications, a minor deviation from uniformity can help in optimizing other desired signal integrity metrics. This paper addresses some of the challenges involved with this approach.
Ask any engineer how to reduce the cross talk between two signal traces and the most common answer will be to add a guard trace. This should be the last resort, not the first choice. Guard traces can often introduce more problems than they solve. Find out why in this article.