This article is about trace bends on PCBs and its potential impact on near fields and EMC. Considering the complexity of the PCBs of today, it is impossible to have a trace without a bend on it and continuing with this trend we will have to use bends more often than before. Hence in this article, I have tried explaining the effect of a bend on near fields and I have considered bends with various angles and have formed a relationship between the variations of the associated near fields with respect to the variation of the bends.

There is a fair amount of data available in the electronics world that says PCB traces with 90 degree corners (bends) do a lot of harm and I think an equal number of theories that counter argue this theory and say that they are perfectly harmless. One particular article that impressed me was from Mr. Douglas Brookes ? 90 Degree Corners: The Final Turn (1). In that he had constructed PCBs with various trace bends on a microstrip configuration and then performed two logical experiments ? one to measure the impedance discontinuity on the traces with and without bends and the other to measure Emissions from the traces at a distance of 1 metre. The reason behind measuring the impedance discontinuity is that, at bends the traces have a slightly different dimension (see figure 1 below) which mean the impedance at that point will be different (This can be measured using TDR method). After an extensive study, the conclusion was that the bends do not make any difference on both of the observed phenomena i.e. Impedance discontinuity and Emissions and hence having a bend on the PCBs is decisively harmless.

Continue reading the complete article here: