Avoid using the plated through holes, or vias As a signal passes through a via, a couple of properties change with respect to the impedance. First, the conductive doughnut surrounding the hole almost certainly comprises a different amount of copper than the width of the trace. The difference changes the impedance of the trace, because more capacitance is associated with more copper area. Second, the plated through hole lacks the continuous ground plane required to provide the constant impedance. Avoid 908 bends in traces by using chamfered or radius edges.
Sharp angles add parasitic effects to microstrip traces, resulting in minute impedance mismatches.
At high frequencies, additional charge accumulation causes an increase in capacitance at the corners of the trace bend and, therefore, a concentration of electric fields. Minimize the length of traces by using care in placing components. Avoid long runs, because they generate and pick up radiated noise from around the board. Such long runs are a common source of crosstalk. Avoid long parallel traces, unless they are differential, because they induce crosstalk.