The chamfering of 90 degree routing corners is a technique used to reduce reflections caused by the corner in a microwave frequency route. Arcs can be used, but should have a radius of at least 3x the route width. Chamfering (also called mitering) is an alternative, where the outer point of the corner is sliced off, as shown in the images below. Because Altium Designer's track objects have rounded ends, they cannot be used to create a chamfered corner. To create the chamfered corner the selected track segments are replaced with region objects.

Chamfering Routing Corners

To chamfer the corners in a route:

1. Select the track segments to be chamfered.
2. Select the Tools » Convert » Convert Selected Tracks to Chamfered Path command.
3. The Convert Selected Tracks to Chamfered Path dialog will open, enter the required chamfer amount. Note that both the outer and inner edges of the corner can be chamfered.
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   The percentage mitre is the cut-away fraction of the diagonal between the inner and outer corners of the un-mitred bend.

Only those track segments that are part of 90 degree corners are replaced with regions to create the chamfers, giving the results shown above.

How Big Should the Chamfer be?

The percentage mitre is the cut-away fraction of the diagonal between the inner and outer corners of the un-mitred bend. 

The optimum mitre for a wide range of microstrip geometries has been determined experimentally by Douville and James. They find that a good fit for the optimum percentage mitre is given by

Subject to  and with the substrate dielectric constant .

This formula is entirely independent of . The actual range of parameters for which Douville and James present evidence is  and . They report a VSWR of better than 1.1 (i.e., a return better than −26 dB) for any percentage mitre within 4% (of the original ) of that given by the formula. At the minimum  of 0.25, the percentage mitre is 98.4%, so that the strip is very nearly cut through.