Why is QMA backward compatible with QMA, but HPQN is not backward compatible with QN?
From a design perspective it would be an easy matter to make HPQN backward compatible with QN, however we chose not to. In the case of QMA, its basic structural parameters and electronic performance are very close to that of the original SMA connector, so we believed it was necessary to make QMA backward compatible with this design. On the other hand, we considered it unnecessary to make HPQN backward compatible with QN for two reasons: 1) The electronic performance of QN cannot compare with the original type N connector. 2) In the type N connector, the inner conductor is 3.04 mm and the internal diameter of the outer conductor is 7.00 mm. These dimensions have proved sound in all manner of applications for tens of years. The QN design, where the inner conductor is 2.97 mm and the internal diameter of the outer conductor is 6.85 mm, completely abandons these structural parameters resulting in a great deal of work in redesign, retesting and verification. We believe that to not make use
