Unlike some models, the Asus USB-AC56 uses external high-gain antennae. This should improve performance, especially if combined with the two additional internal antennae listed in the specification.
While this is a very small package into which to cram so many antennae it may provide a boost in speed using wireless diversity and beam-forming technology. The unit itself feels to be of high-quality and the plastics do not creak or rattle as they do on some cheaper models.
It is also worth noting that the antenna is connected by a standard screw connection so if you wanted additional signal gain you may be able to add a flat directional or a long 9dB antenna. The side of the device has a small recessed wps button on it.
The main potential advantage of upgrading with an 802.11ac adaptor is the ability to maintain better speeds at longer range. We created three test scenarios. Firstly with the adaptor connected to a laptop and placed at a distance of 1m to an 11ac TP-Link router. For the second scenario the laptop was taken outside 10m from the building while the router remained on the fifth floor in a window for a total distance of 18m. In the third scenario the laptop was taken 80m from the building (total 82m).
The laptop’s integrated 802. 11n adaptor returned a throughput of 184 Mb/s while the AC56 achieved 209 Mb/s. This is the highest data rate for an 802.11ac USB adaptor we’ve tested even if it’s only a 10 percent improvement in maximal throughput over best-case 802.11n with a 3x3 MIMO antenna setup.
At 18m the 802.11n laptop dropped to 67 Mb/s while the AC56 maintained 201 Mb/s. There was a similar story in the extreme range test. The 802.11n adaptor dropped to a speed of 86 Mb/s while the AC56 maintained a throughput of 142 Mb/s.
One of the most remarkable things about the testing of this and the other wireless AC units we tested was that you could see the new adaptive signal technologies working.
For the first minute of connection the data rate remained at a tiny 8 Mb/s and before jumping to the maximum speed and staying there.
Note: the Asus USB-AC56 was tested here on a laptop that only offered USB 2.0 ports. This severely restricted the unit's true performance potential.
For a full technical review of the USB-AC56, measured with 802.11ac and 11n networks, check the Macworld UK review.