For range testing, I used my standard open-air method. I ran tests using the pair of adapters, since that's the way most people are going to use them, having paid over $200 for the privilege! I ran tests both in the default Up to 300Mbps (40 MHz bandwidth) and Up to 145Mbps (20 MHz bandwidth) modes, mainly for completeness. Since there are eight non-interfering channels allowed, there's no reason to not use the 40 MHz bandwidth default. For the tests, I used Channel 153, which has a bit more power than the lower channels (36, 40, 44, 48).
I'll start by showing the IxChariot summary of the 40 MHz bandwidth mode downlink tests. I was surprised to see essentially no throughput difference in test locations A-D, which range from in-room (A) to a point (D), where signal levels are definitely lower...at least for normal 11n products.
(You can click on the image to bring up a larger view in a pop-up window. Right click and open the link in a new window or tab if you want to be able to keep the image open.)
Figure 3: WNHDB3004 AP - Bridge throughput - Downlink - 40 MHz bandwidth mode
The more observant among you will notice that I got around 14 Mbps of throughput in my Location E dead zone, where only one other 5 GHz product has gone before (the D-Link DIR-665)! Unfortunately, throughput isn't as rock-solid as it is in the stronger signal locations. But I have to give NETGEAR props for this achievment!
But the victory glow faded quickly, because there was no joy in Location F, a mere 6 feet or so away from Location E. The additional sheetrock interposed by just that short distance just killed the signal dead.
Figure 4 shows the 40 MHz mode uplink test summary. Once again throughput in Locations A-D is basically the same. But with uplink Location E, throughput is higher and more stable in the first part of the run, then gets a bit wonky toward the end.
Figure 4: WNHDB3004 AP - Bridge throughput - Uplink - 40 MHz bandwidth mode
This behavior seems to indicate that Quantenna's technology works very well to keep throughput high and stable with strong to medium signal strength signals. But once signal strength drops below a certain point (and I don't know what that is), it can no longer maintain stable throughput, although it still manages to get a connection with decent throughput.
Figure 5 shows another downlink test summary, this time with the pair set to Up to 145Mbps (20 MHz bandwidth) mode. The interesting thing here is that you're not really sacrificing maximum throughput in the stronger signal locations. But you're getting much more stable and higher average throughput in Location D. Even for Quantenna's technology, it seems that you may be better off not being a bandwidth hog!
Figure 5: WNHDB3004 AP - Bridge throughput - Downlink - 20 MHz bandwidth mode
The last point of note is that you can see occasional throughput dropouts in both Figures 3 and 4. So it seems that Quantenna's technology isn't entirely dropout-free. But the dropouts are much more infrequent and much shorter than you get with standard 802.11n products (we'll look at this further, shortly).
The last test summary in Figure 6 shows 20 MHz mode, uplink performance. Results look very similar to the downlink plot in Figure 5.