Thank you for posting your question.
The Intel® Dual Band Wireless-AC 3160 is indeed 1x1. This means that the wireless adapter is currently reaching the maximum speed for 802.11n, also based on the router specifications. In order to reach a theoretical speed of 433 Mbps you will need a compatible 802.11ac router also capable of such speed.
You are correct. Your router and the other adapter are capable of 300mbps because they can use two streams at 802.11n speeds (150Mbps).
You would need to go to an 80211ac router as joe_intel indicated to get above 150Mbps speeds with the Intel® Dual Band Wireless-AC 3160.
The "Dual Band" part refers to the ability to use either the 2.4GHz or the 5GHz bands with this adapter.
You would need something different to utilize two streams (and two antennas)at the same time.
I had this same 150mbps speed issue with my AC-3160, however, it seems that it was a firmware issue on my Asus RT-AC68R router that was prioritizing negotiating 802.11n over the faster AC protocols.
FYI the frmware version 184.108.40.206.376_3626 released November 15, 2014 fixed the issue, and I am now seeing Win7x64 reporting 433 Mbps.
You should also note that 802.11ac only works on the 5GHz band, so it is useful to move all of your legacy devices onto the older 2.4GHz band that are still using 802.11n.
This is because routers will happily negotiate 802.11n over the 5GHz band and I don't see any popular router firmwares or adapter drivers with checkboxes for "Force 802.11ac" or "802.11ac Only".
It also helps to give a different SSID for each band so that you can tell for sure which one you're connecting to by its SSID (e.g. appending a "-5G" suffix). 802.11ac also uses 80MHz wide channels, but drops down to 802.11n and using 40MHz channels when an 802.11ac connection does not get established.
Thank you mike808; I also like keeping separate SSIDs for each band whenever possible.
It is not advised to use a wide channel in 2.4 GHz if there are many networks in this band but you can certainly change the adapter’s Preferred band to 5 GHz if using a single SSID for both bands or moving the desired wireless profile up in the profiles list.
I have a new Dell laptop with an Intel dual band wireless-ac 3160 network adapter. It is connected wirelessly to a Linksys E2500 wireless N router. I have cable internet access that supports speeds of 150 mbps. The top speed that I can get is 15 to 20 mbps with this network adapter. I have other laptops connected to this router that can easily get speeds close to 90 mbps. The other laptops all connect with 208.11N speeds. The New Dell laptop with the Intel adapter can only connect with 208.11A or 208.11G. It does not support 208.11N. I've tried all Intel recommendations and settings to no avail. Intel needs to solve this problem. The specifications for the ac-3160 adapter says it supports 208.11N, but in fact it does not. Many customers have waisted countless hours trying to improve the performance of this adapter to no avail. Intel needs to provide its customers with a real solution to this problem.