Follow along with the video below to see how to install our site as a web app on your home screen.
Note: This feature may not be available in some browsers.
Maybe there's a marvell or Atheros one... I can tell you there is not an Intel 3 x 3 AC adapter out there at all.
For reference, I checked the wifi card you posted and it's a PCIe half height card. That makes a difference as it's the older style and not the new m.2 formfactor. (You can tell the difference because the new one has 2 notches in it instead of 1)
This might be of help:
https://wikidevi.com/wiki/List_of_802.11ac_Hardware
With that list though, there is a full height PCIe adapter which is 3 x 3, but unless you have the room for it, it's not going to work.
WLE900VX 802.11ac / abgn 3x3 MIMO Atheros QCA9880 Wireless Mini PCIe 2.4/5 Ghz Dual Band
It doesn't appear there is a marvell at all, so it's been the same model Broadcom you're looking at, or the one Atheros model. The majority of the 3 x 3 devices I see listed used the Broadcom...
The 3 antenna design is pretty rare in any device. The more antennas used, the more complex the design, more power it consumes, etc. etc. As far as I know multiple spatial streams first only became a thing in 802.11n, so the entire setup is still fairly new. Even in draft it wasn't actually designed so that you would have 3 antennas on each side, and get 3 spatial streams. You might have 3 antennas on the AP and two on the client, and the 3rd antenna was really only there for diversity. After N was solidified a lot of the 3 antenna designed were dropped in favor of 2 x 2 instead. Once that gets engrained you get the chicken / egg problem. Vendors are happy with 2 antennas on their APs because the majority of consumer devices only have 1 or 2 antennas. There is no need to push for more antennas on the client side since most APs only utilize two antennas. Factor in the explosive growth of mobile and IoT, and you soon see that the market is dominated by this.
We are now seeing some crazy high antenna counts in consumer routers, but it wasn't necessarily because of wanting to push 4 x 4 to another device, but using MU-MIMO to support multiple smaller devices at the same time. I don't think there is a market at all on the desktop for 4 x 4 adapters, because anyone who's building a high end setup will just skip wifi and go straight to hardwired. There might be a slightly larger audience in the high end laptop market, but not so much that there is enough volume for someone to help push it forward. 2 antennas is usually enough to get the job done while you're mobile, and if you're doing heavy lifting it's usually near an outlet, so once again I'd be more inclined to just plug in if I really cared about speed.