Question 1

Can you add an external antenna to this? If so, how?

Accepted Answer

Most definitely not. Where could you possibly attach one?

Question 2

Will this wireless card be recognized in a linux based OS?

Accepted Answer

Yes, works seamlessly under most linux setups.

Question 3

What is the true max speed  you got out of it ? (I understand that 150mbps is not realistic speed)

Accepted Answer

If your router is optimized to handle 150mbps and you have a connection of 150mbps then you are most likely getting 120mbps Max. My general rule of thumb is take off at least 20% of the speed shown. It looks like it uses the Realtek RTL8188CU  chipset so it should be decent.
But after reading the reviews they are saying it is pretty slow.
But you really cannot expect much more for something at that price point. 
If this is for a laptop I would recommend looking at changing your internal Wi-Fi card those will cost ~20-30 but you will get 30 times the performance.
The problem with small thumb drives Wi-Fi adapters is that the antenna is tiny. On a laptop there is a wire that goes around the screen to act as an antenna.
So unless this is for a desktop and you are near the AP then it's ok.
If this is for a laptop and you have G 54mbps looking to upgrade to 150 this will not improve the speed much maybe 20% boost but you will lose in range.
Internal WiFi cards are extremely easy to install.

Question 4

Can This go into injection/monitor mode?

Accepted Answer

I think he is talking about WIDI or MIRACAST.
This card is not compatible.
You need to look for a card that does Miracast or WIDI

In order to send video via Wi-Fi to a device you need a card that is compatible with WIDI, MIRACAST or others.

WIDI uses 802.11ad at 60 GHz making it have a speed of 7Gbps to Transmit Video to your component.
802.11ac uses 5 GHz and has a max speed of 1.3Gbps if your device can support that speed most are 867Mbps. 
So 802.11ad is 8 times faster than AC since it uses the 60GHz band.
The downside with using the 60 GHz band is that the range is very minimal.
That is why even new routers 802.11ac that go 867Mbps in the 5 GHz will still have a lower range than using 802.11 b, g, n in the 2.4Ghz range.

Lower Hz longer range but lower speed.
Higher Hz higher speed but shorter range.

Question 5

Hi: I have an older ibook which has an airplane card that doesn't work. I had OS 4.9? recently installed. Will this work with this older version of software? Thanks Lenny R

Accepted Answer

should work fine

Question 6

will this convert a printer to wireless?

Accepted Answer

No.  The printer will most likely not have built in drivers for this device.  Research your printer and find a supported wireless device or look for a wireless print server such as the BUFFALO N300 Wireless USB 2.0 Print Server.

Question 7

Does this product work with Blu ray DVD players with adapter port?

Accepted Answer

No, it will not.

Questions & Answers