I bought these antennas for my Mofi 4500 Wifi router, installed in my travel trailer, when used for long-range Wifi as WAN. The trailer positioned about 50 feet from the router, and the signal goes through 4 walls.
With the two original 5dBi onmi-directional whip antennas, I got a signal of 44% to 50%. The signal was so degraded, that the wifi signal was mostly useless, taking 30 seconds to show a google search result, and dropping and re-connecting regularly. Then, I installed these two 9dBi directional panel antennas, I got a signal of 91%, and a steady signal and web page results showing instantly. You can say, the difference is like night-and-day.
Before buying I read-up on wifi antennas, the various types of antennas, how they work and how they perform. I learned that the dBi number refers to 'gain' and the more gain the better the signal, but it's not increasing the signal level as much as it is concentrating it in a particular direction. A small 3dBi antenna sends the signal out in all directions, up down, forward backward, left and right. It doesn't matter how you position it, as it radiates in all directions. A longer 7dBi or 12dBi whip antenna, when positioned vertically, narrows the beam to the horizontal plane, and doesn't send any signal up and down.
Then a "panel" antenna is designed to send the signal in the direction the panel faces, with a fairly narrow conical pattern, about 30 to 60 degrees wide. This type of antenna is ideal for me, because I am trying to get wifi signal from a single AP in a particular direction. I simply aim both panels at the AP. This has the *added benefit* of rejecting interference.
Interference is a bigger problem than most people know, as the 2.4GHz spectrum is becoming more and more crowded with Wifi, Bluetooth, cordless phones, microwave ovens, and garage door openers in cars and homes. That's why I found a LOT of variability in my wifi throughput. During the day, it had poor throughput, and was constantly dropping but in the evening it was fast and solid. In both cases, signal was the same 44%-50% and nothing changed or moved - so what caused this variation? Interference. When more people are using the 2.4GHz spectrum, throughput is very poor, but when other people stop using it, the throughput is suddenly better.
When I scan for Wifi, I see about 20 access points in homes around me. That is potentially a lot of interference from other networks. But with a directional antenna, it concentrates power in the direction I want, and rejects everything else. Thus the directional antenna is the KEY to wifi performance.
These antennas from Alfa Networks are good quality. Alfa is a decent Taiwanese company that makes quality radio equipment. I have no doubt that this antenna is properly designed and built, and works as specified. The outside of the box clearly shows the response pattern for this antenna, and I am sure it performs exactly as described. It certainly worked for me.
Now as to those reviewers who said this antenna "doesn't work" I think they don't understand about how to properly make use of an antenna like this. Maybe they didn't know that a whip antenna is somewhat directional, and this panel is even more directional, and in either case, the antenna must be properly aimed.
For this panel, the 'alfa' logo is the 'front' of the panel and must be aimed at the target, but if the logo faces away, then you get no signal. I wish this was clearly explained on the box, so that non-technical users can get good results. But the fact is, that most antenna products don't explain this, which is why so many people get such variable results.
One other issue with this panel - it only rotates 180-degrees. So there are some directions it cannot face. But you can get around it by rotating the screw mount to get the other 180-degrees of movement. Weird, but it's workable.
I noticed that most users buy this antenna for flying drones. It is excellent for that application! But you must aim the panel at your drone. While a whip antenna must be pointed perpendicular to the drone, the panel must aim the face of the panel towards the drone. Then, the whip will work well, but this panel will work even better.
Now you can easily see why this antenna is probably not suitable for your home wifi router. To cover all areas of the house, you need an onmi-directional antenna, and the one that came in the box is probably the best choice. But if the AP and client are both fixed, (as in my situation) or the equipment is always aimed towards the target (as with a drone) then it makes sense to use a high-gain directional antenna, like this alfa panel.
Good luck - with the mysterious world of antennas, you're going to need it.
