25dBi Yagi Antenna worse than Alfa 7dBi panel antenna

[thxbest]

We got a cheap 2.4GHz 25 dBi Yagi Wireless WiFi Antenna on ebay to improve WiFi long range but after several tests indoor and outdoor, it turned out that the performance of the Yagi Antenna is much worse than
Alfa-APA-M04-directional-antenna-7-dBi.

The Alfa-APA-M04 is able to see around 10-12 APs and even connect to some of them. The Yagi dosen't even see half of them and also unable to connect.

I am wondering how is it possible that the 25dBi Yagi is so bad compared to the Alfa-APA-M04 7dBi?

Does anyone have experience with those antennas?

Thank you for any advice.

 

[adamwinn]

The design of Yagi antennas is very sensitive. If the ratios aren't correct then it's pretty much worthless. The panel style antennas tolerate less precise construction.

What was the seller's rating like? The 25DBi could be completely exaggerated?

 

[thxbest]

The design of Yagi antennas is very sensitive. If the ratios aren't correct then it's pretty much worthless. The panel style antennas tolerate less precise construction.

What was the seller's rating like? The 25DBi could be completely exaggerated?

This is the Yagi Antenna:

http://

Is it a fake Yagi Antenna?

 

[adamwinn]

Hard to tell by looking at it but the design does appear an odd design. I'm used to the branches being more differentiated in length.
Reach out to the seller?

 

[bill001g]

You find lots of suspect product shipped out of china. You never really know until you check out the company behind it. Most companies that make antenna have very detailed test documents on their site. They show diagrams of the signal pattern. When you do not find these it tends to make them suspect. These type of documents are required to get fcc and other approvals so the vast majority of legit companies have them.

You also have to be very careful about your testing. A yaggi is very narrow beam antenna and much more sensitive to polarization. You would have to be very sure that the smaller antenna was not getting the signal from a direction that yaggi is designed to reject signal from. If though you know where the end source is and you point both directly at it and you have the antenna oriented vertical/horizontal correctly you should always see more signal level on your yaggi.

 

[thxbest]

Hard to tell by looking at it but the design does appear an odd design. I'm used to the branches being more differentiated in length.
Reach out to the seller?

How can be determined that a Yagi Antenna is genuine or fake?

Do you have any links for more info?

 

[adamwinn]

Check out this link. It's a similar (if not the same) producto n Amazon. Some people give it 5 stars, others give it 1. Two issues:
1) Tight construction tolerances (manufacturer)
2) Have to aim them very carefully (user)

http://www.amazon.com/Brands-Wireless-2-4GHz-Antenna-Booster/dp/B0054MLMLA