Why my Wi-Fi performance is not improved after changing antennas？

Why my Wi-Fi performance is not improved with new high gain antennas

Changing high gain antennas for our router/AP might be a way to extend our Wi-Fi signal further, but it’s not feasible in all circumstances. Explanations below will help you to make clear why your Wi-Fi performance is not better or even worse when you change the original antennas to new antennas with higher gain.

1. Antenna gain is not the only factor which will affect our router/AP’s Wi-Fi performance. We have also taken many other factors such as VSWR, impedance matching and even the distance between each antenna into consideration during our design. All these factors will also affect the Wi-Fi performance. We can make sure that our original antenna is good to cooperate with the router/AP, while for a new antenna, it’s hard for us to tell how well it will perform.

2. Omni-directional antennas with high gain concentrates more power to horizontal in the sacrifice of vertical power. Therefore, the signal range in horizontal can be improved, while in vertical it will be worse. (refer to FAQ-468)

3. A high gain antenna can extend the Wi-Fi signal range through straightaway transmission, it’s much helpful in outdoor environment with few barriers. While indoor environment is more complicated that we not only get router/AP’s signal through straightaway transmission, but also through reflection, refraction and diffraction. So in some indoor environment, just changing a high gain antenna is not helpful to improve Wi-Fi signal.

Why can’t I deploy different external antennas to cover different places?

If we deploy different external antennas to a router/AP, for example, wired one antenna to second floor (see below) or change one to a high gain directional antenna, it will be able to extend your Wi-Fi range theoretically, while in real environment, it’s infeasible since it will introduce some other problems which will affect the wireless communication a lot.

1. Refer to the deployment below, if we wired one antenna to the 2^nd floor, it will introduce a hidden node problem. Both client 1 and client 2 can talk to the wireless router, while they are unable to see each other, which means they won’t restrain each other for talking. Then if client 1 and client 2 talk to the router at the same time, the router will failed to distinguish these messages and required a retransmission. This will reduce the router’s efficiency a lot.

2. This deployment will introduce 2^nd floor’s wireless interference to the router on 1^st floor. For example, if your antenna on the 2^nd floor has detected a wireless interference in the same frequency as the router uses, the router will stop talking even with the devices on the 1^st floor, this will also reduce the router’s efficiency.

Why can’t I just use one antenna on the router/AP which has more than one antenna?

Our router/AP which has more than one antenna can negotiate to 2x2 or 3x3 MIMO with other devices, this means they can transmit their data with more than one stream through different antennas. If we just use one antenna on these router/AP, it may decrease the wireless performance a lot.

Besides, some models of our products are designed with main antenna and vice antenna. The vice antenna can barely work without the main antenna, that is to say, these products without main antenna is nearly not working at all.

Summary

If you want to change the external antennas on your router/AP to meet your special Wi-Fi requirements, we recommend you to replace all of them with same antennas other than use only one or different antennas in one router/AP. While since router/AP’s Wi-Fi signal and performance is affected by many factors, we can’t make any promise which antenna is better just based on the difference of antenna gain.