Gain Gone Wild: How Too Much Antenna Gain Can Be A Bad Thing

March 24, 2016 at 8:00 AM

 

When designing a wireless network, one way to improve the strength and range of your Wi-Fi signal is to increase the antenna gain. This is a perfect solution for many applications.  But in certain situations, a high gain antenna stretches the wireless signal too far.

 

To put this into perspective, let’s look at an example of when too much gain becomes a bad thing:

 

You own a restaurant and want to set up a wireless network in an outdoor courtyard area. You choose an Omni-directional antenna to provide full 360° wireless coverage for your customers. For extra assurance that your Wi-Fi signal will reach everyone in the courtyard, you choose an antenna that also has a high gain rating of 15 dBi. Here is an illustration:

It seems logical that the high gain antenna would be able to connect the customers in your courtyard to your Wi-Fi network. But in actuality, your wireless signal is being projected far beyond the 300-foot coverage area that you’re aiming for. With the high gain antenna, the strongest Wi-Fi signal is outside of the courtyard space, leaving your patrons with slow speeds and poor signal quality. Weak vertical coverage from the high gain antenna also means the Wi-Fi signal won’t reach customers who are closer to the ground, sitting in chairs.

 

In this situation, your best option is an antenna with a lower gain, such as 5 dBi or 8 dBi.  This concentrates the Wi-Fi signal within a smaller area to better serve the customers within the courtyard. A lower gain antenna also has a stronger vertical reach to project the Wi-Fi signal lower to the ground for everyone seated. Here is a diagram:

The moral of the story is to proceed with caution when ramping up your Wi-Fi signal with a high gain antenna. It is possible to have too much of a good thing and ,depending on your wireless application, a high gain antenna might not be the best solution.

 

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