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I want to expand my PC's WiFi range, but the NIC delivers only 5 W. When I connect the antenna, not much more range is achieved. Is the antenna not the right one, or is the output of 5 W not enough? What should be my next step?

Desired distance: ~1 km

The antenna

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  • \$\begingroup\$ You seem to be answering your own question and, the only details you have provided give no indication as to whether your theory about the bottleneck is correct. Look at your question and try and read it from the point of view of someone else then, ask yourself if you see what I mean. On the other hand, in a more general sense, 5 watts should be more than plenty to get 1 km using a Yagi Uda antenna. \$\endgroup\$
    – Andy aka
    Nov 16, 2023 at 22:16
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    \$\begingroup\$ What’s the whole setup (on both sides)? Are the two antennas properly aligned? At 16 dBi you need them to be very precisely aligned. Are both antennas outdoors? Do you have line of sight? Is the Fresnel zone free of obstacles? What band do you use? And finally, what country are you in? In many places such a setup would be illegal as it would exceed allowed TX power limits. \$\endgroup\$
    – jcaron
    Nov 16, 2023 at 22:20

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The antenna doesn't care how much power you put into it, as long as it's not so much that it arcs or melts.

When working with decibels they add. So if your amplifier is 5 W, that's 37 dBm.

If you put that into an isotropic antenna (one that radiates equally well in all directions) you would get a certain range. Your antenna is rated to have 16 dB gain over an isotropic antenna because it focuses the power all in one direction.

Adding 16 dB to 37 dBm gives you 53 dBm which is 200 W, so with your antenna you should get the same range from 5 W that on isotropic antenna would get with 200 W. This is ignoring cable, propagation, and other losses, but for this question we're just looking at relative power so we can ignore those for now. If you were doing an actual coverage study you would need to take all gains and losses into account.

Because you're now concentrating the signal in one direction you need to make sure the antenna is pointed directly at the antenna you are trying to communicate with, otherwise the signal will basically miss its target. The higher the gain the higher the directivity, and the more accurately you'll need to aim the antenna. This is likely the problem you're seeing.

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