Simple Way To Increase The Power of Your Antenna
If you live in a country where this is acceptable, such as Belize, you can increase the power of your antenna by simply changing the country code within your wireless config.
To do check the current power of your adapter, run
iwconfig (adapter)
Where you change (adapter) for the actual adapter you have. Ex:
iwconfig wlan2
Look for the line that shows Tx-Power= and note what your dBm is running at. This will give you a baseline for your existing setup.
Then to change it and increase the power, type in the following to change it to your country code if you are in Belize (which allows this)
iw reg set BZ
iwconfig wlan2 txpower 40
You can then run the following command and see how your Tx-Power has changed
iwconfig wlan2