Will an antenna with a high dbi be correct for your purposes?
When you buy an antenna, you will often look for it with the strongest signal. However, the local terrain and other factors in your surrounding area means that high gain is actually not the best choice.
In fact, the higher the gain, the more susceptible the antenna signal is to noise and other disturbances. So here is a guide to how the different radiation patterns look like and how different levels of profit will be.
It may therefore be important which way your antenna pointing, relative to your router, etc.
High Gain: 9 dBd = 11.1 dBi, 6 dBd = 8.1 dBi
High Gain antennas take all the input signal and sends them horizontal in a narrow beam.
This is a clear advantage in areas where the terrain is flat, provided that there are few trees or buildings in the signal path.
The narrow high gain signal will be blocked by hills, trees and buildings. So in mountainous country or around densely populated districts, is high gain no advantage to you. Signal Output will be frequent.
Gain medium: 4 dBd = 6.1 dBi, 3 dBd = 5.1 dBi
Medium gain antenna redistributes some of the signal that would have been sent vertically up and down, and sends out the horizontal. This implies that the signal will rise further, but will still be a relatively wide beam.
The signal is therefore less likely to be blocked by mountains or high buildings, making a medium gain antenna is the best choice for those in the suburbs and large villages.
Low Gain: 0 dBd = 2.1 dBi
Does the antenna pattern radiates in all directions like a round ball.
This broad signal is good around and over buildings, hills, valleys and trees. Therefore, a low gain antenna is actually the best choice for those who live in high-rise, urban areas or in bushy and hilly terrain.
Start to look at where your router is located. It it placed by other electrical products such as emit noise that degrade your wireless signal, or is it placed on the floor where the signal is not able to operate optimally.
If a router has to be able to function optinale circumstances you should place it up, ie. 50cm on a wall, for example. behind a door. Start by getting one to hold your router up in the air to check your signal, does is change when it is free of noise from other products, or just a little higher.