Built your own Helical wifi antenna.
There is many type of antenna external for used in wifi, grid antenna is which most commonly used for the wifi link long distance.
but the price of grid antenna is very costly.
alternatively, you can make your own wifi antenna with quality and low cost, the antenna that suitable is helical antenna.
The idea behind this aerial was for anyone to be able to make their own aerial for point to point links, and do it cheaply. The criteria are cost effectiveness, ease of construction and durability. Durability is important as you don’t want wind, beak cleaning magpies and highly destructive nibbling cockatoos ruining your Quake III and Unreal Tournament sessions.
Birds landing on the aerial have the effect of severely diminishing the signal, too.
Helical antenna can be made with materials which is easy to be found and of course its cheap price.
we can easily get high gain by using helical antenna, the more number of turns is mean the more gain you have.
The gain you will require for each individual WiFi antenna system will dependant on any direct objects in your path, the distance you must cover and the individual wifi cards.
These all must be taken into consideration before choosing the proper antenna system.
Helical antenna is suitable for Point-to-Point systems.
Point-to-Point systems usually involve 2 different wireless points, or building to building wireless connections.
But there are exceptions to every rule. If the access point is across a long valley and the owner of the system wishes to share the connection with multiple users on the other side of the valley.
This would be a point to Multi-Point system but using directional antennas.
for more reference and detail about Helical antenna for wifi, you can visit this page:
(you must adapted the antenna for suitable working in wifi, the most used wifi in the world work in 2.4 GHz)