Helix antenna is the of the most powerful antenna for wireless signal. A 13 cm Helix wireless antenna can go up to 16DB of signal strength. The most important part is the coil. You will need to bend it with the same diameter so the signal can be receive evenly.

Video Simple design Of Helix Antenna

What do you need to have before you build 2.4 GHz Helix Wifi Antenna .

1 12.5 mm square aluminum tube, 70 cm long
1 1 mm thick aluminum disk, 12.5 cm diameter
1 Female, panel mount N-type connector
4 1.1 cm (7/16″) hot glue sticks
1 2.5 cm (1″) diam. all stainless steel hose clamp
6 1.25 cm (1/2″) #8 flat head stainless steel screws, lock washers and nuts
2 2,5 cm (1″) #10 round head stainless steel screws, lock washers and nuts
2 9 cm x 1.25 cm x 2 mm aluminum strips, bent at 5.5 cm from end
1 5 cm x 10 cm x 5 mm aluminum plate
1 2.5 cm x 2.5 cm x 2 mm aluminum shim that fits N-connector footprint
2.5 m #12 guage (AWG) copper wire
1 0.25 mm x 0.6 cm width copper strip arc-shaped to fit one quarter of a wire turn.

Source Antenne Hélicoïdale 2.4 GHz / 2.4 GHz Helix Antenna