Cantenna

A homemade device to increase WiFi signal

Materials:

1 circular pizza tray (32 cm diameter)

1 Tin can lid (9 cm diameter)

Electrical tape

Specifications:

cantenna diameter: ~90 mm

cantenna length: ~300 mm

WiFi adapter antenna distance from closed end: ~30 mm

Other equipment:

USB WiFi adapter with antenna (2.4 GHZ)

(pictured but not required) powered USB hub

USB extension cable

The pizza tray is a circle with diameter of about 32 cm. When rolled up into a cylindrical tube, the maximum tube diameter is 10.2 cm. The max tube length at furthest points equals the tray diameter of 32 cm. Roll the tray to about 9 cm diameter so there is some overlap in the center.

The tin can lid acts as a reflector on the closed end of the tube. Place this about 2 cm from the furthest edge of the tube to reduce the effective tube length.

Any reflective material can be used as an closed end reflector. A tin can lid, a mirror, or even clear plastic!

Adjusting the position of the end reflector also in theory tunes the frequency to different WiFi channels by increasing the signal at different frequencies within the 2.4 GHZ band range.

The ideal tube length for a 9 cm diameter cantenna is calculated to be 15.4 cm (see ref) but since our tube is much longer, it is acceptable to use twice the calculated length at about 30 cm. This will capture twice the volume of WiFi packets per cycle, narrow the aperture angle and increase the signal.

References:

Cantenna dimensions calculator: https://www.changpuak.ch/electronics/cantenna.php

WiFi Channel frequncies: https://en.wikipedia.org/wiki/List_of_WLAN_channels#2.4_GHz_(802.11b/g/n/ax)