Homebrew outdoor antenna to 2.4 GHz band.

Antenna gain is comparable to panel antennas including the Freedom Antenna Set sold in Finland. Comparing is made simple by connecting antennas to same computer with Orinoco WLAN card and indicating results in Link Test of the Client Manager. My antenna has been found about 2 dB better gain than the Freedom antenna, which is specified as 12 dBi antenna. And prices ... Oh, I need not even mention this! In Europe there is a maximum allowable output power of 20 dBm (100 mW) because of the ETSI standard we use. While Orinoco "red" card is transmitting 8 dBm signal and my antenna gain is about 14 dBi there has to be only 2 dB cable and connector loss to keep output level below 20 dBm. The Orinoco Adapter Cable takes about 1 dB and H1000 antenna cable takes 2 dB/10m. So using 5 metres antenna cable there is no risk of exceeding the output power within the ETSI standard. This antenna can also be built without the Ring to decrease antenna gain if needed especially with very short antenna cable.

Got no dough for a commercial WiFi antenna? Looking for an inexpensive way to increase the range of your wireless network? A tin can waveguide antenna, or Cantenna, may be just the ticket. This design can be built for under $5 U.S. and reuses a food, juice, or other tin can.

Introduction

The collinear antenna was historically used by base station sites, stacking various 1/2 wave dipole elements on top of each other for increased gain connected by some equipment to correct for phase error between the elements of the array. The higher in frequency the better in gain you can achieve in a relatively small assembly. The eight  element array built here will yield 6dBi gain in a radome of less than a meter.

There are 3 main sections to this antenna. Starting from bottom to top of the antenna, they are the RF connector/decoupler section, the elemental array section, and the quarter-wave whip section at the top of the unit.