A 2.4Ghz Vertical Collinear Antenna for 802.11 Applications


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.

Equipment and Materials Needed

Components:

  • 2 meters LMR-400
  • 2 12" length of 5/16 K&S brass tubing
  • 1 12" length of 11/32 K&S brass tubing
  • 1 block of wood of at least (3.52ft) 1m long
  • 4 1" x 2" scrap wood blocks (or approximates)
  • 1 1/64th (2mm) thick piece of scrap metal
  • 1 brass toilet overflow tube ( EXACT DIMENSIONS NEEDED)
  • 1 US Quarter (or brass disk of equivalent measurements)
  • solder (non-acid core plumbing solder)
  • flux paste

Tools:

Required:

  • utility knife
  • hacksaw
  • High-wattage soldering gun (>260Watt)
  • metal ruler (Metric/English)
  • metal sandpaper
  • metal file (s)

Would make life MUCH easier:

  • hand-held pipe cutter
  • rotary coax cutter
  • vise (small)
  • micrometer (optional)
  • 'Dremel' tool with metal grinding/cutting heads or metal grinder
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