Linear Focus Parabolic Wifi Antenna

Simple Construction - Great Wifi Network Range Extender.

Parabolic wifi antennas are generally thought of as dish shaped objects, fed by a yagi, biquad or helical radiator at the focal point. These dishes are curved in three dimensions and involve considrable effort to construct from scratch. An alternative is the two dimensional "linear focus" reflector. It focuses energy along a "focal line" instead of one point, and works quite well with simple dipole antennas. Design is as simple as selecting a suitable parabolic curve, plotting it on a flat surface, and fitting a sheet of mesh or solid metal to the parabola.

Doing the design calculations by hand is quite time consuming; there is excellent software enabling one to create a template and in minutes. For doing the calculations, one good parabolic antenna calculator is HDL_ANT. Another very useful calculator, called Parabola, was designed originally for solar cooking, and can be used for making wifi network antennas. When using these, bear in mind that the f/D ratio (focal length /diameter) should be between 0.3 and 0.6 for optimal performance.

This linear focus parabolic wifi antenna consists of a sheet of metal shaped to precisely fit a two dimensional parabolic curve. Gain is about 15 dB over a dipole, and depends greatly on quality of construction. Of greatest importance is shaping the sheet metal to accurately follow the parabolic curve given in the template. Parts may be found at large hardware retailers such as "Home Depot" or local scrap metal dealers. Versions of this antenna have been made using automotive sheet metal; others use wire mesh. Whatever the material: follow the curve!

Parts & Equipment Required:

1. one 36" x 2" aluminum flat (to be referenced as flat "A")
2. one 36" x 1" aluminum flat (to be referenced as flat "B")
3. one 14" x 36" sheet of aluminum flashing
4. metal cutting shears
5. a yardstick or tape measure
6. three 6-32 x 3/4 machine screws (the long screws)
7. two 6-32 x 3/8 machine screws (the short screws)
8. five 6-32 machine screw nuts
9. one drill with a 1/8" bit
10. one fine point felt tip marker
11. two clamps
12. a pair of pliers
13. a hacksaw
14. Parabolic Template, printed as a poster (3 x 3 = 9 sheets), carefully aligned and taped

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