Home-Brew Antennae: Difference between revisions

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==Turn an Omni into a sector==
==Omnidirectional Antennae==
It is possible to make a homebrew omnidirectional antenna, as shown in the guides listed on [[Links#Antennae]].


The designs shown for a reflector can be applied to a standard omni and will turn the omni into a sectoral antenna.
==Directional Antennae==
===Cantenna===
The instructions shown the websites listed on [[Links#Antennae]] were used to build some cantennae as shown in the pictures:


Taken from: [http://www.freeantennas.com/ Freeantennas.com]
[[Image:P9170496.jpg|thumb|left]]
[[Image:Template.jpg|thumb]]
[[Image:Cantenna.jpg|thumb|left]]
[[Image:Wet-11.jpg|thumb]]
[[Image:Cantenna2.jpg|thumb|left]]


==Cantenna==
[http://www.extremetech.com/article2/0,1558,1643400,00.asp Extremetech guide on building a cantenna]
[[Image:Simulation.jpg|thumb]]
[[Image:P9170496.jpg|thumb]]
[[Image:Cantenna.jpg|thumb]]
[[Image:Cantenna2.jpg|thumb]]


[[Image:Circular waveguide optimise.xls|Spreadsheet for optimising cantenna]]
 
 
 
 
 
 
 
 
 
 
 
 
 
 
'''Left to right,Cantenna on Tripod, Conical Feed element and Cantenna with bicycle spoke element'''
 
This [[Image:Circular waveguide optimise.xls|Spreadsheet]] can be used to optimise the variables when building a cantenna.
 
===Sectoral Antenna===
A sectoral antenna provides the best of both worlds in terms of gain as well as beam-width and can be applied to many situations in mesh networking.
 
====Turn an Omni into a Sector====
 
The reflector designs shown, found at [http://www.freeantennas.com/ Freeantennas.com] can be applied to a standard omni and will turn the omni into a sectoral antenna.
 
[[Image:Template.jpg|thumb|left]]
 
[[Image:Wet-11.jpg|thumb|left]]
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Metal sheeting can be used for the reflector, however, the ideal would be some sort of mesh metal, with holes smaller than 1/4 wavelength (<3cm), so that the antenna is not affected by wind as much.


==Simulation==
==Simulation==
[http://www.si-list.org/swindex2.html NEC tools]
[http://www.nec2.org/ NEC 2] was used to generate the simulated field pattern for a cantenna with the dimensions used in our first test cantenna.


[http://www.nec2.org/ NEC 2]
[[Image:Simulation.jpg]]

Latest revision as of 10:11, 30 May 2006

Omnidirectional Antennae

It is possible to make a homebrew omnidirectional antenna, as shown in the guides listed on Links#Antennae.

Directional Antennae

Cantenna

The instructions shown the websites listed on Links#Antennae were used to build some cantennae as shown in the pictures:









Left to right,Cantenna on Tripod, Conical Feed element and Cantenna with bicycle spoke element

This File:Circular waveguide optimise.xls can be used to optimise the variables when building a cantenna.

Sectoral Antenna

A sectoral antenna provides the best of both worlds in terms of gain as well as beam-width and can be applied to many situations in mesh networking.

Turn an Omni into a Sector

The reflector designs shown, found at Freeantennas.com can be applied to a standard omni and will turn the omni into a sectoral antenna.













Metal sheeting can be used for the reflector, however, the ideal would be some sort of mesh metal, with holes smaller than 1/4 wavelength (<3cm), so that the antenna is not affected by wind as much.

Simulation

NEC 2 was used to generate the simulated field pattern for a cantenna with the dimensions used in our first test cantenna.